[pendennis]

On a more serious note, I do tend to notice some difference in general between crop lenses designed for digital and FF lenses designed for film. You tend to get a snap and saturation with the newer lenses, but a busier look in the near-OOF areas. Especially for landscapes and portraits, I tend to prefer the older, softer look that strikes me as more realistic. This became especially apparent with the DA 50 compared to the older 50s.

Not sure why that would work that way, other than differences in the coatings. One thing I really appreciate with the FF lenses is that they tend to render sharpness similarly on crop across the frame (even though they are likely to have heavier CA on the edges) whereas modern lenses often show considerable sharpness degradation toward the edges compared to the ultra-sharp center. This center-corner sharpness difference is especially apparent in comparing the FA 35 to the DA 35 on crop.

The sensors for digital aren't the same as the grains for film; the light isn't recorded the same way. Lenses for film cameras are designed to maximize the resolution for that medium. Newer lenses are designs which maximize the light gathering for a sensor. I don't think anyone would call Leitz's lenses "soft" in any respect, nor lenses like the Nikkor 50mm f1.8, or the Pentax SMC 50mm f2. In an age where lenses were designed using slide rules and paper, the lenses are superbly sharp and color balanced; and modern CAD/CAM processes make the design and engineering stage much less subject to calculation errors. The lens coatings are another story, and I agree with you that the modern coating are probably superior for digital imaging.

I still get great images using a manual focus Nikkor 24mm f2.8, and my Pentax SMC A 50mm f1.7. I don't often go "retro", using lenses designed for digital on my film cameras, but I can always correct most anything when I scan and edit.

[audiobomber]

Not sure why that would work that way, other than differences in the coatings. One thing I really appreciate with the FF lenses is that they tend to render sharpness similarly on crop across the frame (even though they are likely to have heavier CA on the edges) whereas modern lenses often show considerable sharpness degradation toward the edges compared to the ultra-sharp center. This center-corner sharpness difference is especially apparent in comparing the FA 35 to the DA 35 on crop.

Doesn't the FA 35 use glass elements and the DA 35 f2.4 use plastic? I assumed that was the reason for the difference in FF performance.

[Rondec]

The biggest problem with using full frame lenses on crop cameras is that many of them feel "too long." The FA 31 is a very nice wide angle on full frame, but a very expensive "normal" lens on crop. It is still a nice lens and has less vignetting wide open on a crop camera, but otherwise not a big difference. But if you are interested in landscape, DA 15 or 21 would probably be better choices for a crop camera.

The whole equivalence thing to me is a bit of a red herring. If I take the DA *55 on a K3 camera and a FA 85 on a K-1 and shoot the 55 at f1.4 and the 85 at f2, I'm going to get pretty similar pictures. That's all that equivalence really says. Now, in point of fact, the FA 85 is probably going to look a little better at f2 than the DA *55 looks at f1.4 (the 55 is a little weak wide open). The DA *55 could be shot on both cameras and if you do that, you are just going to get different images -- the ones on the K-1 being sort of a long normal and the ones on your crop being a short telephoto appearance. That certainly doesn't mean you shouldn't shoot the lens on one or the other, but I would say that if you like the framing you get with your 55 on a crop camera, then you probably should look for an 85mm lens for your full frame camera. Continuing to use the 55 will seem short.

In the end, whatever format you use, you should find lenses that make you happy and don't worry about equivalence. It is more for people to argue about on the internet (mostly, in my experience, to prove that full frame cameras and lenses are better).

[RobA_Oz]

Regardless of equivalence theories and smacking down Mr Northrup, one advantage of using 35FF lenses on APS-C bodies is that, with the later Pentax DSLRs, some of that otherwise wasted light in the bigger image circle can actually be put to use with sensor shift, both for vibration reduction and for image shift, including in-camera correction for converging verticals. Of course, you don't get that in other systems.

[BigMackCam]

Doesn't the FA 35 use glass elements and the DA 35 f2.4 use plastic? I assumed that was the reason for the difference in FF performance.

I don't know if the DA35 f/2.4 has any poly-carbonate elements - it wouldn't surprise me if that's the case, though. A few modern Pentax lenses (and plenty of third party models) have poly-carbonate bonded aspheric elements.

That said, the resolution performance from this lens will be exactly the same on sensors of different formats that are otherwise equal (i.e. same pixel density, same AA filtering etc.), if you limit comparison to the relevant area of the image circle, and view that area at the same physical dimensions.

To prove that in a non-technical way, we can simply use a lens on the K-1 in both full frame and crop modes. The sensor remains the same - we're just using a smaller part of it by cropping. The lens doesn't perform any differently as a result of the crop.

[audiobomber]

To prove that in a non-technical way, we can simply use a lens on the K-1 in both full frame and crop modes. The sensor remains the same - we're just using a smaller part of it by cropping. The lens doesn't perform any differently as a result of the crop.

Sure, but the loss in resolution from FF to APS-C occurs when you take that crop and magnify it to the same screen size or print size as the uncropped image. Now you have a smaller angle of capture, with less DR, more noise, lower resolution and more visible CA.

[UncleVanya]

Sure, but the loss in resolution from FF to APS-C occurs when you take that crop and magnify it to the same screen size or print size as the uncropped image. Now you have a smaller angle of capture, with less DR, more noise, lower resolution and more visible CA.

Only if you use the K-1 as your source. If you start with the K-3 or K-3ii and you crop the FF to a similar view as what you had in the K-3 and then resize both back to the full uncropped size the K-3 will have more resolution. It is more complicated than x is better than y - but it's also simple - shoot with what you have and enjoy it.

[BigMackCam]

Sure, but the loss in resolution from FF to APS-C occurs when you take that crop and magnify it to the same screen size or print size as the uncropped image. Now you have a smaller angle of capture, with less DR, more noise, lower resolution and more visible CA.

I see where you're coming from... My point is, that's not due to the lens performing any differently on one sensor than the other. It's simply a physical scaling issue. If the images are viewed / printed in proportion to the crop factor, there will be no difference. The lens isn't part of the equation, agreed?

[normhead]

I see where you're coming from... My point is, that's not due to the lens performing any differently on one sensor than the other. It's simply a physical scaling issue. If the images are viewed / printed in proportion to the crop factor, there will be no difference. The lens isn't part of the equation, agreed?

Most full frame sensors don't have the same pixel density as crop sensors, so it's pretty much a moot point.

IN the area of the crop, a K-3 will give you 2700 lw/ph, a K-1 will give you maybe 2100 lw/ph. The APs-c gives you more resolution in the area of the crop. If you include area outside the crop, the K-1 will give you more resolution, but probably not on your subject, using the same lens. At least of for the here and now with the pixels densities being so different.

[shardulm]

That video is hogwash
Lose depth of field ? Oh lordy, does the man not understand if you use an aps-c camera and the same focal length, you will stand further away from your subject, and it is this that increases DOF.

This.. exactly this.. and over and over.. why don't people get this simple thing. And then they will talk better bokeh on FF and not so much on APS-C. Ignorance is bliss.. but this is not one of them.

[normhead]

This.. exactly this.. and over and over.. why don't people get this simple thing. And then they will talk better bokeh on FF and not so much on APS-C. Ignorance is bliss.. but this is not one of them.

As stated, his knowledge of gear is impressive, his theoretical knowledge of photography is disturbing. On year at Ryerson or Rochester would have cured him of this kind of statement. He truly is living in ignorance.

[audiobomber]

Only if you use the K-1 as your source. If you start with the K-3 or K-3ii and you crop the FF to a similar view as what you had in the K-3 and then resize both back to the full uncropped size the K-3 will have more resolution.

Agreed!

I see where you're coming from... My point is, that's not due to the lens performing any differently on one sensor than the other. It's simply a physical scaling issue. If the images are viewed / printed in proportion to the crop factor, there will be no difference. The lens isn't part of the equation, agreed?

Agreed!

IN the area of the crop, a K-3 will give you 2700 lw/ph, a K-1 will give you maybe 2100 lw/ph. The APs-c gives you more resolution in the area of the crop. If you include area outside the crop, the K-1 will give you more resolution, but probably not on your subject, using the same lens. At least of for the here and now with the pixels densities being so different.

Agreed!

[BigMackCam]

Most full frame sensors don't have the same pixel density as crop sensors, so it's pretty much a moot point.

IN the area of the crop, a K-3 will give you 2700 lw/ph, a K-1 will give you maybe 2100 lw/ph. The APs-c gives you more resolution in the area of the crop. If you include area outside the crop, the K-1 will give you more resolution, but probably not on your subject, using the same lens. At least of for the here and now with the pixels densities being so different.

Right. This goes back to my earlier point - that sensors with similar pixel density, regardless of format, will give very similar results for the same lens. The sensors in the K-1 and - for example - the K-5IIs have very similar pixel densities (I think?), so the same lens on both cameras should give very similar results, if the K-1 image is reproduced such that the APS-C crop portion is the same physical size as the K-5IIs image.

Frankly, I think all of this is essentially moot. Full frame lenses work great on APS-C cameras. Differences due to sensor pixel density - whilst apparent when pixel peeping - can and should be ignored. If the field of view is appropriate and the lens renders nicely, that's all the reasons we need to justify its use on crop.

A related side note: As I recall, the FA77 Limited beat (only just) the DA70 Limited when the two were tested side by side on an APS-C body, right here on these very forums

[monochrome]

I’ve always thought that last paragraph says more about the DA70 than it does about the FA77.

[normhead]

I’ve always thought that last paragraph says more about the DA70 than it does about the FA77.

MY suspicion is the DA 70 while test chart sharp doesn't have the same $D portrait spec the 77 does. But I've never had a copy of either lens. My memory is guys wo appreciate the 70, don't appreciate the 77, and vice versa. Apparently there's two kind of people in this world to go along with the two kins who either don't like either or like them both.

Did i leave anyone out?