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02-13-2018, 08:14 AM   #1
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Is my FA35 2.0 as sharp as it should?

Just bought a FA35 2.0 after selling my FA31 1.8 Limited. Now I'm not really sure about its results. While I really like the way it renders, I'm not 100% sure about the sharpness of my copy. Would you help me judge my copy in terms of sharpness? Maybe some of you also have a FA35 2.0 and are able to say a few words about the performance of my copy.

Took some pictures from f2.0 - f3.5 etc. to see if it's spot on and sharp. Focus was on the right eye (from my perspective).
Would you say it's okay?

Uploaded the pics on my dropbox:

Dropbox - FA35 2.0

Would be very happy if you could help me judge my copy. I appreciate your support.

Pictures taken in RAW, just exported from C1 using the JPEG-Format

02-13-2018, 08:18 AM - 1 Like   #2
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Can't view from my phone right now.

However these questions are likely to come up: Did you auto focus, manual focus, liveview or use the viewfinder?
02-13-2018, 09:12 AM - 1 Like   #3
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It is FA 35mm f2. DA 35mm f2.4 is another lens (almost same optical design, but different lens)
Those photos could be sharper, but most lenses are not super sharp wide open.
Maybe you just need focus adjustment. There are many threads about Focus adjust function in DSLRs. you can print out focus chart and use other tools. At f2 even a couple mm misfocusing can make the whole photo seem blurry. I would start with this. Make sure you give the lens enough time to focus and the SR to activate (the above sample photos seem to be done in slightly dark location)

And while the FA 35mm is pretty sharp, it is possible the FA 31mm spoiled you. FA 31mm is legendary lens and FA 35mm f2 is cheaper. It is not terrible, but it is not on the same level

Btw you can check reviews and sample photos here (note that some of the samples have digital sharpening added):
https://www.pentaxforums.com/lensreviews/SMC-Pentax-FA-35mm-F2-Lens.html
https://www.pentaxforums.com/forums/samplesearch.php



Last edited by Na Horuk; 02-13-2018 at 09:18 AM.
02-13-2018, 09:20 AM - 1 Like   #4
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Past tests of the fa 31 and fa 35 from the past I have read showed better edge to edge sharpness wide open on the fa 35 than 31 with higher center sharpness on the fa 31.

Neither lens should lack sharpness.

02-13-2018, 09:44 AM - 1 Like   #5
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The lens should be quite sharp, but I'd use a different subject for evaluation, so that you can control the variables better (i.e. tripod, fixed distance, smaller subject). As suggested by others, I'd also check for front/back focus if you're focusing through the viewfinder.

Also keep in mind that the FA 31mm is a much more expensive lens, so you should expect to see some hint of this in the relative image quality.

Adam
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02-13-2018, 10:00 AM   #6
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Thank you all for your helpful and elaborated feedback! I really appreciate it!

As you've assumed correctly I haven't applied "scientific" standards, just shot without using a tripod. However, sometimes this also works with other lenses . I hardly ever miss a shot for example using my FA43 1.9
But you're right, to be sure I should use a tripod, the live view etc. I will get back with some more shots when this is done. Unfortunately my K-1 isn't here again so I could only use my K-30 to do some testing. Does this make sense? But center sharpness of the lens should also be testable when using a APS-C cam, right?

Actually some of my lenses are softer or lack contrast wide open. But stoping them down (often by just one stop) improves the image quality and sharpness significantly. My copy of the FA35 however needs to be stopped down quite a few stops to get really sharp in the center (at least judging from the view shots shown here in this thread). That's what really surprised me.

@Adam: Thanks for your comment as well! Yes, I shouldn't expect same image quality from the FA35 in comparison to the FA31. But at least, I wanna get as close as possible .

The reason I sold the FA31 wasn't it's image quality. I really liked it a lot (Lausbub ? Scallywag | the-living-years | Flickr).

But I hardly used it on APS-C. And I found out that when traveling (that's where 95% of my photos are made) I prefer to leave it at home since I'm afraid of damaging it on the journey... So the FA35 came in handy due to its lower price tag .
02-13-2018, 10:42 AM - 2 Likes   #7
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QuoteOriginally posted by zeitlos Quote
As you've assumed correctly I haven't applied "scientific" standards, just shot without using a tripod. However, sometimes this also works with other lenses . I hardly ever miss a shot for example using my FA43 1.9
But you're right, to be sure I should use a tripod, the live view etc. I will get back with some more shots when this is done. Unfortunately my K-1 isn't here again so I could only use my K-30 to do some testing. Does this make sense? But center sharpness of the lens should also be testable when using a APS-C cam, right?
Your lens is plenty sharp for the portions of the frames that are in-focus.* This is readily apparent.

Conventional wisdom for lens sharpness testing include removing or minimizing all other factors that might contribute to softness. In practice with either of your cameras that means:
  • Use of a high-detail, high contrast, flat target parallel to the focal plane
  • On tripod
  • Moderate distance from target (about 20x the focal length)
  • SR disabled
  • Time delay and/or remote shutter release, mirror up, electronic shutter or whatever allows minimization of user and mirror-induced vibration. With my K-3, I use a wired remote and 2s delay or mirror-up if I am feeling particularly fussy.
  • Manual focus using magnified live view. I prefer doing this with focus peaking turned off. Switching out of live view for the actual exposure might be wise, depending on camera.
Your K-30 should work fine, though the K-1 has more ways to avoid camera vibration.


Steve

* There is a mix of front/back focus

Last edited by stevebrot; 02-13-2018 at 11:59 AM.
02-13-2018, 10:51 AM - 1 Like   #8
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Just get an FA31 that already has some exterior damage, and then don’t worry about it. Use it, scratch it up some more, enjoy it.

02-13-2018, 10:59 AM - 2 Likes   #9
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The parts that are in focus of your test shots look pretty sharp to me. I'd like to see comparisons of the same subjects with your 31mm.
02-13-2018, 11:57 AM   #10
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To me it looks like it is front focused slightly and something that should be easily correctable using the AF fine adjustment for that lens. I would suggest getting out a high detail image, putting it on a wall, and have the camera at a fairly shallow angle to it at a reasonable distance (several feet). Put the camera on a tripod and then get the auto-focus adjusted for that lens.

I have the 35mm f/2.4 and when I first got that lens I thought I had a very bad copy as the subject was very out of focus unless I shot in live view. Turned out it was back focused a lot so after a bunch of photos of my kids' world map, centered on and focus point set to Zambia, on the wall and adjustments it is now performing as expected but the auto focus fine adjustment setting for that lens is at +8. None of my other auto-focus lenses have had that problem and when shooting in live view it didn't have that problem.
02-13-2018, 12:19 PM   #11
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I have the FA35 on my K-1 and its probably my most used lens. I would expect it to be sharper than in those images (mine is) - although there a few things to check first:
* The obvious - use a sturdy tripod and remote or self timer
* Try focusing in LV (for OVF I needed to fine tune the focus on FA35 to get the best out of it)
* Turn ESC (electronic shutter) on in LV and try that too as, due to its light weight, I have seen effects of K-1 shutter shock (1/90 - 1/250 shutter speed range) which might explain some of this.

Otherwise is should be a great lens. Its so easy to carry around and very good performer.
02-13-2018, 01:13 PM - 1 Like   #12
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I agree with stillshot2. You say you focused on the eye. In the second example among those presented, I find her eye to be quite sharp. And these are not posted at full size resolution. At f/2 there will be a shallow DOF, so not much of the scene will be in sharp focus. Of course, both the FA 35mm f/2 and the 31mm f/1.8 Limited, although capable of such sharp results wide open (unusual, especially in a fast lens!), both lenses are still not at their very best wide open. I don't see anything wrong based on what you show here. It is certainly not the way to do a definitive lens test, but as a quick check it passes the test easily.
02-13-2018, 01:26 PM - 1 Like   #13
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Looks like missed focus for the most part. Try live view first - it's the easy test. Try a tripod and 2 second self timer to get pseudo mirror lock up benefits. Also shoot it on the K-1; the K-30 focus system is pretty old and cranky and the fine focus adjustment will vary by body (not model per say) so you may find if you have a focus issue on the K-30 you may not have one on the K-1 or it might be in the opposite direction even!
02-13-2018, 02:22 PM   #14
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Could it be yet sharper, probably, but for a grab shot in dimmer lighting, I'd say quite decent. What shutter speed did you get? With a live subject especially, this is important.
02-13-2018, 05:20 PM   #15
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QuoteOriginally posted by zeitlos Quote
Unfortunately my K-1 isn't here again so I could only use my K-30 to do some testing. Does this make sense? But center sharpness of the lens should also be testable when using a APS-C cam, right?
Yes, APSC cameras have high resolution and will give you at least some feedback for image sharpness (just not in FF corners). However, AF fine adjustment can be different from camera to camera. AF adjustment is made to fix the difference in tolerances between lens and camera. Usually you don't need it, but sometimes you might. A lens can front focus on one camera, but its fine on another camera. So for AF adjustments you have to do it on each camera
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