[Durf]

I understand that it may be a calibration problem, however, in my days with such a lens you almost would forget focusing a f/8, just set hyperfocal on the barrell and have everything sharp.
I have already returned one, I feel embarrassed to return this one too...
Can't really say it sucks of course, I'm saying that the triplets are better...

That's some seriously bad luck if you got 2 bad copies. Mine is outstanding and renders detail amazingly. I'm 110% happy with the copy I got.
Image Samples: PENTAX-D FA 21mm f/2.4 Limited Image Samples | Flickr

[mikesbike]

There are some aspects I notice between the two examples given that to me can account for the different outcome other than lens quality. Both lenses are capable of very high quality imaging. First aspect is exposure, then is contrast. Time of day can be huge in bringing about differences in outcome. The sky and its reflective nature are very different here, perhaps with some haze as well. The framing included a difference in content, being of course a considerable difference between 31mm and 21mm. With more foreground elements in the 21mm shot, the camera's meter of course took these into its reading for exposure, which could cause some overexposure of the distant central part of the frame which is of a much brighter nature. Big Mack does a great job showing how a bit of exposure comp is needed to correct what the camera's meter cannot know. This also improves contrast too. This makes a difference in perceived sharpness as well. But upon examining actual detail, the two lenses appear to be very close in performance. Most of these foreground elements are missing from the 31mm shot, and also a better balanced lighting characteristic due to the time of day and changes in the sky, so the camera's meter was able to deliver a fine result on its own.

One odd thing is, the distant parts of the scene appear closer in the 21mm shot compared to the same parts shown in the 31mm shot. The reverse of what would be expected. This suggests the two images were shot from a different location in addition to being under very different lighting.

[Gian]

That's some seriously bad luck if you got 2 bad copies. Mine is outstanding and renders detail amazingly. I'm 110% happy with the copy I got.
Image Samples: PENTAX-D FA 21mm f/2.4 Limited Image Samples | Flickr

your samples are amazing..

[yucatanPentax]

One odd thing is, the distant parts of the scene appear closer in the 21mm shot compared to the same parts shown in the 31mm shot. The reverse of what would be expected. This suggests the two images were shot from a different location in addition to being under very different lighting.

I noticed that too -- the 31mm shot shows a wider range of the mountains than the 21mm shot, so it was in a different location and included a different foreground. Not on itself a part of the proof of the image (especially since part of the complaint seems to come from concern over muddiness in the browns on the 21mm).

It seems there may have been a fair amount of distance between the two locations.

[house]

The time of day and exact location are irrelevant. You don't need that level of precision to see that the dfa21 shot looks odd and smeary. We do need full resolution images to understand what is going on.

[garywakeling]

Hi Gian
I have noticed that for such a wide lens the 21mm has a very shallow depth of field, I have the older FA 20mm as well as the FA* 24mm and I agree, when set at f8 you really could basically just point the lens in the direction of the subject and almost everything in the frame would be in focus using the traditional hyperfocal distance. This lens behaves in a completely different way, it has quite narrow depth of field to help isolate your subject, this is one of the strengths I have enjoyed using the lens. I find it has really helped isolate the subject with plenty of bokeh around it. Perhaps trying some RAW exposures rather than the JPEGs might help. The close up ability is great as well, I'm sure if you get out and use the lens daily you will be bringing home shots that you will be proud of in no time. The recent APSC Limited lenses have done little to impress me other than to be small and compact, this new 21mm does honour the spirit of the original 31,43 and 77mm lenses in delivering unique renderings rather than lines per millimetre on a test target. Here is a link to some photos I have taken this month with the lens in the single in challenge
HD PENTAX-D FA 1:2.4 21mm ED Limited DC WR | Flickr good luck and I hope the lens grows on you

[micaz49]

One of the first user tests (in French but easily translated into English by deepl.com) was published by PentaxKlub ([Test] HD Pentax D FA 21 mm f/2.4 ED Limited DC WR)

[redpit]

I don't understand what I see in the comparison. I can't understand why the DFA 21 was so overexposed either. Something is wrong and to tell you the truth these are no comparison pictures. The FA 31 ltd frame is wider than the DFA 21 ltd! It would be very helpful for you too if you took both of your lenses and try them on exactly the same spot at the same time and with the same settings and finally focused at the same exact spot. No cropping either and please show us the full resolution Jpegs.

PS: After the exposure correction that @BigMackCam did the house and the rest details on the cape in the middle of the frame seem quite better than on the FA 31... Still I don't get how the wider lens gave a more tele result

[Ole]

One could suspect that the lens doesn't stop down. It is a KAF4 lens with electronic aperture contrary to your other limited lenses.

Have you checked if the fault is with the camera, for example with the power contacts linking camera and lens?

Set the aperture to e.g. 11 and verify that the optical preview button actually stops the lens down. Also verify that the aparture blades closes down instantly.

[jersey]

Try to focus manually on the pines and check then. If you are still not happy, but what you focused on is in focus then I would not overthink it, return lens and forget about it. Sometimes lenses just not work for certain photographers and their style of doing things.

[Wheatfield]

here they are, first one is 21, second one 31

Your exposure looks significantly different.

[Rondec]

One could suspect that the lens doesn't stop down. It is a KAF4 lens with electronic aperture contrary to your other limited lenses.

Have you checked if the fault is with the camera, for example with the power contacts linking camera and lens?

Set the aperture to e.g. 11 and verify that the optical preview button actually stops the lens down. Also verify that the aparture blades closes down instantly.

I wonder if you are right. Previous lenses stay stopped down without camera input, while KAF4 lenses shoot wide open without input. If the camera thinks it is shooting at f8 and the lens is actually at f2.4 that will give this sort of effect. Maybe simply updating firmware on the K-1 might help out?

[house]

I wonder if you are right. Previous lenses stay stopped down without camera input, while KAF4 lenses shoot wide open without input. If the camera thinks it is shooting at f8 and the lens is actually at f2.4 that will give this sort of effect. Maybe simply updating firmware on the K-1 might help out?

Sounds reasonable but you'd expect a much more over exposed image if it uses f2.4 instead of f8.

[Rondec]

Sounds reasonable but you'd expect a much more over exposed image if it uses f2.4 instead of f8.

Maybe. I'm just thinking of the reverse of the aperture block issue seen on K-30 cameras.

[BigMackCam]

I don't think a stuck or faulty diaphragm or diaphragm control are the issue here, though I guess it's possible. Assuming the exposure was set by one of the semi- or full-auto modes, the reason for the higher exposure in the D FA21 shot is probably metering, and easily explained if we knew all the variables.

I'm hoping @Gian will try a side-by-side, tripod-mounted test of both the D FA21 and FA31 in the same session, using Live View to autofocus on the same central subject and shooting with a range of apertures from f/2.4 to f/16. I'd suggest TAv mode, with the same shutter speed for all shots - say, 1/250s or higher to rule out shutter and/or mirror shock...