Another Internet Canard: ƒ/1.4 Lenses

Oh, dear. I'm about to offend someone again. Someone, somewhere has said something similar to what I'm about to quote, and that person will think I'm directing my disapprobation smack-dab at them, personally, and they will take great umbrage at my remarks and send me an outraged email announcing their intention never ever to visit TOP again. Thus will I eventually alienate the entire world, and be left here amidst the blowing tumbleweeds, talking to myself.

But a quest is a quest and I must do what I must do, and do it I hereby do. For a fake truism has continued to gain circulation courtesy of the internet, one I have raised my lance against before.

It's that "the only reason to buy an ƒ/1.4 lens is to shoot it at ƒ/1.4 as much as possible" or words to that effect.

Of course, that's an opinion, and everyone's got one, and I don't mean to be impolite to those whose opinions differ from mine, but here's mine: that is so wrong. Wrong, erroneous, fallacious, and false. (Opinions: got 'em here, too.)

You can shoot any lens any way you want to. To me, the reasons to shoot an ƒ/1.4 lens might be:

1. It might* make the [D]SLR viewfinder image brighter and the plane of best focus easier to see in said viewfinder. Depending on the viewfinder.
2. The fast stop is available for those rare occasions when you really need it.
3. The "first good stop" is sometimes a wider aperture on a fast lens (for instance, an ƒ/1.4 lens might be better two stops down than an ƒ/2.8 lens is wide open).
4. ƒ/1.4 lenses tend to be more elaborate and expensive to produce, hence a greater number of professionals are among the customer base for them, hence the lenses are better-built and have higher QC than amateur lenses. No judgment rendered here re carts vs. horses, chickens vs. eggs.
5. Some combination of the above.

All fast camera lenses are worse wide open than they are stopped down. All. As in, every one. Unless you've discovered a diffraction-limited fast camera lens that has somehow escaped the notice of optical science.

Here's another factoid from the Walrus: with most fast lenses (although maybe not literally all), bokeh improves on stopping down, too. You might not get as much of it, but it tends to be qualitatively better.

Here's how I usually shoot with a fast lens: I find out where the first good stop is and seldom shoot wider than that. The exception being: when I need or want to.

I'm not saying you shouldn't shoot wide open any time you want to, either. You can make all your pictures standing on your head if it's what you like to do—fine with me. It's the implicit prescriptiveness I object to—the idea that just because someone has a fast lens, it's a good idea to use it wide open all the time.

I would certainly never do anything like wander around shooting everything at ƒ/1.4 regardless of the light and the subject just because the lens I own opens to that aperture. That's [opinion deleted for the sake of politeness to those whose opinion differs from mine].

Mike, fighting the tide 24/7 with lance, steed, and trusty sidekick

ADDENDUM: This whole post could probably have been written much more succinctly, as follows: "What's wrong with buying an ƒ/1.4 lens in order to shoot wide open occasionally?"

*Emendation added after much disputation.

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Original contents copyright 2011 by Michael C. Johnston and/or the bylined author. All Rights Reserved.

Featured Comment by Nikhil Ramkarran: "People who need to be right will no doubt be offended. I'm not. I shoot my fast fifty at ƒ/1.4 because I love the way it does everything badly; its 'badness' is endearing (for the same reason people love their Dianas I guess). But I would never argue that wide open is optimal, although it works for me. An example (might not be great, but I love it):

Mike replies: Ah, there's the right spirit.

Comments

[Bryce Lee]

Aperture size: sounds to me to be an open and shut case.
Also appears to be in part a marketing gimmick.
In the era of film the larger the aperture the better; in the madness of digital simply increase the ISO.
When you get right down to it, is there any real difference?

[Michael]

Are you sure you didn't mean 'rusty sidekick'?

What you say is something I stumbled across early on: if you do manual focus frequently, an f/1.4 lens does the business. The linked point there is that sharpness usually suffers wide open, so even that high quality f/1.4 lens does better taking the actual photo at f/5.6. Taking the two together -- the clarity of focus at f1.4 and the sharpness at f/5.6 -- you're making the most of your probably pretty substantial investment.

[Vincent_ie]

I love my Nikkor AI 55mm f/1.2 but hardly use it at 1.2. Mostly around f/2-f/3.5 because it has the best compromise on sharpness, bokeh and FoV.

[Lou]

I couldn't agree more. I have the 1.3/35mm from Sony, which is a wonderful lens on the full frame body. Yet this lens is getting some harsh reviewing because it ain't razor-sharp wide open, but consider this : at f/1.4 the depth of field is about 1 inch only if you focus at 2ft. This is very difficult to handle or even to judge in the viewfinder.
At 85mm this is even worse.

[Christian Kurmann]

I'd like to hear from the sidekick. What's his take on this?

[Gustaf Erikson]

I agree 100%. In my arrogant opinion, people who wander around shooting wide open in daylight are ... deluded.

[Jacques Pochoy]

Ah... Spot on!
I've even seen people using a density filter to shoot in stark daylight with a f/1.0, for DoF's sake..!
I must be some sort of dinosaur getting f/1.8 lenses to shoot mostly between f/2.8 to f/5.6 (and some days I even reach f/8)!
We live in a blurred world !

[Arnaud]

6. It's more expensive and makes you feel good among photographers;
7. It's bigger and makes you feel good among the crowd (may only apply to men)

I myself am struggling to resist the urge to replace my almost new Zeiss ZE 35mm f/2, by the bigger, dearer and newer Zeiss ZE 35mm f/1.4 (even though I know very well that it will not improve my photography a single bit and that my money would be better spent somewhere else).

[MM]

"I would certainly never do anything like wander around shooting everything at ƒ/1.4 regardless of the light and the subject just because the lens I own opens to that aperture."

I couldn't agree more. I've seen the websites of street photographers who list under each and every photo the large aperture at which the photo was taken (usually 1.2 or 1.4), apparently because viewers are supposed to be impressed by the photographer's fast focusing skills.

But it's easy to isolate subjects and steer the viewer's eye if you only give him one thing he can make out. To me the most impressive street photography isn't shot at f/1.4 or f/2; it's finding order amidst the chaos one finds on the street when shooting at, say, f8 or at least 5.6 (cf. most of the 20th-century masters of the genre). It's worth showing the many layers of street life, not just one layer of it, in part because viewers are much more likely to linger over and return to images that have more than one thing they can make out (cf. Shorpy.com).

Let's be honest: a large part of this "1.4 fad" is due to the wish to separate one's large-sensor photographs from the small-sensor-P&S crowd's "snaps" in which everything is in focus. And part of it doubtless is (with apologies to Mr. Johnston, who imported the appreciation of the phenomenon) obsession with getting as much bokeh as possible, regardless of its quality. But we photographers can't let our defocusing competitiveness let us lose sight of the viewer's interests: that "creamy" background often contains things of interest too. Not always interesting enough to need total focus, but worth being at least discernible.

I remember one of the wedding-forum moderators at photo.net commenting recently on this trend; she said something like, "The bokeh-obsessed photographers are bragging to each other about how little of the background can be made out as the bride and groom come up the aisle [thanks to the impressively large aperture used], while the family who sees the photos wishes they could make out the venue and the faces in the background."

[Marco]

Many SLR focusing screens are unfortunately "optimised" for slower (f:2.8) lenses. The effect of this is that your point 1 is not true: there is no visible difference between looking at the viewfinder with an f:1.4 lens wide open, or stopped down to 2.8 (d.o.f. preview button). You can try it. I can see (that means, I cannot see this) on my Nikon FM2n, for instance.

[Steve Jacob]

Mike, where do I sign up? It's about time someone spelled it out.

Could we add to the campaign people who think that a face with only one pupil in focus and the other features blurred into an amorphous mass is a portrait. It's not, it's a picture of an eye.

Steve

[Walt]

Go on to bed Mike. We'll make sure those poor misled people on the internets know that they are wrong. Me, I've still got a few edits to go on my 100 windmills in 100 days with a Canon 50mm f1.2. Just can't get those horizons level for some reason.....

[Jim McDermott]

Mike. some good points, but others missed. Clearly you haven't appreciated the tumescence of, say, the new Samyang 35mm f1.4 compared to the frankly pee-pee qualities of the average f2.8 equivalent.

And, perched on top of one's pile of Barry White albums, it removes any ambiguity about the reason you issued that dinner invitation.

[Edi Weitz]

Well said. From my observation, the "wide open" cult is something that's particularly widespread among Leica aficionados. A telling example is a Danish pro (offering paid workshops) who under "best practice" has to say: "I don't use the aperture at all. [...] My aperture is always set to fully open." Quoted from http://www.overgaard.dk/leica-M9-digital-rangefinder-camera-page-12.html

I'm using Leicas myself, but I never understood this attitude. And seemingly all the famous Leica photographers from the last century didn't either. At least I can't recall any "wide open" shots from Cartier-Bresson, Frank, Klein, Winogrand, Eggleston, Erwitt, Koudelka, and so on.

[Gordon Lewis]

Here's a reason you might NOT want to shoot with an f/1.4 lens: It will be a lot bigger, heavier, and more expensive than its f/1.8 or f/2 alternative--and there is almost always an f/1.8 or f/2 alternative. The best aperture will still be around f/4, so why pay more for f/1.4 unless you really need it?

[Kyle]

I generally only shoot wide-open when it's night or I'm inside or I'm taking a portrait. Though there are times that I'm shooting in the street that I enjoy stopping down to at least f/2 because I like how my 50/1.4 renders the slightly out-of-focus areas. Mostly, my street photography is shot at around f/5.6.

I agree with MM. Some of the most interesting street photos are the ones where everything is in focus, it shows that the photographer was able to find that order in the chaos.

However, some of that might also have been technical limitations of the day. Some rangefinders (and others) couldn't shoot faster 1/1000th, and ISO 400 film was common. At that point you don't have any choice but to stop down a few stops or you'll ruin your exposure.

[Geoff Wittig]

Very long lenses are the exception to the rule, in that they are frequently sharpest wide open. For example, Canon's 500 mm f/4 doesn't get any better as you stop down, and actually loses sharpness from f/8 onward. This dovetails nicely with the need for the fastest possible shutter speed with these lenses. The only reason not to shoot wide open is to eke out a little more depth of field.

Of course, that's also why these things cost as much as a decent used car and weigh nearly 10 lbs.

[David Dyer-Bennet]

It was widely rumored (in the late 1970s) that the 90mm Summicron was best at f/2; but I never bothered to test it, and it probably wasn't true. It was good enough at f/2 for candid portraits in my opinion, which was what I used it for mostly. There was no reason to pass up an opportunity because the light required f/2.

With autofocus, what I see in the viewfinder is much less important than it used to be. But the AF mechanism ALSO benefits from shallow DOF and more light, so that's still relevant.

I never really did get trained to try to avoid the wider apertures. For my purposes, except when more DoF is required, I haven't found them noticeably inferior (mostly for candid individual and very small group portraits).

I gave up my great f/1.2 lens (Nikkor 58mm NOCT) as pretty much an even trade for the D700 body. That was one heck of a deal for me; I gained a LOT more than 1 stop of ISO, plus I wasn't doing too well with manual focus at f/1.2 on a DX body.

I don't currently own a real f/1.4 lens (I own a 75mm f/1.4 TV lens with adapter for the Olympus E-PL2, but it's not very satisfactory so far; more testing needed).

If somebody offered me the Nikkor f/1.4 boxed set (35, 50, and 85), I wouldn't turn it down!

[John H. Maw]

The piece is well phrased, but some of the comments seem to miss the point. It's good to have the option of wider and smaller apertures, as it is to have any other options that might help us to express how we want to see and reproduce a subject. Laying down rules is not responding to the subject or your reaction to it.

Stay flexible and spontaneous. Rules are for those who cannot see.

[Mike Johnston]

"However, some of that might also have been technical limitations of the day. Some rangefinders (and others) couldn't shoot faster 1/1000th, and ISO 400 film was common. At that point you don't have any choice but to stop down a few stops or you'll ruin your exposure."

Just so there's no mistake, this is *definitely* a modern (i.e., last decade) attitude. In "the day" you're talking about, the concern was the opposite: the desire was for more depth of field, not less. Just keeping the historical record straight.

Mike

[Mike Johnston]

MM,
I suspect another aspect of the popularity of wide apertures is that lenses have become "too" perfect: analytical, hyper-detailed, lacking character. More blur is a way of introducing some artistic ambiguity and character back into pictures that otherwise might have a forensic quality, an antiseptic lack of ambiguity.

Maybe? Just a thot.

Mike

[Mike Johnston]

"Very long lenses are the exception to the rule"

Okay...I know almost nothing about really long lenses. The longest lens I've shot with in the last ten years is 110mm-e, so I'm not familiar with longer ones. I think the longest lens I *ever* shot with was a 400mm (maybe it was a 300mm--I can't remember), and that was only once, for one day in the early '90s.

Mike

[di-sign]

+1 Marco
I have not seen any current dslr that uses an opening brighter than f2. I think its really f2.8 and after that makes difference.
I am quite sure You made the same point on this same site sometime ago.

Otherwise I think You are right, just not this first point.

[Jim Bullard]

Bryce said,

"Aperture size: sounds to me to be an open and shut case."

Groan. That is sooo BAD. I love it. :-)

[di-sign]

What I meant was that Michael made the same point on this site, not Marco. Sorry for the bad choice of wording.

[Max]

One reason to shoot wide open? Because with manual lenses you get working Av on digital bodies!!
But no, I don't shoot wide open much either. In fact, I want to try a Tessar lens with the K5. The few air to glass surfaces is an advantage set in stone. And I guess a good modern Tessar at f/8 should be almost apochromatic. Fast lenses do have aberration issues, even at moderate apertures. And I came to notice I hate CAs. Nobody would take a 50/3.5 lens seriously these days, but with modern coatings the performance should be stellar color-wise, and stopping down should take care of sharpness too.

[Mike Johnston]

"I have not seen any current dslr that uses an opening brighter than f2."

I'm not sure what this means. DSLRs don't have aperture openings...only lenses do, and clearly some lenses have apertures wider than f/2.

Mike

[MarcW]

I have the Canon 50mm f1.8 and the Canon 50mm f1.4. Those wishing to verify that the points the poster makes about the difference in quality, materials and comparative image quality at the same aperture settings are valid in at least this case need only compare them. I literally could not believe how much better it is. Of course it costs three times as much, but you often get what you pay for. (I can only imagine the step up to the f1.2.)

That being said I've made some very nice images with the Nifty Fifty and continue to recommend it as a good, inexpensive and flexible choice for a new photographer's first prime lens. It's lighter, smaller, and if something happens to it, well, big deal.

[Mike Johnston]

Admission: I cheated a little, and changed the post a bit. (I added the second to last paragraph.) In objecting to people saying you *must* shoot wide open all the time, I certainly don't mean to make the opposite error and say you should never shoot wide open. You should do whatever you want to do or feel is needed, of course.

Mike

[Max]

Since we're talking lenses here, I will add something about primes. I don't like zooms. And I'm sure there are excelent zooms out there today. It's just that when I pick up a 50/1.4, close it down to 4 and shoot, the whole thing makes sense in my mind, I know what to expect. When I add variable focal length... there are just to many variables in the equation, I don't know what to expect any more.

[Nicholas Condon]

Gordon Lewis beat me to the point I was going to make, more or less. For me, I wouldn't bother buying a lens that I wouldn't be willing to use wide open, under the right circumstances. If f/1.4 is so bad that I'd rather bump the ISO up a stop and shoot at f/2 instead, I'm probably gonna pass up the f/1.4 entirely and buy an f/2.

[ILTim]

Yup. I had a Sony 50mm f/1.4 that sucked at 1.4, and kinda sucked at 1.7, but was AWESOME at f/2. The bokeh turned nice, there was an explosion of sharpness, etc etc. At f/2 it rocked way more than the f/1.7 lenses did at f/2. Who knows what the image quality difference was at 5.6, maybe nothing.

Easier focusing due to brightness and dof, very welcome features.

Option to use a soft-focus f/1.4 lens by thumbing the aperture wheel, welcome feature.

A good 1.4 lens? Nope. Not at all.

Now the micro four thirds Panasonic 20/1.7 rocks it wide open, THAT lens can be bought to shoot 1.7 or f/2 all day every day. But f/4 does still have its charms, and can, and should be used when its appropriate. So anyway, even if your brain dead and you shoot every image at f/4, the faster lenses should generally turn in better results and be more useable than a f/2.8 or f/4 lens.

And I thought everyone knew that.

[Dennis Allshouse]

"Gypsy Davy, with a blowtorch, he burns down their camps.
With his faithful slave Pedro behind him, he tramps."

Bob Dylan, "Tombstone Blues"

[Andy K]

I'd be willing to take any old yucky Pentax-A 50mm f/1.4 or f/1.2 lenses you want to unburden yourself of.

[KeithB]

Mike as far as the DSLR aperture and view finder goes, here is [name deleted --Ed.] l discussing the issue: [link deleted --Ed.]

Viewfinders for zoom-expected DSLR's are optimised for f/2.8 and slower lenses and don't get brighter with wider apertures.

You should be able to perform your own experiment to try this out.

[psu]

Other reasons to shoot a fast prime:

1. Smaller than a fast zoom.

2. Often smaller than a slow zoom.

3. With auto-iso and a D700 you can shoot away almost anywhere and just not think about it. Unless you want to think about it.

4. The lens is so small!

I continue to use my Nikon 35/2 and 50/1.4 even though they are apparently marginal wide open compared to more modern designs. I never noticed what the problems were before, so why worry now. I have bigger problems making good pictures without obsessing over lens performance.

[Dennis]

Another reason to buy an f/1.4 lens: there's no f/1.8 option available.

I have a Minolta 85/1.4 (bought used, didn't cost much more than a new Canon 85/1.8 so worked out ok). I rarely shoot it wider than f/2 (I frequently shoot it at f/2 ... I prefer my CZ16-80 zoom that's smaller, lighter and faster-focusing if I'm not shooting for shallow DOF or low light). I would have happily bought a smaller, lighter, cheaper f/1.8 lens if one were available. (Sony's new 85/2.8 checks all those boxes, but I don't think I want to give up f/2).

[Frank Barbas]

>>"I have not seen any current dslr that uses an opening brighter than f2."

I'm not sure what this means. DSLRs don't have aperture openings...only lenses do, and clearly some lenses have apertures wider than f/2.<<

I think the poster meant that the view finder of a modern DSLR, only shows DOF down to f2.8, any faster/wider, viewfinder does not show less depth of field. Very annoying to judge your depth of field or manual focus lens faster then f2.8. Nor does the viewfinder get brighter with lenses faster then f2.8.

[Gerard]

All of my Zuiko Digital lenses perform perfectly fine wide open...in fact, my ZD35/3.5 macro is sharper wide open than it is stopped down. I was amazed when I got a Sigma lens that I actually had to stop down for better performance!!!

[Peter Hovmand]

I agree, just bought the Nikkor AI-S 35mm 1.4, and it is just beautiful! So happy didn't go for the 2.0 :)

[Doug C]

Mike,
"I have not seen any current dslr that uses an opening brighter than f2."

I'm not sure what this means. DSLRs don't have aperture openings...only lenses do, and clearly some lenses have apertures wider than f/2.

Mike"

I think Marco and di-sign mean that they have not seen a modern SLR whose finder is brighter and easier to focus at lens openings larger than f2.8. Only my Nikon FE is brighter with the f 1.4.
But I still use my 1972 50mm f1.4 Nikkor S on my D700 most of the time despite the fact that I own "better" 50s. I can't really explain why other than I like the feel and handling of it.

[David Dyer-Bennet]

"I generally only shoot wide-open when it's night or I'm inside or I'm taking a portrait."

Yes, exactly. And those conditions account for 90+% of my photography. For me, shooting outside is an exceptional situation. And my equipment isn't ideally suited for it!

In 1970, none of the mainstream cameras had shutter speeds over 1/1000 that I can remember. And medium-format gear with in-lens shutters (leaf shutters) didn't go above 1/500. And cheaper SLRs like the Mamiya 500 were limited to 1/500 even on their focal-plane shutters. (The "Speed" Graphic, somewhat before 1970, had that name because it had a focal-plane shutter in addition to the leaf shutter in the lens; using the focal plane shutter you could actually get 1/1000 sec. on 4x5 sheet film. That fairly slow-moving shutter on the big sheet of film gave rise to the tilted oval wheel convention for fast-moving cars.) (By "somewhat before 1970" I appear to mean "1912").

[GH]

Of course, the problem with most fast lens designs is that they don't compete as well across the frame as their slower counterparts do at mid apertures, so you may be giving up performance at f5.6 for the option of f1.4. It's all about trade offs.

Also, because digital sensors don't receive angled light rays as well as film, the amount of light being read by the sensor isn't linear as the apertures get wider. For example, you may have a 1 EV difference between f2.8 and f4 on a particular lens, but the difference between f1.4 and f2 on the same lens may only be .5EV, so one must really balance the positives/negatives of using fast glass.

I recently decided to try the "slow" Zeiss ZM 35/2.8, and it happens to be sharper at f2.8 than any of its faster counterpoints, and it is essentially free of aberration at any aperture. It's bokeh is very good, especially for a Zeiss. :) After using f1.4 lenses for years, I took a chance with this "slow" prime, and it is turning out to be one of my favorite lenses of all time. Go figure!

[Darren Melrose]

Mike, you have covered the best reasons for owning f/1.4 (or 1.2) lenses and I agree with all of them.

You pretty much hinted at it, but I will be a little more blunt. There is a good reason why some folks should not be allowed to really fast lenses; they will only shoot at that aperture. I have grown so tired of looking at galleries with ultra shallow DOF and far too many photographers rely on that one trick way, way too often.

Actually, I feel much the same way about photographers whose every photo seems to have been taken at 14mm, after a while, every photo looks the same to me. What is worse in my opinion is that photographers who are always shooting at the extremes, be it wide angle or wide aperture, really aren't showing what they can do with a camera so much as they are showing what their camera can do. It becomes an equipment showcase rather than a photographers showcase and that is a little sad to me.

[Paul Glover]

Wide open is fine for "available dark" shooting, if you really have severe flash phobia. Personally I'd rather make my own light with some bounced flash and stop my fast 50 down to f/4 +/- a stop or so. It usually looks better and I tend not to miss focus so often!

I admit I do carry a 3-stop ND in the event that I might want to do the shallow DOF thing in outdoor light, you know, an "artistic decision" based on the subject and what I want to make of said subject. I've shot maybe 3 or 4 frames with it out of a couple of hundred without. Even then none were wide-open if I recall correctly.

[David Aspinall]

Even though I am a long term M user I could never understand the following for 1.4 or faster on an M becuse you only see what you are getting on an SLR like the A900.

David

[latent_image]

"I suspect another aspect of the popularity of wide apertures is that lenses have become "too" perfect: analytical, hyper-detailed, lacking character."

I don't think it's just lenses. I also think it can often be in the character of digital imaging itself: those areas of perfect smoothness and too many, too sharp edges. Going blurry is a way to counter that.

Before readers rise up in protest, let me affirm that digital photography has advanced tremendously in recent years, and the tell-tale signs that simply screamed "digital" have been receding at a fast rate thanks to better technology and better skills.

Neverthless, if one makes a large darkroom print and a large digital print from respective cameras set up on adjacent tripods, the darkroom print can be instructive with respect to fine texture and as to where sharpness and unsharpness ought to fall in an appropriate way (thereby enhancing a sense of three-dimensionality).

Our eyes give us the world through lenses. Sometimes with digital, I think we stray from lenticular logic and up with images that feel artificial and flat. As Mike said, shooting wide open can be a "way of introducing some artistic ambiguity and character." Not always the best way, but a way.

[Semilog]

"All fast camera lenses are worse wide open than they are stopped down. All. As in, every one. Unless you've discovered a diffraction-limited fast camera lens that has somehow escaped the notice of optical science."

The Olympus Zuiko 150mm f/2 comes astonishingly close to that ideal.

[Dennis]

Mike listed reasons to use a fast lens (besides shooting them wide open) and I added that sometimes you buy faster than you need because you can't get the lens you need. Arguing for the prosecution, dxomark is among sites that have observed that camera manufacturers "secretly" increase the brightness of your image (simulated ISO boost) in many cases when you shoot wide apertures (from f/1.2 through f/2.8) because the sensor "sees" less light than the lens transmits, presumably due to the angle of incidence at wide apertures. The net effect is that while f/1.2 still ends up giving you more light than f/1.4 and f/1.4 more than f/2 and so on, the increase in exposure is less than the increase in lens opening. In other words, you don't get what you pay for. Disturbingly, the charts at dxomark show the under-the-covers gain being higher for the highest density sensors. So a Canon 60D user sees less benefit going to an f/1.4 lens than a Canon 20D user, or a Nikon D300 user. The downside of this is that it effectively means you can't shoot wide open at base ISO with an f/2.8-or-faster prime. It would be nice to have an option to turn that off and allow you to compensate with a slightly longer shutter speed (assuming you have that luxury; often you're above base ISO when shooting fast anyway, so it's a moot point). I'm not sure there's much practical value in the knowledge. f/1.4 is still "faster" than f/1.8 after all, and all the other benefits of the faster lens are still there. (IIRC, the jury is still out on the bokeh question - whether the light rays that aren't being seen affect the OOF portion of the image).

Here's a link if anyone is interested:
http://www.dxomark.com/index.php/Our-publications/DxOMark-Insights/F-stop-blues

[richardplondon]

I have not seen any current dslr that uses an opening brighter than f2

If I may suggest an expansion of that: while all the light may travel through the lens, the fastest apertures are not necessarily made full use of in some respects.

First, the sensor surface may be less receptive to light rays with an incident angle too far off normal.

Next, the standard focusing screen of a typical dSLR has a bright prismatic treatment. Through this, we can get only the focus definition and brightness of an "effective" aperture not much wider than f/4, whatever lens is fitted - a tradeoff to counter the darkening seen with slow lenses through plain focus screens.

Also, as I understand it, dSLR autofocus sensors are designed to a lowest common denominator. If the real lens aperture were ever to be smaller than, and thus to vignette, the detector's "virtual aperture" this could affect its operation. In some more expensive models an additional central AF detector is designed for a larger cutoff aperture (say, f/2.8 or so). This extra sensor is not employed unless a fast enough lens is detected; but a faster lens still will not be profited from, in this respect.

[Richard Man]

Shoot with a modern Leica (vs. the old Barnack). Whether you are chewing film with an M7 or MP, or sucking pixels with the M8 or M9, it does not make sense to buy slower lens.

A Leica with a 3 'lux kit is still much smaller than a dSLR with one zoom. And this is where you see Leica separating from the pack of Canikons.

Of course this does presume that you started earlier when the (used) lens prices were merely stratospheric rather than waaaaaay out there.

[Sean]

One of the great things about lightroom is that you can check a years worth of metadata in a couple of clicks. I've got 2007 up right now

Of the 51 shots I took/kept with my 35mm F/1.4 wide open that year. 39 of them are under 1/60th sec, 32 of those came with an ISO of 3200.

I shoot a lot in bars and when needs must it's handy to have it when you need it (and had a few). But I've 400 shots from that year that are F/2 and beyond. I've never bought a lens for its bokeh, which may seem odd as people are crazy about it

[Mike Johnston]

"the view finder of a modern DSLR, only shows DOF down to f2.8, any faster/wider, viewfinder does not show less depth of field....Nor does the viewfinder get brighter with lenses faster then f2.8."
-----------------------
"Viewfinders for zoom-expected DSLR's are optimised for f/2.8 and slower lenses and don't get brighter with wider apertures...You should be able to perform your own experiment to try this out."

Stuff and nonsense! How would the viewfinders do that, by magic?

The only way would be if open-aperture metering was "limited" to the f/2.8 stop, like a rev-limiter on an engine. And for all I know, maybe some cameras do this.

But in the spirit of empiricism, I actually DID perform my own experiments...I happen to have two identical camera bodies here, and two lenses of very close to the same focal length but of more than a stop difference in maximum aperture (31mm f/1.8 and 35mm f/2.8).

And, of course, the faster lens shows a brighter viewfinder image and less d.o.f. in a careful comparison. (Although I felt a little sheepish actually running the experiment, like when your friend is looking up and says, "how about that, someone wrote 'gullible' on the ceiling," and you look up at the ceiling.)

I do NOT want to pick a fight with your expert, which is why I elided his name, but that's just another eye-rolling internet myth as far as I'm concerned. Of course, maybe he's using a Whapoflex and his camera works differently than mine--I can't speak to that.

Bottom line, don't believe everything you read on the internet!

Mike

[Sean]

"The longest lens I've shot with in the last ten years is 110mm"

Looking again at metadata in lightroom I've just noticed that I use my only zoom (70-200mm F/4.0 IS) as a 70mm F/5.6 prime

[Mike Johnston]

GH,
Yes, I've been hearing through *my* sources that that lens is a sleeper. And, really, there's not as much need for a fast lens on a rangefinder.

When we draw comparisons between "fast" and "slow" lenses, we have to remember that we're talking generalities, sort of like predicting the outcome of a football (soccer) or (American) football game based on records, past meetings, and player matchups...just because one lens "should" win doesn't always mean it does. All else being equal, a slow lens should be optimized better than a fast one...it's just that "all else being equal" is all in the details, and seldom is.

Mike

[Mike Johnston]

"The Olympus Zuiko 150mm f/2 comes astonishingly close to that ideal."

Yes, I think I'm on thin ice with my absolutist statement given how little I know of extreme teles. I might have to dine on a little crow where that's concerned.

It's not like that hasn't happened before...in fact I'm rather beginning to like the gamey taste of crow. Haven't gotten used to the taste of my foot in my mouth, however.

Mike

[Mike Johnston]

"The best aperture will still be around f/4, so why pay more for f/1.4 unless you really need it?"

Well, see reason #2 in the post...because you might need it sometimes.

Mike

[Dave Stewart]

Did I miss this one somewhere above? - Stop down to reduce vignetting.

[Jack]

"And, of course, the faster lens shows a brighter viewfinder image and less d.o.f. in a careful comparison. (Although I felt a little sheepish actually running the experiment, like when your friend is looking up and says, "how about that, someone wrote 'gullible' on the ceiling," and you look up at the ceiling.)"

Doesn't sound like you did the right experiment. Use one lens. Stop down to somewhere around 2.8. Look through the viewfinder. Now while still looking through the viewfinder with DOF preview enabled continue to open the lens. At what point do you stop seeing a difference in image brightness and DOF? I know my Nikon D200 stops showing a difference before the 55mm f/1.2 is wide open. Try it again.

[Tobias Key]

Mike

Regarding focussing screens that show an F4 aperture when set to 1.4. I switched my 5d mkII mark to Canon's optional Eg-s screen, and as there is a noticeable 'thinning' of the depth of field from the standard screen. Not only that, as a test I stopped down my 1.4 lens with the standard screen in, there seemed to be no perceptible change in brightness or depth of field down to F4. Whether the DOF is just more noticeable or whether it's a genuine effect I don't know, like you I think it seems to break all the laws of physics. Nevertheless the effect is certainly observable to me.

[Njwv.wordpress.com]

There are also those of us who have multiple 50mm lenses. After all, the f/1.8 or f/2 versions are typically very cheap. I have an f/1.4 which I only use at f/1.4 since I usually don't need that extra speed and would rather carry the lighter-weight f/2 lens.

[Craig Arnold]

Well, surely you choose the best lens for how you like to shoot.

Ferinstance - on FF sensors or film I like to shoot a 50mm at f2 or f2.8 for portraits.

On my Canons I have owned the 50 f1.8, f1.4 (twice), f1.2.

The 1.8 is sharp but nasty and the background blur is truly horrid to behold. The 1.2 draws beautifully, but isn't as sharp as either of the other two at f4-f8, and I could never get my "in-focus" rate to anything more than around 50%. The 1.4 on the other hand is very sharp, has no weird focus issues, draws fairly nicely, is not expensive and not too heavy. It works just great at f2-f11.

My Zeiss Ikon has two easy options at 50mm: the f2 Planar and f1.4 Sonnar. The Planar is sharper everywhere than the Sonnar, I like its drawing though both are nice, and it has no focus shift. So I use the slower lens once again.

So I think I disagree with you slightly.

But I am 100% in agreement that a fast lens need not be shot wide open to justify the purchase. That's just craziness, and leads to people shooting their new X100 (23mm lens!!) at f2 for head shots trying to get blurred backgrounds and then bemoaning the results. Ridiculous.

[Will Frostmill]

I'll note from personal experience that the Olympus E-520 doesn't meter correctly with a Nikon E-series 50mm f/1.8 wide open compared to f/2 or f/2.8. It overexposes by almost a full stop when I examine the histogram. My theory is that wide open I'm getting internal reflections that are helping to saturate the sensor in a way the exposure algorithm doesn't expect, and that the extra exposure is mostly internal glare. (It's a really cheap, internally shiny adapter.)

I have speculated that the smaller mirror misses light that would otherwise be accounted for by the exposure meter, when the angle of light entering the camera is too wide.

I regard the Dx0 findings with interest and skepticism.

Will

[GH]

Yeah, Mike, the C-Biogon 35 is a killer...but I use it on a NEX-5 of all things! It is so good on a crop camera that I don't even worry about which aperture to use as far as IQ goes, just light and DOF.

Outside of some fast Leica ASPHs, I would say it's pretty common for slower lenses to perform better at mid apertures than their faster counterparts, and I do think the trade offs of size and various aberrations of fast lenses are often underestimated. That being said, I do own many fast lenses, and I usually do stop them down at least one stop, unless the light forces me otherwise.

Ultimately, I agree with your point overall. For me, with any lens, wide open is a last resort (except with the C-Biogon.)

[Siegfried]

7. It's bigger and makes you feel good among the crowd (may only apply to men) (C) Arnaud

Well, if I got it right then women must be happy with two F1.4 lenses?

Zig

P.S.
Some like P. Anderson may need to go further: e.g. to F0.95

[Mike Johnston]

"Doesn't sound like you did the right experiment. Use one lens."

How does using one lens tell you anything about the difference between using a slow lens and a fast lens? That's what we were talking about. The best way to test that is to test that, not to test some other thing.

In any case, no more tests for me. You're free to do your own, and, of course, to proceed from your own results rather than mine.

Mike

[Bahi]

> But in the spirit of empiricism, I actually DID perform my own experiments...

To make sure you're testing for the effect of aperture only and not the effect of lens design (number of elements and other things changing the effective t stop), use the same lens, focussed on the same item, and then the depth-of-field preview button to compare viewfinder brightness wide open with brightness at your chosen aperture. If you use an f/1.8 lens on a DSLR, do you see a difference in brightness if your chosen aperture is f/2.5 with the DOF preview held down? I've done this test on a stack of APS-C DSLRs over the years and have never seen a difference till f/2.8, minimum.

Five minutes ago, I tried a 550D (pentamirror, crop sensor) with a 50m f/1.8 and a Nikon D80 (pentaprism, crop sensor) with a 50mm f/1.8 -- no viewfinder darkening with DOF preview till I'm stopping down to beyond f/2.8 (in third stops) on either camera.

I've also just tried an F90s (N90x in the US) film SLR with a 50mm f/1.8 and although it shows no difference in brightness at f/2, the darkening of the viewfinder at f/2.8 is significant. The lens I'm using doesn't allow me to test f/2.2 or f/2.5 but I'd probably see a difference earlier on if I could set third-stop apertures.

As for DOF, I've consistently found very different results (bokeh, etc.) in the shot compared with the viewfinder image wide open. I'm talking about very, very big differences, particularly for close-focus work. I've long since concluded that the crop DSLR viewfinder tells fibs for apertures larger than f/2.8 but I'd love to be proven wrong. (It would only take one DSLR with a a focussing screen that worked differently…)

[Mike Plews]

Unless I'm having one of my senior moments here I think the original Leicaflex had a viewfinder that omitted ground glass in favor of a split image assist in the center of the field.
I believe the rationale was that an aeiral (?)image was brighter and the split image thingie was more rangefindery.
As best as I can tell all they succeeded in doing was optimizing the viewfinder for no lens ever made.

[Ed]

I like my old Nikon 1.4 50mm because:

A: it was deadcheap (100 dollars second hand)

B: on my GF1 it turns itself into a 100mm 1.4 (now try to get that in full frame)

C: it has a great shalow depth of field (even using a smaller sensor)

D: I like the boukeh (<- subjective so don't bother to argue)

http://www.xs4all.nl/~stomoxys/content/content/Dreamscape_3_large.html

So nope, not bought for 1.4 but it does tricks my regular Pana and Oly lenses can't do verry well. And that at a fraction of the cost of a Voigtländer (if I win the jackpot........if).

Greetings, Ed

[Roger]

I love the comment about the "badness" ahh the badness.....I also concur that the Canon Nifty 50 while great value (full of badness) only really starts to get good at f5.6 so the bragging rights can quickly fall short for low light hunters and the bokeh purists.

The article does remind me of my Pentax FA50 f1.4 which I bought for such quests for bokeh and low light situations. Strangely I found myself always having to stop down until it became clear my DA35 f 2.8 could simply produce a more contrasty and sharp image at the same aperture starting at f2.8. Ironic that even the new plastic fantastic DA35f2.4 AL el cheap o wonder by Pentax would also have been better for me.
However many still bemoan the exclusion of f1.8 on this lens. The question is did Pentax simply feel including soft performance is not worth the cost to build just for the bragging right?

In the confused world of online forums many are obsessed with "faster means better" regardless of class or price category.
If this is you good hunting but for me I have really come to appreciate stopping down and using more than bokeh as a crutch effect to isolate or create interest.
Thanks for the comments everyone!
Cheers

[Crabby Umbo]

Did someone on here actually say a fast lens shut down, to let's say 5.6, is sharper than a slower lens shut to the same aperture? If so, that would be a miracle for me, 'cause that's never been true in my lifetime, unless lens design has changed so much with digital, I don't even recognize it. Slower lenses were always sharper at smaller apertures. 1.2's and 1.4's were generally made to be specialty lenses when people really needed that in low light, available darkness, so to speak.

People who say: "well, I need that 1.2 because I shoot in bars, or at night, or...", must also mean: "...and I only need one inch in focus...", because it doesn't matter how dark it gets, I still need more than a few inches in focus for what I shoot.

But seriously folks, those of us who shoot for ad agencies or commercial needs generally have to get a certain amount of things in focus for the client to sign the check. The beauty shot of the widget isn't going to happen if 95% of it is out of focus. I've basically never shot wide open at all, anything. Having said that, there are times when you are doing 'art', or need a more 'poetic' look to something, where what we refer to as 'subjective focus' may fill the bill, and nothing meets that need better than a fast lens wide open!

Of course, I only need one lens like that for specialty shots, the rest of the time, and I'm talking to you Nikon, where are my f/2.8 G lenses! For 300 bucks! Bah!

[daragh]

I've thought the same thing for some time. I event went so far as to think that f/1.4 lenses were excessive when it seemed far more practical to make a great f/2 lens instead of catering to the depth-of-field thirsty populace. Then I bought an f/1.4 lens.

Although, I will say that the f/1.4 lens I bought was because some trickster convinced me to buy a Leica with a view to using it for a year or more and it came down to cost. The CV 35/1.4 was a lot cheaper than the ZM 35/2 and any of the Summicrons.

I don't use it at large apertures in daylight. I couldn't if I wanted to: the only film I'm using is Tri-X and I don't have a neutral density filter for it, so I can't get anywhere near f/1.4 until the light levels drop significantly. Althought I'm thankful for having f/1.4 as an option, and it is used out of necessity quite often.

I realised that I don't like the look of 135-style shallow depth-of-field in what is obviously full daylight; it just looks wrong. I much prefer the deep focus look of brightly lit scenes, but the foreshortening depth-of-field as the lighting becomes more intimate. I think that's part of the established visual grammar of photography, and I don't think it should be broken without specific reasons.

[David Bostedo]

Using an Olympus OM 50mm f/1.4 on my E-520, which requires manual aperture selection and thus no DOF preview needed :

1) I can't seem to see a brightness difference between f/1.4 and f/2, and I think I see a very subtle one between f/2 and f/2.8. Beyond f/2.8 the difference between apertures is obvious.

2) My camera also shows the metering anomaly noted above, where f/1.4 always overexposes by at least a stop, whereas smaller apertures the metering if fine.

I've gotta think this has something to do with the angle of light rays at wide apertures, and the angles of the mirror, and penta device (mirror or prism) in the viewfinder. So not magic, no, but suprisingly to me, there seems to be something to this for this particular combo at least.

[David Bostedo]

And while we're at it, here's a very similar discussion from the forums of Nature Photographers Network.

[ctein]

Dear folks,

I looked at the graphs for the Olympus 150 mm lens and the sharpness stays constant until you get below f/4, which says this is a very well corrected lens, but it doesn't go diffraction limited until it's two stops down.

That's how you tell if a lens is diffraction limited. If the entire field of the lens is getting blurrier as you stop down, that it is. If it's not, then it's not.

Note that this is very different from a lens that performs at the diffraction limit. An unfortunate and unavoidable potential for confusion.

~~~~~~~~

Regarding this business of SLR viewfinders not being good with fast lenses, this demonstrates a profound misunderstanding of the importance of one fact. Namely, the microprisms or split image finders in viewfinder screens are designed with a certain f-ratio in mind. The reason for this is that the larger the aperture they're designed for, the more precise they are–– it's like having a longer baseline on a traditional rangefinder. But if you try to use them with a lens that is stopped down to an aperture smaller than what they're designed for you'll get blackout; half the split image or alternating microprisms will go black. You can readily demonstrate this with a regular lens just by manually stopping down.

So there's a design compromise involved. A “faster” focusing screen gets you more accuracy but there will be a more lenses that you can't focus with at all, even wide open. Hence, it's normal for focusing screens to be designed for f/2.8 or even smaller apertures.

That indeed means that the focusing aid in the screen won't work any better with an f/1.4 lens than an f/2.8 lens.

BUT THAT'S ALL IT MEANS!

The image through the viewfinder will still be brighter with the faster lens, you'll still be able to better judge out-of-focus areas with the faster lens. And if you're using a viewfinder screen that doesn't include a focusing aid, like a pure fresnel or groundglass/matte screen, you will be able to focus better with the faster lens.

Any website or web author you read who claims otherwise does not know what he's talking about.

pax \ Ctein
[ Please excuse any word-salad. MacSpeech in training! ]
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[Dave Elden]

Bahi wrote:
“I've also just tried an F90s (N90x in the US) film SLR with a 50mm f/1.8 and although it shows no difference in brightness at f/2, the darkening of the viewfinder at f/2.8 is significant.”
I just tried the same test with an FM2n & Nikkor 50mm/f1.4: no visible effect on VF brightness or DOF below f2.8. Also the meter wasn’t sensitive to operating the preview lever until stopped down to 2.8. At f2 there was no change in reading when I operated the preview lever – even though I can see the aperture blades moving as expected to reduce the aperture area. As Mike points out this isn’t comparing fast & slow lenses but it still surprised me – especially the meter part. I really thought I understood how an FM2 with a 50mm lens on it worked but now…

[Bryce Lee in Burlington, Ontario Canada, eh?]

""Bryce said,

"Aperture size: sounds to me to be an open and shut case."

Groan. That is sooo BAD. I love it. :-)

Posted by: Jim Bullard | Wednesday, 20 April 2011 at 08:36 AM""

Jim: I have no shame hence the pun!

[Mike Johnston]

I apologize for being so short earlier. I should learn not to play the know-it-all; I'm not comfortable with that role and I'm no good at it.

I've amended the post to account for the various objections.

Mike

[Ken]

-> "Doesn't sound like you did the right experiment. Use one lens. Stop down to somewhere around 2.8. Look through the viewfinder. Now while still looking through the viewfinder with DOF preview enabled continue to open the lens. ... Try it again."

Umm, also be sure to stand on three toes of your left foot, use your right arm bent at the elbow for balance and stick your tongue out when you try it... Sorry, but to me that's about as inane as it gets. I'd rather spend my time shooting or even editing than running meaningless tests on viewfinder brightness measurements. Different strokes for different folks, I guess...

Btw, thanks for the post Mike - your reasons are precisely what I shoulda told my gf when she asked me what I thought of her new Canon 50 1.2! ;)

[Jack]

"The image through the viewfinder will still be brighter with the faster lens, you'll still be able to better judge out-of-focus areas with the faster lens. And if you're using a viewfinder screen that doesn't include a focusing aid, like a pure fresnel or groundglass/matte screen, you will be able to focus better with the faster lens.

Any website or web author you read who claims otherwise does not know what he's talking about.

pax \ Ctein"

I contend that your contention is incorrect for the range between f/2.8 and f/1.2 on a Nikon D200 based on experimental evidence. It is probably incorrect for other cameras as well. It is so easy to check - why not give it a try? Put the camera up to your eye, press the DOF button and change the aperture to something wider than f/2.8. You can prove it in less than a minute.

[hugh crawford]

I somehow accumulated 1nd use 15 50mm lenses. I blame Michael our host and the fact that nice 50s can be pretty cheap, cheaper if you buy them with a camera still attached like peanuts still in their shells. All of them are fast enough for using in the subway, most of them look about the same at f/8 but in the range of f/1.2 to f/5.6 they are like low watt tube guitar amps turned up loud. They all do the same thing only different

55mm 1.2 Nikkor SC the psycho girlfriend of lenses - fun in a bar wide open like doing shots of Chartreuse and running up a tab when you're broke. When it's good it's oh my god good the rest of the time it's just oh my god. Makes the camera drunk. Being able to shoot hand held by moonlight is fun too.

50mm 1.4 Nikkor SC pretty much normal and boring, less fragile than the 1.2 , less coma , less vignetting, makes everything look like news photography from the 70s. I've had one since 1973 and never liked it other than the fact that it was easy to focus. Good enough for Tri-x , a good lens if you only have one or three lenses with you.

50mm 1.4 SMC Takumar probably the best at 1.4 in the normal sense of best, not over corrected like the fast Nikkors No warts, only beauty marks. Kisses the mirror on the 5d at infinity , fine on the 1ds

50mm 1.4 Super Takumar Not quite as well behaved as the SMC but better build, less wirey than the Nikkor 1.4 though. I keep expecting to set off the radiation detectors around town with one

50mm 1.9 Schneider Retina Xenon best correction for longitudinal chromatic aberration of the bunch pretty sharp wide open. It's pretty wonderful It's My wide open trees in winter lens as of a couple months ago. Attracts European tourists.

58mm 2.0 Helios-44-2 pretty nice for $5 , sort of lumpy cat's eye swirly bokeh from the vignetting

50mm 2.0 Jupiter 8 Soviet Sonnar clone - Wide open makes everything look like Film Noir in black and white or Michael Mann in color, the most beautiful veiling flare that wraps around back-lighted people with headlights in the background. Focus shifts like crazy at 4.0 and pretty much sucks , but at 5.8 it is looking good , but still has a lot of personality. Will do until I find a 1.5 Sonnar or Nikkor . Nex only.

50mm 2.0 Summitar - interesting version of the lietz glow for street photos at night , probably wouldn't like to use it all the time , attracts Asian tourists. Nex only.

55mm 2.2 Auto Takumar ( stops down automatically then you have to cock a spring to re open it) It's *beautiful*. At every f stop it's almost another lens. Got it by lucky mistake momentarily confusing it with the 58mm 2.4

55mm 2.8 Micro-Nikkor Pretty much perfect in the conventional sense. Sharper at 2.8 than any of the faster lenses are at 2.8 I used it for a year only wide open because the diaphram was gummed up with oil then I decided I had nothing to lose and took it apart and cleaned the gunk out. Works great on the tilt adapter on the nex.

50mm 2.8 Schneider Componon S in some weird Leica helical mount that will focus it to infinity seems to be good but haven't gotten around to testing it. No interesting bad habits other than the really ugly diaphragm, but I want to try it for outdoor portraits. I've heard of mounts for these with waterhouse stops

55mm 2.8 Vivitar (Komine) Auto Macro Remarkably close to the 2.8 Micro-Nikkor $10 and sharper than any camera I've put it on, If I were forced to use only one lens I'd consider this one.

50mm 2.8 Zeiss Jenna Tessar in Exacta mount. I haven't done anything other than jury rig it to a couple cameras but it looks like it will be great , need to get a Topcon Exacta adapter.

50mm 3.5 Argus Cintar off my C3. Makes me feel like a 10 year old again. Definitely has a "look" but is *way* better than I expected. Nex only.

55mm 3.5 Micro-Nikkor P Lives on my slide and negative copier, if it's sharper than any of the 2.8s it's lost on the 5d2 haven't tried it on the nex

The Schneider Xenon , 1.2 Nikkor, and the Jupiter 8 are the only two I went out of my way to buy since I went digital, the rest are just the result of not getting rid of old cameras, stoop sales or in the case of the Micro Nikkors finding them in a dumpster. I'm still sort of looking for a 1.5 Sonnar or 1.2 Rokor and that should fix me for fast 50s

For what it's worth , the design of the different lenses seems to throw the canon light meter off one way or another , I haven't noticed that it is particularly tied to the f/stop. The Sony of course has no problems

Should I maybe have put this in the hoarding post?

[ctein]

Dear Folks,

Oren Grad just explained the facts of life to me.

I'm just plain wrong about screen brightness, for many SLR screen designs.

That'll teach me to get on my high horse, which has now been taken down a peg or two.

pax / abashed Ctein

[Voe]

The latest Leica M aspherical lenses are designed to be sharp and perfectly usable wide open.

[Carsten W]

One point I have not seen mentioned, and one potential reason to avoid fast lenses: focus shift.

Some designs cannot converge the outer rays to the same point as the more central rays (spherical aberration), and the predominance of one or the other can move the apparent point of greatest sharpness.

The end effect is that you may need to focus somewhere other than the place which seems the sharpest in the viewfinder. One recent lens famous for this is the Carl Zeiss ZF/ZE 85mm f/1.4.

Of course, if you are willing to deal with this (via rote learning, or live view, or whatever), you can get some great images.

[janekr]

I use Pentax 50/1.4 lens simply because there's NO new Pentax af 50/1.8 lens.
Neither there is no 50/1.7, no 30/1.8, nothing new, cheap and bright.

[Mike Johnston]

"why not give it a try? Put the camera up to your eye, press the DOF button and change the aperture to something wider than f/2.8."

Jack,
That's an interesting test, but it's a test of a fast lens at different apertures, not a test of a fast lens vs. a slow lens. I've looked into this a little bit more (and been lectured by a friend) and I do think you're partly right about the underlying technology (meaning, I'm partly wrong), but slower lenses have different geometry, different nodal points, and gather light from angles that aren't as acute as in fast lenses. If you want to test fast vs. slow lenses, the best way to do it is to compare a fast and a slow lens, not a fast lens at several apertures.

Mike

[Dave Stewart]

I note that http://www.slrgear.com/ has just posted a test on the Nikon 35mm f/1.4G AF-S.

Wouldn't mind one of those... between f/2.8 and f/11. Though I'll stick with the petite Voigtlander 40mm f/2 (usually from f/4).

[Andrew Burday]

I have not read all the comments here, so my apologies if this point has already been made. But surely one reason to buy the fastest lens, in some cases, is that that particular lens happens to have qualities that you like best -- even if those qualities have nothing to do with the large aperture. E.g. I know of an online photographer who only rarely eats crow who claims that the Pentax SMC Tak 50/1.4 is an exceptionally good lens. I certainly like mine, although I would use it at f/1.4 only as a last resort, because of the veiling flare. I have heard others claim that the Pentax 50/1.2s were the best Pentax K-mount 50s. At current prices, I'm not going to find out about that second claim.

This is another reason to buy (some particular) fast lens: because that lens happens to have desirable qualities, whether or not they have anything to do with the maximum aperture.

[ctein]

Dear Jack,

Yeah, I wrote my mea culpa's after Oren Grad e-mailed me.

The thing is, it's situational. Depends on the design of the focusing screen, for certain. Possibly also the design of the viewfinder optics and the lens itself. For every camera I've ever used, this effect wasn't present.

I was entirely wrong to be absolutist about it. But it is also not absolutely the other way.

Not so incidentally, this 2.8 business is not some kind of absolute number. I have no doubt the different screen manufacturers and screen designs use different aperture aim points. assuming the aim point is around 2.8 is likely to be a good guide, but consider it a rough rule of thumb rather than a hard and fast specification.

pax \ Ctein
[ Please excuse any word-salad. MacSpeech in training! ]
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-- Digital Restorations http://photo-repair.com 
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[Jack]

Mike,

"If you want to test fast vs. slow lenses, the best way to do it is to compare a fast and a slow lens, not a fast lens at several apertures."

I know that. This is just an easy way to demonstrate the viewfinder effect that you and ctein were disputing and have now accepted. Nothing more.

I like to have a fast lens as my camera is not so sensitive and it gives me more options, but at f/1.2 it is not easy to focus.

[Crabby Umbo]

Hugh Crawford!

I feel like printing out your comments and having them laminated! Putting them in my camera case...

You must be the king of the 50's! Especially like the 'psycho girlfriend of lenses'. Genius!

[Jona]

Mike made a comment about lenses being so sharp these days and not having any character. Since he opened that can of worms, I was going to ask about some of his favorite characters but I'm not sure our pocketbooks could handle the price increases that would cause. Hugh stepped up with some great input. I love it!

I think we need more characterful lenses. If I see a black and white photograph that is super sharp, then it just doesn't look right to me. But any new lens will be made for digital color these days. I'm thinking of trying as many tessar type lenses as I can for the heck of it.

[Phil]

f1.4 is the new f64.
Swings and roundabouts and trends. I have two 50's, a pre-AI Nikkor, and a newly acquired Pentax M. I like both, however the pictorial quality of the Pentax is a lot better than the Nikkor. I don't know, it just does things beautifully, and renders planes, both in and out, of focus in a very pleasing manner. It kind of reminds me of one of my favourite photographs, The Firefly by George Seeley.
It can be sharp too, however the sharpest lens I own is a nice old Mount 370 203mm 7.7 Ektar which is just fantastic, and can look incredibly modern, but open her up a bit (with a Prontor SVS) and she can look as old as you like.

[John Taylor]

'Aperture vs ISO, is there any real difference…'
Uhmm seriously? The differences would keep Ctein and Mike busy for weeks typing furiously had they and others not written extensively on this and related topics. Fortunately the can simply provide links and suggest some reading