Apertures Made Simple (Part I)

"If it sounds good, it is good."

—Duke Ellington

I'll definitely defend anyone's right to complicate things as much as they care to. But it still amuses me, I have to admit, when people complicate something that's essentially so simple.

If you want to get reliably good optical quality out of your lens, here's what you do: determine the best aperture for your camera and lens. Use that and the aperture on either side of it freely. (Those are known as "the middle apertures.") Depart from that when you have to, need to, or want to.

Voilà. Done.

No further complication necessary. Unless, as I say, complication is fun for you.

For full frame format (a.k.a. 35mm or 24x36mm), for me, the best aperture is ƒ/8. Ninety percent of the time, for 90% of [single-focal-length or "prime"] lenses, ƒ/8 is the aperture that gives me the all-around best-looking pictures, optically speaking. As usual, I figured this out empirically, i.e., by taking pictures and looking at them carefully, not by feeling the elephant's leg or pulling his tail ("testing"). You look at the whole picture, not just one little stupid aspect of it*.

So, for full frame, I use ƒ/5.6, ƒ/8, or ƒ/11 when I can.

...Departing from those apertures when I have to, need to, or want to. (I have to add that again, for the very few people who will forget I just said it and hence will want to argue with me as if I never did say it.)

The middle aperture changes with format. For 6x7 (cm), my middle aperture is ƒ/11; for 4x5 (inches), it's ƒ/22. For APS-C, 4/3, and Micro 4/3, it's ƒ/5.6. Think I'm wrong? No problemo; take your own pick. I'm not standing next to you with a ruler threatening to rap your knuckles if you depart from the gospel of Mike.

So then, what is the middle aperture for fingernail sensors? Like the ones in, say, the Canon G11 or the Pentax Q? That I don't know.

Mike
(Thanks to Scott Baker)

* Someone, somewhere, is bound to howl that I have no idea what I'm talking about, because you "have to look at" this or that property of IQ or you "have to measure in order to know." Actually, I know exactly what I'm talking about: for every property that that person fixates on, he's missing others that are of equal or greater importance to pictures, whether it be microcontrast, shadow detail, edge effects, tonal gradation, flare suppression, color differentiation, etc., etc., etc. A lens image is always a balance of many properties. Always. Look at images; look at the whole image; look, in the image, at the objects you're trying to image. In photography you don't get extra credit for resolving infinitesimally greater detail under ideal conditions; you get points if your pictures look better. (And sometimes not even then. Heh heh.) So look at the pictures and use your holistic all-encompassing sense of aesthetic discrimination—you know what a picture is supposed to look like, because you look at a lot of pictures; if your picture looks right to you, it is right. Don't let anyone talk you out of that.

UPDATE: Several commenters so far have agreed about ƒ/4 being the general sweet spot for fingernail-sized sensors.

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

Featured Comment by Jim Richardson: "Right on! 'Nuff said, as they say.

"And because I have some sort of perverse mean streak that comes out in the presence of camera brand orthodoxy, I have, over the years, engaged in a bit lens bashing. This usually occurs when someone insists (with reverent tones) that this or that particular lens is absolutely perfect, the greatest thing ever. Mostly they think this because it is a Nikon or Canon lens, sometimes because it is a Leica lens (more rare but also more virulent), and sometimes a Zeiss (rarer yet but the teutonic nasal overtones.)

"The gist is that the lens, in their view, is without faults. If the lens in question is a wide angle or a zoom of almost any focal length I know I've got them.

"So I then take them out do a very simple test (which works best in the autumn and winter, for reasons that will become apparent.) I point the camera up at a tree with bare branches agains the sky and take a picture. Then I reframe so that the same area of branches that was at the center of the frame is at the far corner of the frame. Then we go look at the pictures.

"Put side by side it is easy to see that the corner image sucks. The branches that had been nice and crisp in the center are now fuzzy with aberrations, fringed with color, weirdly stretched, or just otherwise crummy. Suddenly they can see that their prized perfect lens has feet of clay. (To be fair really good macros and long, expensive telephotos fare pretty well in this test.)

"Suddenly their world crumbles around them. And we can then start an honest conversation about working with real world lenses to get the best quality out of them that they have to offer.

"It's cruel, I know, but there it is. Sorry."

Featured Comment by John Camp: "I think I touched off Ctein's lecture on diffraction with a question I posed in an earlier blog entry. His answer was perfect: before, I had these vague worries about diffraction. Now I don't. Combined with today's column, I've dropped a lot of my photographic worries. To sum up: a guy like me, who doesn't really do art photography or super-high-res landscape photography, will be just fine if he sticks around ƒ/4, ƒ/5.6, or ƒ/8 with my Micro 4/3 gear, but if I need to go to ƒ/11 or ƒ/16 (or ƒ/2.8, for that matter), that's okay too, because I'm not the kind of person who'll be hurt by diffraction that can only be seen with a magnifying glass, or by a little corner distortion. Right? In other words, the fact that I hand-hold almost everything will cause me more (technical-photographic perfection) problems than diffraction or lack of edge sharpness ever will. Whew. Thanks."

Mike replies: Right. You got it.

Comments

[Douglas]

I would think that f4 would be your go to aperture for m4/3, and f5.6 would be for aps-c, no?

[Fernando]

That's pretty much what I do. I also like pentax's MTF priority program line, wich with any FA or later lens gives you the best aperture based on MTF data -communicated by the lens to the body (and for older lenses I think closes one or two stops from wide open)

[Eric Ford]

It is definitely more complicated for me, but my "rules" have come from experience, too. I hate math anyway. For landscapes, group pics and "scenes" where I want everything in focus (35mm format), f/8 or f/11. For individual portraits, things start to get hairy. I find a wide-ish portrait at say 35mm, I want f/2 to isolate the subject, but at 85mm I need more like f/4 or 5.6 to keep their whole face/head in focus.

[Ger Lawlor]

Mike, If I read you correctly, the optimum aperture relates to the design distance from the rear element of the lens to the film (or sensor) plane, and not simply to the focal length, e.g. a 35mm 200mm lens will have a different optimum aperture than a 4x5 mm 200 mm lens (everything else being equal, of course)??

[Andreas Waldeck]

G11: f4 , empirically tested... ;)

Andreas

[CK Dexter Haven]

I don't understand.
You're predisposed to shooting at f8, simply because that's the aperture at which your gear performs best... but you're letting the equipment dictate the 'aesthetic content' and characteristics of the eventual image? Does the world really 'always' look better at f8, regardless of the focal length of the lens or the subject matter? Portrait with an 85/1.8 - shoot it at f8. Landscape with a 21mm - shoot it at f8?

I know you're not making a 'rule' here, but that's almost what it sounds like. The physics determine how much DOF you WANT?

[Alex H.]

Wouldn't light and the subject determine the aperture? For instance: if I want to take a picture of my son without motion blur I need a 1/60th of a second exposure. In a so-so lit room and my M8's max usable ISO of 640 (my opinion) I need f2.0 or f2.4. In brighter light it's a decision of depth of field and ISO (while I tend to use ISO 320 and a somewhat larger aperture to be able to compensate for focussing errors).

For me, it's as simple as that. I have not ever thought about diffraction limits or determined the "best" aperture of my lenses. I just concentrate on the moment and try to get the exposure as right as possible. Some of my best shots are straight into the sun at f2.4 or 1/4th of a second f5.6 exposures that are somewhat blurred by camera shake or subject motion. But they do capture the moment (at least for me, opinions naturally may differ). I wouldn't have been able to capture most of them if I had worried about best aperture or diffraction limits.

[Jim Natale]

Excellent, direct approach. Would add that for the APS-C DSLRs I typically find that--similar to the 4/3 and Micro 4/3 formats--the sweet spot for a wide lens (or the wide part of a zoom's range) tends to be at 5.6 and 8, while the longer focal lengths tend to be better at 8 and 11. (I acknowledge that some super lenses are great wide open, overcoming typical limitations, but for 99 percent of photographers and their equipment, in 99 percent of their shooting situations, your approach is the one they should use 100 percent of the time.)

[Mike Johnston]

CK Dexter Haven,
I'm talking about when you want to get the best optical quality out of your lens, that's all. This is an extension of the discussion yesterday about diffraction effects at small apertures on small sensors. I assumed that was clear....

Mike

[Gary Brown]

Somebody should make a list of all the things we need to know from a photographer before we can decide whether we like his photograph.

Besides asking the obvious "What aperture did you shoot it at?" how about: Did you use a tripod? Was it taken within one hour of sunrise or sunset? Did you use a zoom lens or a prime? Was it a raw capture instead of JPEG? What software did the raw conversion? Were you in manual mode, aperture priority, or what? If autoexposure, what metering mode? Autofocus or manual focus? Did you select a focus point or focus and recompose? Etc.

I can't tell you if your photo/print looks good or not until I know the answers to those questions.

[Clayton Jones]

"So then, what is the middle aperture for fingernail sensors? Like the ones in, say, the Canon G11..."

Long time and happy G11 user here - it's f/4.0 What a great camera!

Also agree on f/5.6 for m43. I'm using an E-PL2 now for 6 months and that's definitely the sweet spot.

Regards,
Clayton

[robert p]

Yeah well, you can prove anything with facts can't you ?

[Nick]

Thom Hogan suggested a while ago that three aperture settings do most of what most people want to do: maxium light collection, best quality, and maximum (reasonable) depth of field. For my camera and lenses, f/8 seems cover both of the latter criteria well enough that I rarely depart from it in daylight. So, there are really only two aperture settings that I use regularly. Perhaps the lovely little thumbwheel on my camera could be replaced by a single toggle...

[Rick in CO]

Wasn't there an old saying "f8 and be there!"?

[Rob Atkins]

A senior Nikon tech person once told me, quite empirically it seemed, that with any optic it's always 'the middle of the lens' that's the sharpest. With a 2.8 lens, f/8 would be sharpest.

That said, I just bought the Nikkor 50/1.4 and have been shooting a lot at 1.4. Not too sharp, but pretty - everything looks nice through that lens.

Rules were made to be broken...especially for us contrarians, eh Mike?

[Winsor]

I am kind of amused by the irony of the disagreement with CTEIN on the same page and it is his print you are selling. Of course his preference for F4 is tied to good lenses in his text.

My simple rule of thumb for sharpest aperture is three stops in from wide open and the apertures on either side of that. Apparently you only use F2.8 lenses while he uses F1.4 lenses.

[Tony Roberts]

M: Thank you for saying what I like to teach. Find "your" best aperture and use it whenever possible. And get a tripod!

[JK]

The "enthusiast" crowd probably won't buy such a simple idea, but pretty often these are also the apertures that make the photo work best too.

[Jay Frew]

Careful Mike, if you convince enough folks that this stuff doesn't have to be complicated, you could have a negative impact on photo equipment sales and lose sponsors. Think about it for a moment. If people were to discover that they were happy with what they had, why would they buy more stuff!

;~))

Cheers! Jay

[Steve Jacob]

Shucks. So thats why every shot I take with an APSC camera with my travel zoom seems to be at F7.1?

I admit though that unless I am using a heavily compromised lens, I generally worry only about DOF and (in extremis) shutter speed when selecting aperture.

In a dark concert hall, the centre sharpness of my 70-200 F2,8 is sufficient wide open to use it in preference to either higher ISO or lower shutter speed. That is the value of a good lens.

However for most of my prints (A3 or 19X13) most of my decent lenses produce excellent results between 1 stop from wide and around F16 on a D700. At least, to the extent that bokeh, contrast, distortion and post processing are more important factors than sharpness.

If I was printing much larger prints with a 40MP back I may be more considered, but this is not a situation most contributors to gear forums (and the biggest gassers about lens quality and sharpness) ever find themselves in.

"Give a man a sharp lens and he is happy for a day. Teach him to use USM properly and he is happy forever ;)"

Choose a portrait lens for bokeh and don't sweat about sharpness - choose a landscape lens for evenness and contrast stopped down and dont worry about bokeh - choose a zoom for versatility and accept a loss in ultimate performance. Use the tool that fits the job and stop looking for perfection.

Now, anyone know what the perfect car is?

[Marc Rochkind]

OK, right, so I'll just keep using f/32 when I feel like it. ;-)

[Bill Bresler]

Generally, my cheapest lens, at any f-stop, is sharper than my photographic vision.

[Hugh]

I like f2.0

[ctein]

Dear Winsor,

That's entirely wrong! On several levels.

1) I never, ever said I preferred f/4. I said that peak lens sharpness often occurs between f/4 and f/5.6. That is NOT what Mike is talking about.

In fact, upon reading Mike's column, I was amused (and pleased) to observe that I favored almost exactly the same apertures as he did. It was almost an unconscious process. I wouldn't really think about it much... but if I had, the mental conversation would have gone something like...

"Gee, I'd like to set the aperture to f/8. OK, is that giving me enough depth of field for what I want for this photo? No? I better stop down. Oh wait, is my shutter speed getting too low? Dang, I better open up a stop or three."

I'll bet the majority of my good photos were done with no more complicated thinking than that.

2) Mike clearly said to use what ends up looking right for *you*. So even if I had said I favored f/4 (and, again, I didn't), we wouldn't be contradicting each other. No more than it's a contradiction that he prefers, on average, wide angle lenses while I lean towards telephotos.

3) If there's one single thing that I would hope readers have learned from years of columns by both Mike and I, it is that we do NOT think that technique makes the photograph. Even if all the photos that were in the current TOP offer grossly violated this guideline, it would be neither amusing nor ironic.

A rule of thumb is just something that works far more often than not. It is not a metric by which you can judge the success of a particular photo. Conversely, the success/failure of a specific photo does not in/validate a rule of thumb.

pax / Ctein

[Kenneth Tanaka]

I agree with the basic carrier message, Mike. The actual impact of small increments of aperture change is trivial with today's optics.

Most folks would be far better served devoting their attention more toward composition, timing, and just putting that lens someplace other than face-level. Folks also do much more damage to their images via heavy-handed digital post-processing than any aperture setting could ever do.

[ctein]

Dear Mike,

I am intrigued that my "intuitive apertures" mirror yours almost exactly. Great minds lying in the same gutter, I suppose...

FWIW, when I had my "thumbnail" sensor cameras (really more like pinky nails), I settled on f/4 as the sweet spot.

pax / Ctein

[John Anthony]

Hi Mike,

Nice article. I just want to add something related to m43 format: please try f/6.3 as the sweet spot. There is no big difference between f/5.6, f/6.3 and f/7.1, but f/6.3 gives the most detail of them all.

Best regards,
John Anthony
m43photo.com

[David Dyer-Bennet]

You're absolutely spot-on dead-center right about the really important bit here: the only meaningful measure is the results in actual picture-taking.

The theoretical stuff is vastly important -- for lens designers, in particular. The theoretical stuff (to the extent that our understanding is correct, but we're fairly good at ordinary optics these days) is the "final answer" in the physical sense -- but we don't know how precisely our given camera and lens and sensor conform to the model we're computing. I also approve of having some theoretical understanding even if you don't absolutely have to to take pictures (and you don't). But getting overly involved in it is irrelevant to picture-taking.

And your basic approach is unworkable, even irrelevant, to me. The percentage of my total pictures that are at f/8 or smaller is going to be in the low single digits, and that includes travel snapshots (a big percentage of my outdoor shots). I think of f/2.8 zooms as slow lenses; they're among the slowest I use.

[Mike Johnston]

"Now, anyone know what the perfect car is?"

That's easy. Arthur Herrmann and Klaus Kutsche's 2006 BMW 2002tii.

http://www.theautochannel.com/news/2006/03/31/002626.html

Close second: an NB Miata with a Flyin' Miata makeover, suspension, chassis (frame rail reinforcement and butterfly brace), rollbar, and exhaust mods mainly. But NO turbo (<--heresy).

Mike

[LM]

I think the message behind this (rather odd) posting is revealed by the fact it's labelled "Part I"

[Hugh Crawford]

"The gist is that the lens, in their view, is without faults. "

That's funny, I seem to have been on a lens buying binge the last few years and it's the flaws that I'm interested in. So naturally I'm most interested in shooting everything wide open because that's when they look the "lensiest"

A few years ago I had dinner with a big time DP and his focus puller and the consensus after a couple hours of conversation that started with "what's your favorite f/stop" was 5.6 for flat lenses unless you are doing a dolly zoom or shooting in scope where you need as much DOF as possible.

[CMS]

I agree with f/8 being the best aperture in FF most of the time, and stopping down to f/11 doesn't change a lot apart from giving better corner sharpness.

Where you can see a big difference between lenses is when opening up from that best aperture. It came quite as a surprise to me that the Nikkor 35/1.4 AF-S kept a very high image quality at larger apertures such as f/4 and f/2.8, beating hands down lenses such as the 35/2 AF-D or the 17-35/2.8 AF-S of the same brand when used at the same large aperture. (It is also superior at f/8 as far as corner to corner sharpness is concerned.) That prompted me to revert to prime lenses, mainly as it extends the low light capabilities of the D700 in a substantial way.

Mike, perhaps you should reconsider your aborted attempt to test that 35mm lens.

[Mike Johnston]

"To sum up: a guy like me, who doesn't really do art photography or super-high-res landscape photography, will be just fine if he sticks around f4, 5.6 or 8 with my m4/3 gear, but if I need to go to f11 or f16 (or f2.8, for that matter), that's okay too, because I'm not the kind of person who'll be hurt by diffraction that can only be seen with a magnifying glass, or by a little corner distortion. Right?"

Right. You got it.

And beyond that, you "learn your lens" (or lenses). If you repeatedly find yourself dissatisfied by wide-open shots, or find that shots made with the smallest aperture are distinctly soft, then you avoid those apertures when you don't want those effects. Learning a lens can go much further than that, of course. But basically, you just pay attention to what you see in the pictures and, when you get a bad effect, see if you can track it back to your technique.

I'll give you an example. The one time I had to hire a chopper as a pro, it was to do some shots for a real estate company. I took all the shots I could think of in fifteen minutes, and had fifteen minutes of air time left. So I asked the pilot to go to the beach, where I took some shots straight down on the beach. Because this made me lean uncomfortably far out of the helicopter, I changed to a higher shutter speed. I figured it wouldn't matter because the plane of focus was flat...the beach. But I didn't know the zoom I was using, and unbeknownst to me it was soft in the corners at its widest two apertures. I was closed down only one stop. It made a difference on the beach shots because there were tiny figures in the corners of all the frames. If I had "learned" that lens in the sense I'm talking about, I would have stopped down one more stop for the beach shots. As it was I solved the problem by cropping the edges off the beach shots, some of which worked okay cropped.

Fortunately in that case the money shots were fine, because there was no important detail in the corners in those shots--nothing to draw attention to a little softness. "Better to be lucky than smart," to quote one of my father's favorite expressions.

Mike

[Steve Jacob]

@Mike

Re: BMW 2002tii. My camera equivalent would be something like...an OM10?

As for a Miata, that would be like a Pen EPL3 (Lite) perhaps - stick the 24 on and it's like adding the V8 ;)

My trusty D700? A bit of a all rounder, but one with some go, perhaps a Subaru Legacy Outback?

But the BEST car? Surely that would carry a family of five, tow a boat, take you camping in the hills and still hit 60 in under 6 seconds. A Porsche Cayenne? Leica S2?

[Jim Bullard]

In 54 years of photographing I have to say I have never given one thought while shooting to what the "sweet spot" of my lens is. I focus on the most important detail and use the aperture that gives me the DOF that I want. I've seen all the articles on bench tests with targets that look like the images that a TV station showed when they were off the air (you do remember that I said I'd been doing this for over 50 years) but I never take photos of test charts so that no meaning to me. Content is king. If you have subject matter that engages the viewer they aren't going to be pixel peeping anyway. Spend more time trying to engage your audience and less time worrying about whether each image is the absolutely sharpest you could manage. If the comments you are getting are "that isn't quite as sharp as it could be" you are missing more than what is your sharpest f/stop.

[Will Frostmill]

Well, Mike, this was really helpful. I had come to a similar conclusion a while back, but it is always nice to hear you and Ctein confirm such things. (And it is interesting being in the same camp as John Camp!)

My own experience has taught me that the most important thing by far is an accurate AF system (85% important), followed by less high iso noise (10% important), with pointing the camera at the right thing, getting enough DOF, and having an adequate shutter speed making up almost all the rest. Diffraction effects and/or corner distortions are a rounding error by comparison. I will cop to usually working with less than 5.6 on 4/3rds, since for most of what I do I'm in low light, and more depth of field than you get at 5.6 causes far more problems for me than it solves.*

*I'm doing a lot with the Olympus m34 14-42, set anywhere between 17mm and 25mm, which means f/4 to f/4.5 wide open, which is plenty deep and plenty sharp. Probably the best range for that lens anyway.

[Gary]

I was 8 (34 years ago) and my brother handed me his minolta xg-1 with 45mm Rokkor and showed me how to focus and told me to leave the top dial on 'A' and to leave the lens dial on 5.6.
Worked great!

[Hugh Crawford]

The reason Mike isn't running a photo hardware blog is because every time it veers towards the hardware it runs completely into the ditch and ends up being about cars.

Re the perfect car:

Porsche used to advertised the Boxster, their only non racing two seater*, with the slogan "the more children you have, the more practical it is."

*Even the other mid-engine, the 914, was officially a 3 passenger car--something about German tax law. The third seat is a 8 x 20 pad between the two seats complete with seatbelts.

[erlik]

Interestingly, the highest-grade 4/3 lenses are apparently optimised to be best at the widest apertures or closed down just a bit. I say apparently because I've never given it much thought but just saw sharpness tests. Otherwise, I can only say that I don't have much fear about shooting wide open.

[Steve Smith]

Yeah well, you can prove anything with facts can't you ?

94.3% of all facts and statistics are made up.

[Jacques Pochoy]

Ah... Some wisdom from the "big shots" ! When much younger I discovered that f/5.6 was an excellent compromise (for me) between D.o.F., speed, and hand held focusing (when you don't have time to focus on the white of eyes...).
In those times we were still playing with hyper-focal to catch that nice lady at the café terrace and we thought we had to be quick and discreet, following H-C.B's advices on the Japanese archer riding his horse...
Since the FTb QL time and some long gone films, the latest digital tools hasn't really changed that viewpoint (even with a D3x). Subject and composition still dominates whatever the technical tidbits from then to now...

And many thanks to Ctein for trying to be the great peacemaker in the everlasting media war !

[Allan Graham]

Rob Atkins,

Yes! Nikkor 50/1.4, wide open . . . perfect satin softness!

[Robert Roaldi]

People worry way too much.

[John Krumm]

No way f5.6 is best for 4/3 sensors. After extensive trial and error I have determined that f4.5 is best. : ) Actually, for me, this is somewhat true when shooting people at medium distances and medium focal lengths (20-35mm), especially using the very sharp Oly 12-60 lens. I think most of it, though, comes from the depth of field being just deep enough for groups, with just a hint of blur farther back. It's a look I like.

[Mike Johnston]

Jacques,
Just as an aside, I am definitely not a "big shot." I think of myself as the nomad equivalent of a high school photography teacher. And grateful to have this semblance of a job....

Mike

[Mike Johnston]

"People worry way too much."

Worry is "paying a bill that hasn't been tendered."

(What, me worry?)

Mike

[Brad Nichol]

My students have a running joke with me about my being Mr f7.1, what aperture should I use here Brad? F7.1 is the standard answer for everything, well of course there are plenty of alternatives for certain situations but it works well so often to help students get the shot with little fuss and it is indeed my favourite aperture.

Most lenses work pretty much optimally at this setting and most lens problems are at their least bothersome, focus is nowhere near as critical.

But I have other good reasons as well, I encourage people to learn to expose by eye using a version of the sunny 16 rule, except it is the sunny f7.1 rule, this generally gives with 100 ISO 1/500 sec at f7.1 as the base, shutter speed calculations up and down from there are a cinch and results are actually often better than what the camera meters come up with.

F7.1 also works pretty well for DOF, for teles it is enough to get a face fully in focus or an action shot reliably sharp and in focus without going to too slow a shutter speed, for shorter lengths its gives an extensive enough DOF to give the result we are often after when going to wide angles. For standard focal lengths it is an aperture that works well as you move in and out to control DOF framing and perspective.

Generally shutter speeds end up in a range that ensures minimal blur even at 100 ISO and it if the light drops off just raise the ISO a bit.

Over many thousands of images I have found that it is my most used aperture, most certainly not the best for everything, not a rule and not perfect but surprisingly right for so many situations with so many lenses and cameras.

[Doug C]

I've been shooting a lot over the last few weeks at f5.6, (D700 and 50mm f1.4) and I must agree, f8 would have been a bit better in almost all cases, and I could have bumped up the ISO to 400 to cover. Thanks. I'll give it a try.

[Loïc lacombe]

My nikon 50mm f/1.4 is kinda soft at 1.4 and I especially like it for that characteristic. I do agree, I don't care about the aperture, the sharpness, the micro contrasts, I only do care about the depth of field and the magical sweetness of my gear.
Let's call it magic with little gnomes in it and I'm happy.

[Rip]

For those who think that keeping it simple is too ... simple ... try this:

http://www.luminous-landscape.com/essays/csm_image_quality.shtml

[Jason Davidson]

Dear Mike

Thank you for this article. Although I sort of realised the principle of the article in the back of my mind, I had never really considered it in my day to day shooting. What I now know is that I need to test my cameras and lenses and stick to the middle apertures where possible.

What I would like to ask you though (and I apologise if this is already destined for a Part 2) is how do you determine when to stop down the aperture from the optimum to increase the depth of field. I realise that there are thousands of Depth of Field tables to download on the internet, hundreds of Depth of Field apps for your iPhone or Android that will calculate these figures to an improbable level of accuracy but I am asking for any little tips and techniques that are practical to use when out of a little casual walkaround, especially in this day and age of no distance scales on camera lenses. What I am trying to ask is whether there any particular numbers, distances etc. that you keep in the back of your mind for a particular aperture and focal length so that you know to stop down to gain a little further depth of field throughout the image.

Or am I just complicating this issue (further!) and should just look at a scene and think "a lot needs to be in focus here" and stop down one or two stops accordingly?

[Mike Johnston]

Jason,
This isn't going to be immediately helpful, and it's the kind of answer that drives the measurbators crazy, but I think you just have to learn by experience. In the early days you'll find yourself chimping a lot, but eventually you'll get the feel of what's needed when. Learning your particular lens helps a lot.

Mike