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03-14-2008, 07:39 PM   #31
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Yeah it is awesome, until you get to the corners:



03-14-2008, 08:16 PM   #32
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QuoteOriginally posted by benjikan Quote
As I have only had my K20D's for a short time and have been really busy setting up my Ad Agency, I haven't given them a good work out. Now, this may seem strange. I took my 16-50 lens off of the camera to attach another lens. I replaced the 16-50 back on to the camera and decided to re-test it. I made sure it locked tightly when mounting it. I really tightened it well with the confirmed confident click. Now, I am either totally incompetent or something but, I just re-tested the lens and it is working as I might expect it and am working at 800 iso and the stuff looks really good.

I compressed at 7/12 in PS to get under the 1 meg restriction. Therefore JPEG artifacts that are not apparent in the TIFF version.

What's even more incredible, It was shot at f4.0 at 800 iso....

I just don't get it..I am stumped.

Any comments would be appreciated. This whole thing is getting me really neurotic....

Ben

Here it is: Focussed on the right of the BAR CODE.

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Benji, here's a thought...electronic contacts, often, have a bit of manufacturing lube residues and/or metal oxide buildups. After a few cycles of installation/insertion and removal, the contaminants start to wipe off the contacts, improving the electrical conductivity, usually resulting in contact performance closer to design specifications. Might just be enough, sometimes, to make a difference in AF. A possible cause that seems consistent with your reported experience. What do you think, guys?
03-14-2008, 09:20 PM   #33
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Dang Ben, I was gonna let you borrow mine if you hooked me up with one of your supermodel friends. I guess that wont be necessary anymore huh...
03-15-2008, 04:17 AM   #34
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QuoteOriginally posted by Buddha Jones Quote
Dang Ben, I was gonna let you borrow mine if you hooked me up with one of your supermodel friends. I guess that wont be necessary anymore huh...

That can still happen....!!!!!

But seriously folks, the corner resolution although not perfect is very good. The question regarding positive electrical contact could be the reason. I am still confused as to the reason for this. None the less, I won't send the lens back. For now at least...
Here is another test to show corner resolution, unfortunately COMPRESSED 7/12 in PS to get it to load on to this site requiring under 1meg.

Go here to view:

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Ben


03-15-2008, 06:54 AM   #35
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I see the test shot, and at f/2.8 isnt that just OOF area? Oh well, I am going to enjoy mine.
03-15-2008, 02:38 PM   #36
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QuoteOriginally posted by Buddha Jones Quote
I see the test shot, and at f/2.8 isnt that just OOF area? Oh well, I am going to enjoy mine.
Trouble is that shot was at f5.6 not f2.8.
03-15-2008, 03:40 PM   #37
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QuoteOriginally posted by Buddha Jones Quote
I see the test shot, and at f/2.8 isnt that just OOF area? Oh well, I am going to enjoy mine.
Even at the f5.6 aperture, I was very close to the subject and as a result a very shallow depth of field. Point of focus blows out over very short distances.

Ben
03-15-2008, 04:42 PM   #38
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QuoteOriginally posted by benjikan Quote
Even at the f5.6 aperture, I was very close to the subject and as a result a very shallow depth of field. Point of focus blows out over very short distances.
True, DOF was probably less than a cm in this photo.

The lens is acceptable at f5.6. But what about f2.8, f3.5 etc.?

How about posting 100% centre and corner crops of a shot of an average scene in daylight at 4.5-5m at 16mm f2.8? You are at Hyperfocal distance at this range and DOF should cover quite a bit of the scene.

03-16-2008, 01:58 AM   #39
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Ben, reagarding your test images:
I don't understand what exactly you are worrying about.
To me they look sharp (enough) in the plane of focus.
03-16-2008, 06:35 AM   #40
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QuoteOriginally posted by blende8 Quote
Ben, reagarding your test images:
I don't understand what exactly you are worrying about.
To me they look sharp (enough) in the plane of focus.
I agree. I re-tested and have decided NOT to return the lens. In fact all of my lenses seem to have improved in terms of AF performance. I had almost given up on my 21mm Limited and recently tested it and it is like having an entirely new lens. It performs exceptionally now.

Ben
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