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Tuesday, 15 September 2009

Comments

Looking forward to the rest of the review. Couldn't help notice that where you write "because of the K-7’s 1.5X crop factor, a 50–135mm becomes the functional equivalent of a 70–200mm ƒ/2.8 on a full-frame camera" it should be "equivalent of a 70–200mm ƒ/4". Depth of field suffers about a stop in the transition, if I'm not mistaken.

Nice photos, BTW.

It just so happens I stumbled on your blog before through the Pentax Forums site, of which I am regular contributer in the 'post your photos' section. I have and bought a Pentax K10D One of the reasons I bought this camera was because I could not afford the bigger names like Nikon and Canon. I have a substantial investment in older manual Nikon lenses and was hoping that Nikon would put out a camera that was interchangeable with my older lenses (I know Nikon now has this, but too late for me!. At the time 2007, Nikon did not have such a camera and I needed a digital camera to take on vacation. So I researched and bought the Pentax K10 for two reasons: One it was a good DSLR at a good price; two, it is compatible with all its older lenses which I could acquire relatively cheap. The only issue I have is with its non-100% viewfinder coverage, which really bother me since I was film slide shooter for years. I am sure that you will cover this feature in the new K7 and its reportedly better ISO performance at all levels. Circumstances led me to the Pentax brand and I have to say, I am happy with the K10D. But I am not a fan of any one brand. It just happened that way. Am enjoying your review so far and look forward part 2. Now, what to do about all those Nikon lenses...

JMR

Thanks for the review, I've been looking forward to this. I have a soft spot in my heart for Pentax as well.

I do hope that the obsequious ass-covering disclosure goes away soon. I find it distracting. I trust TOP (and LL, and Reid Reviews, if it came to that) enough to do away with this annoyance.

great shots gordon, esp last one, look like canvas painting

"...it should be 'equivalent of a 70–200mm ƒ/4'."

No, it shouldn't. An f/2.8 lens is an f/2.8 lens even if you have it mounted to a view camera or you're holding it in one hand and casting its image on your other hand. Its max aperture doesn't change with sensor or film size.

Mike

Thanks for this great intro and your wonderful shots; the woman with the umbrella looks like a painting, so perfect is the composition. Just fantastic.

I have a soft spot for Pentax, too, but as I was waiting for the K-7's price to dip, Sony dropped the A850 bomb, and I bit. It's a big beast, but no looking back now. Maybe I should skip the rest of your installments... :)

"...it should be 'equivalent of a 70–200mm ƒ/4'."

"No, it shouldn't. An f/2.8 lens is an f/2.8 lens even if you have it mounted to a view camera or you're holding it in one hand and casting its image on your other hand. Its max aperture doesn't change with sensor or film size."

"Depth of field suffers about a stop in the transition, if I'm not mistaken."

i think Robin is right about depth of field has realative EV around -1.2 effect on aps-c but yes it's still 2.8 aperture lens

Mike,

you're of course right that an f2.8 lens is a an f2.8 lens regardless of sensor size for light gathering purposes. But, I believe you would need a stop faster lens with the 1.5 crop factor to get the equivalent smaller depth of field for subject isolation compared to a "non crop" 35mm sensor size.

I agree with your basic premise of lens quality as a very important factor in image quality.

The first lens into the camera bag is my DA* 50-135mm f2.8.

While the K10D has a Carl Zeiss 35mm Flecktagon mounted, and I am set for walking around.


The lenses supplied for test are good but not Pentax's best.


The DA* range and the Limited primes would really show the true ability of the K7.

"...it should be 'equivalent of a 70–200mm ƒ/4'."

No, it shouldn't. An f/2.8 lens is an f/2.8 lens even if you have it mounted to a view camera or you're holding it in one hand and casting its image on your other hand. Its max aperture doesn't change with sensor or film size.

I wonder if Robin was referring to its depth-of-field (that is, it would have more depth of field, more like a FF f/4 than a FF f/2.8) rather than its light-gathering ability?

Hey Gordon,

I just went to your website and I really like your color abstracts!

I'm a dual system Nikon and Pentax user. I love my six Pentax limited lenses and have been eager to get at K7. The only thing that is holding me up is the lack of dynamic range at low iso's of the K7 as compared to the sensors in the two year old Nikon D300 and the D90 (reportedly 1-1.5 stops worse in the K7). When I got my D300, I immediately noticed the dynamic range improvement over my Pentax K10D and the K7 has slightly worse dynamic range than the K10D. This is the one area where the K7 seems lacking and I hope you comment on it in the upcoming installments of your review.

"it is compatible with all its older lenses which I could acquire relatively cheap."

This may be true of the Pentax K10D but it's not true of the K-7. Although you can physically mount older manual focus K-mount lenses (often referred to as "K/M mount") onto the K-7 they won't communicate with the camera and the camera won't allow you to release the shutter, no matter what exposure mode you use. I know because I tried.

According to the K-7 manual the only compatible lenses are DA, DA L, DA FA, FA J, and lenses that have an A (aperture) position on the aperture ring, and then only when the lens is set to A. That's still a considerable number though and excellent used Pentax lenses are available at bargain prices.

I am probably wrong as well, but I would write "Depth of field improves...."

JMR: Where did you get the idea that Nikon didn't have a camera compatible with your older manual lenses? I was using my 1980s AIS lenses on my Fuji S2, and they worked just the same on the Nikon D100, in 2002. All the Nikon digital cameras, and the Kodak DSLRs before them, have worked with Nikon manual focus lenses. (Pre-AI lenses needed to be AI-converted, but that's been true for a LONG time now, and it's an easy conversion.)

"...it should be 'equivalent of a 70–200mm ƒ/4'."

No, it shouldn't. An f/2.8 lens is an f/2.8 lens even if you have it mounted to a view camera or you're holding it in one hand and casting its image on your other hand. Its max aperture doesn't change with sensor or film size.

Mike

-------------------

Mike - I think Robin's comment was a subtle reference to your prior venting on depth-of-field and sensor size, n'est pas?

Great to see this review! The K7 is a camera I have a lot of interest in, and it is good to see a review from Gordon. I have been reading his blog for the past six months or so, and really enjoy his writing style and perspective.

Looking forward to the rest of the review.

Jim Couch

"Although you can physically mount older manual focus K-mount lenses (often referred to as "K/M mount") onto the K-7 they won't communicate with the camera and the camera won't allow you to release the shutter, no matter what exposure mode you use. I know because I tried."

Gordon, I just mounted an M42 lens using a K (non-A) adapter on my K-7 and it worked just fine. I have also read several reports (and seen shots) of people using K/M lenses directly on the K-7.

As was the case with the K10D, "non-A" lenses must be used in M mode, with the Green Button used for stop-down metering (one must also set Custom Option "38. Using aperture ring" to "2. Permitted"). Av mode can also be used, but the lens will remain wide open no matter the position of the aperture ring.

If this doesn't work with your K-7, I would guess that it is defective.

The 50-135 is an amazing lens. I have the Tokina version for my Canons.

And I will say I am one of those wanting to convert. It's just the cost holding me back, and well, the AF system of the 7D. I'd LOVE to have an army of pancake lenses to use.

On the similar note though, my desire for the K7+pancakes has dwindled some with the GF1. I decided to preorder it since compactness was a key. A K7+40/2.8 is small, but still quite bulky.

But I do hope Pentax stays alive over the next few years and keeps innovating. When my 40D grows old, I may just have to switch.

Gordon:

I'm a big Pentax fan and have been since I got a Spotmatic in 1973. I'm still waiting for the 645D. So, I'm happy to see a review to help this brand (not company, that has changed) through troubled times. I regret to say that the images you posted would likely convince me to look at Sony or, heaven forbid, Canon as I transition to digital (my "serious" camera is still a 67II). They are all very soft. The first two, at slow shutter speeds, are understandable, but the rocking chair? I look forward to the remainder of your review and hope it illustrates what Pentax or Takumar lenses can produce.
On a more positive note, I visited your website and found the abstract gallery amazing. It reminds me of Pete Turner and that, at least from me, is a high compliment.

Tom (Pentax and Pete Turner fan)

Having had a Pentax MX back in the 70's with their 28mm, 40mm pancake, and 100mm lenses, the new K-7 is very appealing especially when coupled with their "Limited" primes, and almost makes me want to drop the large(by comparison) Nikon setup and get back to the smaller and more toteable kit that drew me to the MX in the first place. About the only thing holding me back is the 85mm f1.4 AF-D :)

Mike, I think Robin's point was that the depth of field of a lens at f/2.8 on a 1.5x crop sensor is approximately the same as the depth of field of a lens at f/4.0 on a full-frame sensor, with the lens to subject distance kept the same and the focal length adjusted for the crop factor. This can be verified by one of the online depth of field calculators. If one desires a shallow depth of field for portraiture, this would make a difference. In terms of the exposure, however, you are absolutely correct - f/2.8 is f/2.8 regardless of the sensor size.

"I regret to say that the images you posted would likely convince me to look at Sony or, heaven forbid, Canon as I transition to digital (my 'serious' camera is still a 67II). They are all very soft."

Thomas,
With digital, some degree of sharpening is normally added in post-processing, but it's conventional to show out-of-camera JPEGs in tests without any added sharpening. But it's not like it is with film, where it's basically built into the equipment. You can sharpen your pictures to your heart's content. We could make these pictures look a lot sharper on your monitor, but that wouldn't signify anything meaningful.

Mike

The test images suggest great things are possible in low light situations with this camera. Here's a plea: can we get a complete review of the viewfinder (size, quality, ease of focus w/legacy MF lenses)? I readily acknowledge it's a pet peeve of mine; but when I looked at the K10D, I really felt that the VF paled in comparison to the Canon 5D and the Nikon D3 -- for me, accurate focus of non-AF lenses is a must for any system. Thanks for a fresh look at a new camera.

Ben Marks

Gordon,
When you set the custom menu feature to "using aperture ring - permitted", you can use a lens set to any manual aperture. In manual exposure mode, you press the green button, the camera will set a shutter speed appropriate to the aperture set.

"The only thing that is holding me up is the lack of dynamic range at low iso's of the K7"

It's one thing to read about "lack of dynamic range" in a lab report. It's another to see it in actual photographs. In my opinion the photo of the rocking chair on the porch is an example of a high contrast subject that displays adequate shadow detail in the photograph. I've used other cameras that definitely would have shown less. That said, it's something I'll be on the lookout for.

What's going on with Pentax lens prices in recent months? I just took a look at B&H Photo and the 31mm has jumped from $800 to $965. The 43mm has jumped from $439 to $570. The 40mm f2.8 has jumped from $250 to $340. And so on. It seems that many lenses are up about $100 over what they were a few months ago.

"JMR: Where did you get the idea that Nikon didn't have a camera compatible with your older manual lenses?"

Thanks for that info David Dyer-Bennet. I had no idea. I was told by the saleperson that the Nikons of 2007 (newer models I guess) did not take the older lenses. I only have AIS lenses which are not that old. Anyway, I will decide between the Nikon 700 and the K7, even if I have to buy them used. I can't afford two systems.

JMR

"Although you can physically mount older manual focus K-mount lenses (often referred to as "K/M mount") onto the K-7 they won't communicate with the camera and the camera won't allow you to release the shutter, no matter what exposure mode you use. I know because I tried."

As Richard Bellavance pointed out, the crucial step in using manual lenses is to set the custom option "Using aperture ring" to "Permitted", which I believe is necessary on all Pentax DSLR's (I have one of the earlier ones). I have absolutely no idea why this option is not enabled by default, though.

Gordon: Thank you for an excellent article. I'm very much looking forward to the next part.

I've never touched a Pentax camera but your remarks thus far tell me that I'd be remiss if I didn't give the K7 a look if I was in the market. (Being up to my shoulders in Canon and Leica I don't think it will happen soon but ya never know!)

Separately your color abstract work (it's actually not truly abstract, more like geometry studies) is simply top-notch stuff. Really. It's wonderful stuff that I hope you plan to publish and/or exhibit if you've not already done so.

K-7 have a long time exposure problem: in bulb mode, if exposure time is greater than 30 seconds the noise reduction automaticaly start. This make unusable the camera for a time equal with the exposure time.
Previously I have a K10D where I can turn off noise reduction. This feature is important for night photography with star trails.

Didn't read a word of the article but the picture of the lady with the brolly is terrific.

The K-7 is fully compatile with any k mount lens (or m42 lens with an adaptater). I'm using regularly a Vivitar 28mm f2, a Zenitar 16mm, a Pentax M-100mm F4 macro and a pentax K135 F2.5. All are fully manual, not A position.

Thanks a lot for an outstanding article, Gordon; up to the levels we expect from The Online Photographer, which is saying.

I appreciate a lot your clear description of your personal tastes regarding photography, and I'm really looking forward to your next statement in the review.

Now let me end by saying that all three pictures look fantastic, but in particular your picture of the lady under the umbrella is absolutely magnificent.

Great review of a remarkable camera, looking forward to part II! A week ago I bought a K-7 and sold my D700 and Nikon prime lenses. I know, some people will think are you crazy?

After using my D700 for a year I reviewed my Pentax *ist Ds and K10D pictures, owned these camera's before D700, and was stunned...these pictures were great, great color, DOF and detail. I thought I needed full frame, autofocus etc. The quality of my pictures decreased while they should have been increased after spending all that money and a superior camera..what was wrong?

My D700 and Nikon primes were 3 times more expensive....is that worth all the money and does that refexts in my pictures...?

After studying these pictures I found out why they were so great. I took these Pentax camera's everywhere..sand, snow, water didn't matter. And the quality of the old Pentax primes is great, much more character than the new autofocus Nikon primes. And when I bought my D700 I thought the DOF and Bokeh would be soo much better on a full frame camera..what a mistake. The high ISO on the D700 is great....but I rarely shoot above 800 ISO...with not much light the photo will be crap anyway.More and more I kept my D700 at home, it is a lot of money...but above all..it is heavy.

Now I am back with Pentax. A K-7 and 3 manual focus SMC K-mount primes (to Jeff Kott: of course you can use the old primes on the K-7)

The quality of the K-7 images is great! I am spending more time now per photo. Composition...great with 100% viewfinder and while manual focussing you think more of your composition. Manual focussing is easy with the bright viewfinder

Most important I take my camera everywhere..I is in my backpack and almost don't notice it amongst all my other travel stuff. With the D700 it was the other way around...way to heavy and you take it out and everybody thinks you are a pro...the K-7 is much less obstrusive. I can tell you my picture are already improving and most important I have more fun. Less is more! and the K-7 is built like a tank.

Gordon, I was glad to see that you wrote, "a 50–135mm becomes the functional equivalent of a 70–200mm" rather than just, "a 50–135mm becomes a 70–200mm".

I see the second statement lazily repeated again and again in magazines that know better.

It must be very confusing for new photographers, who rely on these magazines to get the technical details right.

Well done that man!

"As was the case with the K10D, "non-A" lenses must be used in M mode, with the Green Button used for stop-down metering (one must also set Custom Option "38. Using aperture ring" to "2. Permitted")."

Thank you, Richard. To my delight I've discovered you are correct. Believe it or not, I did read the manual to see if this was possible but the information was, shall we say, not prominently featured. "Buried" would be another way to put it. I do plan to discuss the pros and cons of using older lenses later in my review.

Mike, A response to your comment about “An f/2.8 lens is an f/2.8 lens…. Its max aperture doesn't change with sensor or film size.”
The thing is that the reviewer talks about “functional equivalents”, not aperture in absolute terms. Furthermore, it’s hilarious that you seem to accept the concept of a 50-135 “becoming” a 70-200. I mean, the focal length does not change with the sensor format either..
If you do want to compare systems you have to make sure that the (1) angle of view, (2) the light gathering area and the (3) depth of field are the same between the two systems otherwise the comparison is misleading and frankly worthless. A f2.8 lens on a 1.5x crop sensor actually corresponds to f4.2 in 35mm (same DOF, same light gathering)

This is the point when somebody will point out that an f4 70-200 FF will need twice the shutter speed to maintain the same exposure. Wrong again, because the full frame sensor gathers 2.25 times more light so you can crank up the ISO one step without an increase in noise.
The bottom line is: When comparing two different systems you CAN NOT just change one parameter and leave the others as is. It’s like saying that it’s better to transport goods with a car instead of a truck because the fuel consumption of the car is lower. You conveniently “forget” that the truck can carry a little bit more load….

This is the 4th or 5th time that TOP has caused me to grieve over the selling of my collection of Pentax K-lenses from 24 mm to 400 mm about 5 years ago because Pentax was slow to the digital game. Every time I remember this, it hurts a little more.

You have just made a very informative and unbiased review of Pentax K-7. I am planning to buy one for myself and I have bee reading reviews all over the internet to see if its worth the money. I am glad I found your site.

Gordon: for using M lenses, see page 294 in the manual. Without turning the "Using Aperture Ring" setting to "Permitted", you can't use non-A lenses — but if you change it from its default, you can.

Presumably this is the default so that it's obvious if there's a connection failure with a lens that _should_ communicate.

Well this was coming for a long time, hasn't it, and I'm glad it finally did.

Unfortunately Pentax has chosen to attach quite a price-tag to this, which I find rather surprising given their market position. In Germany a K7 will cost twice as much as a D5000, a 500D, an E-620, 40% more than a D90, roughly 25% more than an E-3, an Alpha 700, a 50D. A D300 - non "s" - will still be 30% more though than the Pentax. Just to put this inperspective moneywise. I think it'd better offer good reasons (over and above the weather sealing).

Two questions:
Gordon, you say
"I’ve always had a soft spot in my heart for Pentax cameras and lenses. "
but then
"... an experienced photographer with no particular bias for or against Pentax equipment ..."
I find soft spots to be the very essence of bias, no?

On a different note, Pentax gets a lot of mention on TOP in the context of primes, an all time Mike-favourite. Now, while I do not want to re-enact the great "why-use-primes-in-this-day-and-age" controversy, it has always escaped me why it has to be Pentax primes. I take it for granted, that primes should be reasonably fast, i.e. up to f/2 to have any raison d'être. A quick glance at a price-comparison website shows, that Pentax currently has 6 primes for sale (2 of them under 500€), while Canon offers 14, Nikon 12 (both have 6 below 500€) - all up to f/2. A more in-depth look at the available lens-reviews on Photozone, SLRGear and DPReview reveals that all makes have stars and losers. I could not find any reason for claims of extraordinary excellence re Pentax glass. Still, claimed it is - quite a Pentax community on photo.net e.g. - though it seems to me to be more of a soft spot matter. Maybe someone would try to explain/argue this point. Personally I think it would be best for a dedicated prime-user to buy any Canon, as one could use all makes of primes (even Pentax'), albeit with adapters, on it. Coming to think of it, the recent G(H)1 seems to offer similar flexibility.

I loved your comments and pictures. My first camera was a Miranda without an exposure meter and my second was a Spotmatic in 1965, I believe. I hope the Leica M9 inspires a move in the direction of smaller, lighter.

Just wanted to add how much I liked the shot of the lady with the umbrella. Very painterly, reminds me of Hopper. Well done. ch

You need an f/2 zoom to have an f/2.8 (35mm) DOF-wise...

"f/2.8 vs f/4" really shouldn't be thought of in terms of exposure OR depth of field. Mike didn't choose to specify it one way or the other. It's a physical property of the lens based on the diameter of the aperture and focal length. It doesn't directly concern either exposure or DOF - they are secondary effects. As Mike pointed out, the usage of the lens doesn't matter - it's always an f/2.8 lens.

I just wanted to confirm that Richard is absolutely correct that with the custom function enabled the use of manual K-mount (and adapted) lenses is possible. Also, in video mode they allow a more direct control as they let one control the aperture, and thus exposure (use the AE lock button then control aperture--the DOF/electronic preview collar [on the on/off switch] allows one to preview the exposure without recording).

Thanks for the review (segment).

Mike wrote: "An f/2.8 lens is an f/2.8 lens even if you have it mounted to a view camera or you're holding it in one hand and casting its image on your other hand. Its max aperture doesn't change with sensor or film size."

And neither does the focal length magically change, does it? But if one is to talk "equivalent" then focal length, max aperture and ISO must all be converted to conform to the light-gathering properties of the new sensor/film size.

For excruciating detail there's this article on equivalence, which could surely use a good editor.

"Although you can physically mount older manual focus K-mount lenses (often referred to as "K/M mount") onto the K-7 they won't communicate with the camera and the camera won't allow you to release the shutter, no matter what exposure mode you use. I know because I tried."

Well I just tested mine with a "M" 50/1.7 and it works fine - The pentax digital cameras don't read the mechanical aperture position, so you have to do a couple things to get this to work with K, M, or screwmount lenses...

1. In the custom menu, you need to set option #38, "Using Aperture Ring" to "permitted" from it's default "prohibited" (a crazy default but whatever).

2. The camera can't sense the aperture ring position, so you need to operate in "M"-manual exposure mode, but you can still use the built in metering - simply set the desired aperture on the ring, and then press the "green button" on the back of the camera - this will stop down the lens, meter, and set the shutter speed as needed for the aperture and ISO.

With "A" style electronic auto aperture lenses you can use them exactly like a modern AF lens - no need for the green button thing.

Mike - the rocking chair picture appears a little soft. I'm a K-7 owner and I know what they're capable of (on this monitor). My guess is that the image rendering is intentional? Gordon?

Great review so far and I'm looking forward to the second part. Thanks!!

"Now let me end by saying that all three pictures look fantastic, but in particular your picture of the lady under the umbrella is absolutely magnificent."

As I said in an email to a reader, that shot is "classic Gordon Lewis--clean but not oversimple, elegant, with 'found' abstract elements, unpretentious." The guy can take a picture.

Mike

"Furthermore, it’s hilarious that you seem to accept the concept of a 50-135 “becoming” a 70-200."

It is not hilarious, it's perfectly commonplace. It's done all the time all over the place by virtually everyone, and everyone knows perfectly well what is meant. And Gordon did not just say becomes, he said becomes the functional equivalent of.

I'm surprised you'd have the least bit of trouble with this locution or this concept at this late date in the digital revolution, or that anybody would.

Mike

In regards to the "obsequious ass-covering disclosure", I say keep it: not only do I find it reassuring, the particular details of disclosure (which vary a bit from article to article) are very interesting to me.

I wouldn't mind the disclosure being segregated into its own section, though. That would make it easier for folks like Jayson to skip it.

Robin Parmar : "And neither does the focal length magically change, does it? But if one is to talk "equivalent" then focal length, max aperture and ISO must all be converted to conform to the light-gathering properties of the new sensor/film size."

That not really true. The focal length has an equivalent because only one variable changes. So it's easy to say a 200mm is a 300 mm-equivalent.

This is NOT typically done with f-stop because the exposure doesn't change while the DOF does. So to say an f/2.8 lens is now an f/4 may lead you to think you've lost a stop of exposure when you haven't. It's only f/4 in terms of equivalent-DOF, not exposure. Since the lens is physically f/2.8, and your exposure will be based on that, it makes sense to ignore DOF for the purpose of spec'ing the lens.

I could see phrasing it in some way the includes the DOF shift, but it's kind of cumbersome. I suppose if enough people cared about crop sensor's effects on DOF, there would be some kind of standard.

As far as ISO goes, that has nothing to do with the format of the sensor. ISO is a standard that all sensors meet - some more precisely than others, but equivalent no matter the format.

Hedrik: "A quick glance at a price-comparison website shows, that Pentax currently has 6 primes for sale (2 of them under 500€), while Canon offers 14, Nikon 12 (both have 6 below 500€) - all up to f/2"

Yes by this measure Pentax doesn't do well.

If instead you say "I want a wide, a normal, and a short tele" and then look at what you can get, you find that Pentax has a good choice for all three of these, mostly small and many new designs. While (at least for crop cameras) C & N simply don't. Especially at the wide end.

I think that's what people mean about the primes thing. Certainly that's what I mean.

Some people also seem to hold a mythical belief that all pentax lenses since forever come equipped with magical fairy dust for your pictures, which is, of course, nonsense.

Nice review by the way! Looking forward to future parts.

"Mike - the rocking chair picture appears a little soft. I'm a K-7 owner and I know what they're capable of (on this monitor). My guess is that the image rendering is intentional? Gordon?"

I can assure you that the image I see on my monitor is razor sharp (except in areas that are outside the depth-of-field, of course). So is the print I made. It could be that the image lost some sharpness when it was downsized for the web. I'm tempted to re-size and re-sharpen it, but then I might get complaints from people claiming I'd overdone it. I guess I'll just have to resign myself to being unable to make everyone happy all the time. I'll include 100% crops for a few images in the future. Maybe that will help calm any concerns about sharpness. Then again, maybe not.

Ahh, guys, this DOF stuff :) If you take different sensor size cameras of the same brand (let's say a Nikon D700 vs. D90), and mount the exactly same lens to it, what happens? Only one thing. While the APS-C sensor size is smaller, some cropping occurs. The effect will be the same as you crop it down in Photoshop. This is why it is often called crop factor. The common misunderstooding (it works like a 1.5x longer lens) comes from this. Yes, an 50mm lens shows less on an APS-C camera, exactly the same field of view, what a 75mm lens does in full frame. But the lens is the same, no DOF, no f-stops, nothing else changes. (Maybe you get somewhat better results with some lenses because the sensor crops your edge effects like vignetting, CA or blurriness :D)

"It's one thing to read about "lack of dynamic range" in a lab report. It's another to see it in actual photographs. In my opinion the photo of the rocking chair on the porch is an example of a high contrast subject that displays adequate shadow detail in the photograph. I've used other cameras that definitely would have shown less. That said, it's something I'll be on the lookout for."

Gordon, I don't think your photo of the rocking chair is the type of image that would show the dynamic range issue.

Where I see the difference between the dynamic range of my Pentax K10D and my Nikon D300 is with high contrast image scenes where I underexpose to hold the highlight detail and then push the shadows and midtones to the correct exposure. When I expose and process images like this, the lower dynamic range camera shows a lot more noise in the shadows. For someone who doesn't expose and process their images this way, the dynamic range of the K7 shouldn't be an issue. For me, it's an issue.

JMR: There are some limitations in the lower models, particularly; the D40 and that level (I believe including the D60 and the four-digit models) won't auto-focus except with AF-S lenses, for example. But AF-D and straight AF lenses will mount and work, it's only auto-focus that's lacking (and of course manual focus lenses don't magically auto-focus either :-)). So if your salesman was warning you that not all lens functions were supported, he was right, but if he was saying you couldn't usefully take pictures with the lens, he was wrong. And these limitations occur only in the lower models.

I didn't get any kind of auto-exposure until I'd been photographing for 20 years, and no auto-focus for another 7 years after that, so I don't find these things to be issues, but YMMV.

All this controversy over the 50~135 / 70~200 comments are nothing new to Pen F users. We do the angle of view calculation in our heads any time we switch back and forth betwixt our full frame and half frame cameras. I don't know why it's so controversial.

"Now I am back with Pentax. A K-7 and 3 manual focus SMC K-mount primes (to Jeff Kott: of course you can use the old primes on the K-7)"

A case of mistaken identity - I never questioned that.

Hedrik: "A quick glance at a price-comparison website shows, that Pentax currently has 6 primes for sale"

DFA 50mm f2.8 Macro
DFA 100mm f2.8 Macro
FA 31mm f1.8 Ltd
FA 35mm f2 (NOT SURE ABOUT THIS ONE)
FA 43mm f1.9 Ltd
FA 50mm f1.4
FA 77mm f1.8 Ltd
DA 14mm f2.8
DA 15mm f4 Ltd
DA 21mm f3.2 Ltd
DA 35mm f2.8 Macro Ltd
DA 40mm f2.8 Ltd
DA 70mm f2.4
DA* 55mm f1.4
DA* 200mm f2.8
DA* 300mm f4

That makes 16.

Miklos Hajma wrote:
Ahh, guys, this DOF stuff :) If you take different sensor size cameras of the same brand (let's say a Nikon D700 vs. D90), and mount the exactly same lens to it, what happens?

Your example is good, but your conclusion is not. Remember that we talk about equivalents here. Lets say you want to take a picture of this scene with your 50mm lens, print it on A4 and give it to your uncle Robert.

First you take an image with the D700, lets say at f/2.8, 1/100s and ISO 400.
Then you take an image with the D90 that is the equivalent. What will the values be? First of all you have to step back because of the crop factor, and when doing so the DOF will increase so you have to set the lens to f/2 to compensate. You'll keep the shutterspeed otherwise the it will not be equivalent.
What will happen with ISO? Well you have to set it to ISO 200. Why is that? It's because a smaller sensor is noisier and for equivalence reasons you have to compemsate.

So, on the D700: f/2.8, 1/100s and ISO 400.
on the D90: f/2, 1/100s and ISO 200.

Same exposure, same shutter speed, same noise nevel, same DOF. This is equivalence.
(the image from the D700 will still look better because of the bigger sensor though)

Dear Robin,

"For excruciating detail there's this article on equivalence, which could surely use a good editor."

It's also in error in a number of places. In particular, the fascination with absolute aperture leads to some flat-out wrong statements.

Absolute aperture is of interest only to astronomers. It has NO useful for conventional photography. It does not correlate with anything--DOF, sharpness, sensitivity.

You've been led down the garden path, I'm afraid.

f/2.8 is f/2.8 no matter what the format. It has no "equivalence" when the format changes.

------


Dear Miklos,

No, DoF changes FOR A GIVEN PRINT SIZE (which is the way it's normally treated) with format size because the amount of magnification to achieve a standard print size changes, which means the acceptable circle of confusion changes.

pax / Ctein

Hi Gordon,

Applause for the wonderful people shots above, among the best I've seen from you. (I've been sporadically checking in on your blog ever since I read your Olympus review here.)

Maybe I missed it but I'm surprised no one has commented on the "K" image. I think it is a great photo and shows a great eye for graphic design. Very, very nice, Gordon.

Rob

• Robin Parmar wrote: And neither does the focal length magically change, does it? But if one is to talk "equivalent" then focal length, max aperture and ISO must all be converted to conform to the light-gathering properties of the new sensor/film size.

For excruciating detail there's this article on equivalence [link removed], which could surely use a good editor.

I haven't bothered to read the entire article as it is loooong*, but there's a rather important point here: Mr. James defines equivalence in a particular way; however, this is not the only way to define equivalence, and he even says this himself. Assuming that his way is the only way ("...must all be converted...," emphasis mine) is unnecessarily limiting. It can also cause confusion since, as Mike intimated, Mr. James' definition is less common than the one usually used (which has to do with maintaining the same perspective and subject framing, but nothing else). No harm in being precise, of course, but let's make sure we're all on the same page, first.

*Translation: I'm not sure if everything he writes is correct, and I don't want to take the time to pick it apart. Speaking of editing, it would be nice if he used more standard optics terminology at times; I'm not sure why he changes "entrance pupil" to "apparent aperture," for instance, as the original term doesn't really make it less readable, even for the uninitiated.

• Miklos Hajma wrote: But the lens is the same, no DOF, no f-stops, nothing else changes.

It's usually better to think of depth-of-field as an image property rather than a lens property. As you point out, just because the same lens is used on different formats doesn't mean the final image will be the same; if the final image isn't the same, then the DOF generally won't be, either. Bob Atkins has a decent primer on DOF in the digital age over at photo.net.

The rocking chair is on the soft side, but it's not too soft for me. Granted, it's not flickr-sharp, but it looks to me just barely sharp enough for the image size; also granted that acceptable sharpness has something to do with subject matter and taste.

There are definitely areas of more softness, though, and not necessarily where I would expect them to be this kind of composition.

Good grief, not the DoF thing again. Spare me.

Looking forward to part two Gordon! I'm right now going through photos from a 5 day vacation with a little Canon compact camera. This thing may be 12mp, but they are the nastiest little pixels I've ever seen. You can make a nice 2mp JPEG, perhaps a tiny print but that's it. Time for an SLR.

I agree, the umbrella shot is outstanding. What you said, Mike.

MODERATOR'S NOTE: Folks, it's really not fair to people who come to this post expecting to read about the Pentax K-7 to let the entire comment section of this review devolve into a rehash of the old dispute about d.o.f. We covered this in great detail not long ago.

Please see Ctein's post "Depth of Field Hell--The Sequel" on our site, at this URL:

http://theonlinephotographer.typepad.com/the_online_photographer/2009/06/depth-of-field-hellthe-sequel.html

or check Paul van Walree's excellent page on the subject:

http://toothwalker.org/optics/dof.html

for the facts. But no more here, please.

Thanks,

Mike

Mea culpa, Mike et al. Shouldn't have taken the DOF bait...

As for the K7, I'm also looking forward to the rest of the review. But what I really want to know is: if I buy a K7, will I be able to take pictures as well as Gordon?

Hendrick,

Your comparison is quite a bit unfair. The Pentax K-7 is Pentax's top of the line camera, the Canon and Nikon cameras you name are their introductory cameras. The K-m (and now, perhaps, K-x) is a much more suitable point of comparison for the cameras you cited. Conversely, the Nikon D300 or Canon 50D might be the proper comparisons to use for the K-7. Last I checked, which I believe was the K20d era, Pentax was offering more features on their top model than the competition included in their comparable prosumer models, but this may no longer be the case.

To your point about primes, when I was shooting Pentax, I was doing so because they had a full lineup of made-for-digital primes, meaning it was possible for me to shoot wide angle primes, normal primes, and telephoto primes. With Canon or Nikon, I needed a made-for-digital wideangle zoom and some wide and normal-to-longish (in full frame terms) primes to cover my bases. That's still the case today. Plus, Pentax's DA Limiteds are tiny and sharp, easy to carry around, fun to shoot with, and all deliver magnificent results.

In the end I ended up with a D700 and a set of primes in my favorite focal lengths, and I'm happier for it, but I do miss those little gems.

I meant to mention another of my favorite things about Pentax: the President of Pentax America, Ned Bunnell, is an actual photographer that actually uses the cameras and lenses and knows what people want. He has a nice Pentax blog and is reportedly easily approached and eager to hear what his customers want (I can't confirm, I never had cause to reach out). In no way would I characterize Canon, Nikon, or Sony's leadership in that way.

I love my Pentax dslr but I wonder if they are not taking this saturated colour thing a tad too far:
K-x available in 20 body colours and 5 grip colours

Gordon, sorry - my comment on "soft" was not intended as negative. The pastel areas (cushions and brick wall)look good to me as they are rendered. The back chair cushion is certainly sharp. But, I'll bet you were shootin' pretty wide open (2.8?). Thanks again for a great review, and a wonderful gallery. I work mostly with portraits, and your art is truly elegant.

This would probably be the first DSLR I'd try (maybe with a 21mm pancake, though it's a bit wide for me) if I were buying today. The amount of useful stuff packed into that size is great. (Mike, I originally missed your update of an older post here telling us that Pentax US had confirmed the K7 to be weather sealed, a claim had been debated.) Nice review so far. Thanks.

Not only is Ned Bunnell the President of Pentax America, but he blogs about his Leicas.
The gist of which is they are good for some people to do some things, but that Pentax couldn't make any money in that market.

Now if only customers could be as open minded.

It's great to see Pentax now have a top spec body worthy of the awesome DA/FA Limited glass.

Thanks for the review - fantastic photos. I really like the shot of the lady and the umbrella. Fantastic.

Looking forward to the rest of the review. I currently use a Nikon F6, but my girlfriend has a K10D - and it's a fantastic camera (I can't understand why anyone bought a D80/D200/30D at the time!)

@ hopey
I wrote* "I take it for granted, that primes should be reasonably fast, i.e. up to f/2 to have any raison d'être." and only then, that Pentax currently is selling six of these. And that's exactly the number you come up with. Now, you may argue that premise, but I did not really want to get into the prime vs zoom discussion all over again. To me it definitely is another "soft spot" issue or as a co-poster put it, the belief in angel dust.

@ Will
I actually gave* the price-relation for the Nikon D300 or Canon 50D you mention, plus many more.

I wonder, why would a Canikon "made for full-frame film" prime not do on an APS-C camera, why would one need "made-for-digital"? Truly curious.

*Angel-dust sure makes for a lot of selective perception, I say ...

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