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03-27-2011, 12:33 PM   #16
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I wonder if the difference on wheter people have found it or not has to do with the imaging sensor. I found in on my K100D (CCD sensor), and looking back through this thread it seems those reporting it have CCD sensors and those not reporting it have CMOS sensors. Perhaps it is much more noticeable/shows up sooner on the CCD sensors and packages Pentax used than the CMOS ones?

03-27-2011, 03:33 PM   #17
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QuoteOriginally posted by macTak Quote
I wonder if the difference on wheter people have found it or not has to do with the imaging sensor. I found in on my K100D (CCD sensor), and looking back through this thread it seems those reporting it have CCD sensors and those not reporting it have CMOS sensors. Perhaps it is much more noticeable/shows up sooner on the CCD sensors and packages Pentax used than the CMOS ones?
That's interesting, I'll check with the K10D later and see if it's true.
03-28-2011, 10:32 AM   #18
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K10D with 52B has it

Can't remember...pretty sure I tried it on my old Canon 300D and got the same results.
03-28-2011, 11:45 AM   #19
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I've noticed flare occasionally with my K10d and 52BB in situations with strong back or side lighting. The lens hood reduces the problem and overall I quite like the lens.

03-29-2011, 12:11 AM   #20
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Here is my test of 52BB and K10D, on a monopod at f8.0, 16, and 22.

No spot to speak of...

Last edited by excanonfd; 06-15-2011 at 09:00 PM.
03-29-2011, 12:11 AM   #21
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This is a known problem with this lens at certain apertures and light conditions
03-29-2011, 12:14 AM   #22
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Here is 52BB with K100DS, again at f8, 16, and 22

No spot to speak of...

Last edited by excanonfd; 06-15-2011 at 09:00 PM.
03-29-2011, 02:20 AM   #23
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Tamron Adaptall-2 SP 90mm f/2.5 (52B) Lens Reviews - Pentax Third-Party Lens Review Database

The information you seek is present in our own forums in the lens review section. Look at the last line of Nessters' review.

03-29-2011, 03:29 AM   #24
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The blue spot does not show up under all conditions - it has not bothered me in regular outdoor shooting, for example.

Here's a sample of what it looks like: this was at f/11 with 3 strobes

03-29-2011, 10:36 AM   #25
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QuoteOriginally posted by Nesster Quote
The blue spot does not show up under all conditions - it has not bothered me in regular outdoor shooting, for example.
Exactly. I notice it most when there is a lot of white in the frame, like you show. People are going to say "well, the flash(es) must be causing it or there's stray light" or something like that, but it happens no matter where the light source is. Normal use at f/11 or so, it never shows up.

Can't duplicate it shooting a white computer monitor, but I can turn the camera 3 feet to the right and get the spot to show up in the center of a yellow graphic on a white box...
03-29-2011, 10:43 AM   #26
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QuoteOriginally posted by ryan s Quote
Exactly. I notice it most when there is a lot of white in the frame, like you show. People are going to say "well, the flash(es) must be causing it or there's stray light" or something like that, but it happens no matter where the light source is. Normal use at f/11 or so, it never shows up.

Can't duplicate it shooting a white computer monitor, but I can turn the camera 3 feet to the right and get the spot to show up in the center of a yellow graphic on a white box...
are you using the lens's own hood or one made bigger for the narrower FOV of the ASP-C sensor?

Note that origonal hoods for film cameras are too short to provide maximum protection against flare on ASP-C sensors
03-29-2011, 11:02 AM   #27
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I'm not using any hood. Bad, I know, but this sensor flare issue is totally aperture-dependent.

Same scene at f/4 vs f/16, the spot will show up at the smaller aperture. If I get ambitious, I took some pics years ago with the same setup (tripod, lighting, etc) indoors...just have to find them and hope the aperture values are in the Exif...

Edit: These links will save me from diving into my external hard drive The last post in the second thread shows my boredom with the pics I took, even in 2008 when I took them

http://forum.manualfocus.org//viewtopic.php?id=16344
http://forum.manualfocus.org//viewtopic.php?id=9663

Last edited by ryan s; 03-29-2011 at 11:22 AM.
03-29-2011, 12:14 PM   #28
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I haven't read all the reply's (just kinda scanned them) so please forgive me if this duplicates any of the information already given. I don't have time to duplicate the test today but I do own a Tamron 90mm f2.5 (52B) and I can tell you this is a common issue. I've seen the same purple spot and my lens lacks the scratches on the rear element that yours has. It is caused by sensor flair and the flat rear element of the lens. I don't know for sure if it is aperture related. I've found that use of the 01F 2x TC or extension tubes eliminate the problem. Also, others have suggested that a narrower deeper hood should help. There was some discussion on this issue on the Adaptall-2 Lens club. You might want to check it out.
03-29-2011, 02:09 PM   #29
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I just took about 30 shots outside in bright sun with my K10D and a mint condition 52BB, some in Av @f8, f16, f22 and some in Green. I see a distinct hazy purple sphere just left of center, but only in pictures of my charcoal colored cat up on the picnic table; the sphere is very evident in about 9 of the pictures.

I don't see any evidence of it in the other 20+/- pictures I took of newly blooming daffodils and other cats, including a distinctly black and white one; I did not see the purple sphere in her black fur.

Interesting. Might come in handy for doing scyfi photography...
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