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06-29-2014, 12:01 PM   #31
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QuoteOriginally posted by zeitlos Quote
@Na Horuk: Thank you very much for your comment and all the useful tips! I will try to do your test as soon as possible. This is really valuable information!
I highly appreciate it!

@Nicolas06: to a certain extent I see your point. However, in a test like this it should be able to show good results (in particular when a zoom lens like the Tamron 28-75 performs better in the same situation).
This is only valid at same apperture because the deph of fied in insufficiant, with exactly same shooting distance, focal lens and focus distance. On the first set of shoots, the tamron focus for the picture @f./2.8 is not on same distance as of the 31. On the 31 shoot @f/2.8, the hair in back of the image are more in focus, while it is not the case for the tamron.

On the second set of shoots, the details are more magnified for the FA31 shoot. The shoot hasn't been set as same distance of deph of field is even more thin...


I think your FA31 is not a good performer, I agree with you on that. But the way you do your tests doesn't help. use the methodology explain just before for better results !

06-29-2014, 02:30 PM - 1 Like   #32
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I'm not an expert, but I'd never use a 3d subject to test a lens. It's hard enough to get exactly perpendicular to a flat object, but at least when you do you don't have DOF issues, except for focus field curvature (but that's another story.)
06-29-2014, 09:28 PM   #33
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oh, I love eye-af on my A7

Difficult to say from that smaller crop whether you missed the focus or problem with your FA31 because IMO if you had missed the focus, at least some part of hairs in front or behind the eye would have been in focus but none seems to be in sharp focus. Try shooting a focus chart or a scale and maybe post slightly larger images here.
06-29-2014, 09:47 PM - 1 Like   #34
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have you tried AF adjust? It looks like it is either your technique or the AF needs to be adjusted.

These have been shot RAW and PP'd but mine is great right from 1.8 and very very sharp by 2.8

EDIT: just saw your liveview shots and they dont look much better hopefully the copy is not bad. but frankly if it is I would return it to the service center that supposedly fixed it for you...but still try an af adjust in the body if you havent. the 31 should be pretty damn sharp

f1.8 (handheld, moving taxi)


f6.3


06-29-2014, 10:51 PM   #35
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So much of this is anecdotal, and it's hard to really say for certain with these sorts of tests. I got your message and my saga is actually continuing. CRIS has had my effing lens since spring - it made one trip back to me and I returned it (they offered that or my money back). At any rate, it's been there on a "Parts Hold" for three weeks now. They did find something wrong but I've not pursued it much and am just waiting patiently.
The 1st photo from Deimos above is one that convinced me to pursue fixing mine at all, simply because I've plenty of shots of my lady handheld like that at wide apertures and they were never close to the kind of detail resolve his photo shows. So..... I bought another used one. Now THIS one peforms how I'd expect... and I expect the other to perform as well or better .... once I finally get it back... and sell it.
06-30-2014, 12:51 AM   #36
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Thank you all for your thoughts on my little issue here! I appreciate it!

I'm just in a hurry, going to work soon, so just some more testing I did tomorrow, now using a test chart.

You can download the JPEG-Original (shot in RAW, exported from Aperture into JPEG) right here if you want. These are not crops.

Pic-Upload.de - IMGP0658.jpg
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Pic-Upload.de - IMGP0665.jpg


P.S. Even tough you don't like my original way of testing very much () I was curious to see what happens when I do the same test from my tripod again, but now focusing manually using the live view and the magnification mode... the results equal a lot those pictures I shot yesterday using the AF. f1.8 seems kind of soft, f2 looks better I'd say. At least it's way better than the once I got when I did the test for the first time... Keep in mind, these are no crops this time.

Pic-Upload.de - IMGP0649.jpg
Pic-Upload.de - IMGP0650.jpg
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Pic-Upload.de - IMGP0653.jpg
Pic-Upload.de - IMGP0654.jpg
Pic-Upload.de - IMGP0655.jpg
Pic-Upload.de - IMGP0656.jpg

By clicking on the pictures you can enlarge them.
06-30-2014, 01:16 AM   #37
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I don't think the lens is the problem - your camera body, particularly the AF adjustment for this particular lens is incorrect. I would suggest an AF adjustment of +4 would be a good place to start.

QuoteOriginally posted by zeitlos Quote
I'm aware of the fact the the FAs aren't famous for being the sharpest lenses on earth
I have been using pentax FA lenses for years and the FA limited lenses when stopped down can easily give current Leica lenses a run for their money ( I also use the Leica M8, M9, Monochrom and the Leica S2
so I know what I'm talking about)
QuoteOriginally posted by zeitlos Quote
I'd say, at f4 it starts to get sharp.
My FA31mm f/1.8 has no centering defects, and so far on my Pentax K5IIs it has needed no AF adjustment whatsoever. In terms of sharpness it is just getting started at f/1.8, It is perfectly usable at that aperture and at f4 on the Pentax K5IIs it is an extremely sharp lens.



Pentax K5IIs with the FA31mm at f/1.8 - default sharpening in LR5.


Last edited by Digitalis; 06-30-2014 at 01:31 AM.
07-02-2014, 06:54 AM   #38
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@Digitalis: Thanks for your reply!

I've now sent in both my K-5IIs and my K-30 to have it's AF-Modul adjusted. As some of you hinted, I'm also pretty sure that (at least as far as its performance together with my K-5IIs is concerned) there's something wrong with the cameras. Not sure if's theres a FF/BF at my K-30 (see the pictures I've just posted in my previous posting), but I will tell you as soon as I got it all back.
07-02-2014, 07:09 PM   #39
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A few captions on the example photos would make life so much easier.

As with several other interested commentators, I think there is some missed focus at work here. I have to confess to not having waded through the full thread, but here are my musings even though:
  • Do all tests on tripod. I believe that is already your practice.
  • Confirm the lens is free of gunge and fungus inside and out
  • Forget about AF. Do your evaluations using manual focus and focus peaking in magnified Live View on your K-30.
  • Make things easy on yourself and limit yourself to a non-moving stationary subject
  • Make things double easy and use a flat, high contrast, high detail target (e.g. newspaper classified ads) as the subject
The intent of the above is to:
  • Test the optics and not contamination
  • Test only the lens and not the AF system
  • Test only the lens and not the ability of the model or photographer to hold still
  • Provide a subject where DOF is not part of the equation
  • Provide conditions where the scales are tipped in favor of the photographer being able to consistently attain focus


Steve
07-02-2014, 10:54 PM   #40
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QuoteOriginally posted by zeitlos Quote
@Digitalis: Thanks for your reply!

I've now sent in both my K-5IIs and my K-30 to have it's AF-Modul adjusted. As some of you hinted, I'm also pretty sure that (at least as far as its performance together with my K-5IIs is concerned) there's something wrong with the cameras. Not sure if's theres a FF/BF at my K-30 (see the pictures I've just posted in my previous posting), but I will tell you as soon as I got it all back.
- First point: your shoots with tripod are better.
- Second point: shooting the test chart, one can see the focus is done on the +1 or +0.5 instead of 0. You can already see the thin aspect of the deph of field. And if not perfect, the +1 is already ok startinng f/1.8 and quite sharp at f/2. Add some punch with post processing and on a real photo when f/2 is relevant in term of deph of field and it will be perfect!

For the doll, looking at the shoot @f/4 => We can see the lens is razor sharp... But still most of the subject is not in focus ! The eyes are and elbrow look in focus, but already the mouth and hair in front of the doll are out of focus. Clothes are most out of focus too. And this is f/4.

With so thin deph of field (due to small subject and small distance) how can you expect to see if your lens is sharp or not @f/1.8 with less than twice the deph of field of f/4 that is already too thin?

I really think you should take a look at dof master (Online Depth of Field Calculator). Enter you parameters and you'll understand that this deph of field of f/1.8 is too thin for the subject distance anyway.

Another question for you to solve is why did you focus on 1 instead of 0 on the chart? With a very thin deph of field on must ensure focus is exactly where intended.
07-11-2014, 01:16 PM   #41
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Just a quick note: just got informed today that booth my k-5IIs and my K-30 are on their way back to me from service. So I will be able to check my FA31 once more.

Last edited by zeitlos; 07-11-2014 at 02:04 PM.
07-15-2014, 11:25 AM - 1 Like   #42
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My two Bodies (K-30 + K5IIs) are back from service. What should I say. The FA31 suddenly looks pretty well on both bodies! Love it!

07-15-2014, 07:10 PM - 1 Like   #43
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QuoteOriginally posted by zeitlos Quote
What should I say. The FA31 suddenly looks pretty well on both bodies!
Great news!
08-06-2014, 07:09 AM - 1 Like   #44
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Still having fun with my FA31

Last edited by zeitlos; 03-02-2016 at 12:59 PM.
08-06-2014, 10:04 AM   #45
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QuoteOriginally posted by tibbitts Quote
I'm not an expert, but I'd never use a 3d subject to test a lens. It's hard enough to get exactly perpendicular to a flat object, but at least when you do you don't have DOF issues, except for focus field curvature (but that's another story.)

...but you can get (auto) focus issues when shooting a flat subject and this is what I suspect many of the online tests is all about.
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