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09-09-2014, 05:18 PM   #1
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645Z and SMC Pentax 67 200mm F4 Flare

The SMC Pentax 67 200mm F4 is my second copy of this lens to date, testing it with my 645Z. I'm getting flare that seems to follow the "X" in the viewfinder grid. The flare is real bad stopped down, and tends to clear up by f5.6. I don't see this behavior on my 35mm, 55mm, 75mm or my 135mm lens.


Has anyone else experience this?

Any suggestions?

I'll be calling Pentax tomorrow...


Last edited by BBC5; 09-09-2014 at 08:05 PM. Reason: added image
09-09-2014, 11:58 PM   #2
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Can you try again to post the picture of your flare? I cant see it. Also, I have had some very linear flares when using this P67 200mm on the 645D. Unlike any other flare I have seen in my career. By linear I mean not circular or iris shaped. I will look for an example.
09-10-2014, 08:45 AM   #3
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QuoteOriginally posted by 672 Quote
Can you try again to post the picture of your flare? I cant see it. Also, I have had some very linear flares when using this P67 200mm on the 645D. Unlike any other flare I have seen in my career. By linear I mean not circular or iris shaped. I will look for an example.
Thanks for the reply.
I tried posting an image yesterday, and for some reason it didn't take. I'll try again here...
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09-10-2014, 10:11 AM   #4
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This looks just like a flare I had when I used a rear filter on my 400 Takumar (67). It seemed as though light from the film had reflected back to the flat surface of the polarizing filter and then reflected back to the film as a flare. Since the rear element of the 200 is flat on the sensor side, it could be reflecting back to the sensor. The 200 doesn't do this on film cameras however. Does the 645Z use an AA filter in front of the sensor?

09-10-2014, 12:21 PM   #5
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QuoteOriginally posted by desertscape Quote
This looks just like a flare I had when I used a rear filter on my 400 Takumar (67). It seemed as though light from the film had reflected back to the flat surface of the polarizing filter and then reflected back to the film as a flare. Since the rear element of the 200 is flat on the sensor side, it could be reflecting back to the sensor. The 200 doesn't do this on film cameras however. Does the 645Z use an AA filter in front of the sensor?
The 645Z is a anti-aliasing filter-less design sensor.
I'm starting to wonder what you are saying about the rear glass element may have something to do with the flare?
The P67 200mm does have a much larger rear element than does the other lenses I have.
09-10-2014, 01:24 PM   #6
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QuoteOriginally posted by BBC5 Quote
I'm starting to wonder what you are saying about the rear glass element may have something to do with the flare?
It is just a guess at this point after seeing something similar with a flat surface in front of the film (sensor). Also, I have seen flares like this from adapters when using larger coverage lenses on a smaller sensor. On some adapters, the outer edges of the the larger image circle would not be fully adsorbed by the adapter but reflected to some degree. The light from the adapter would reflect back to the rear element of the lens and then to the film/sensor. Your situation may be a combination of adapter refection and flat rear element. My Zoerk adapter did this on my 35mm camera, so adding anti reflection material to the adapter solved it.
09-10-2014, 04:26 PM   #7
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QuoteOriginally posted by desertscape Quote
It is just a guess at this point after seeing something similar with a flat surface in front of the film (sensor). Also, I have seen flares like this from adapters when using larger coverage lenses on a smaller sensor. On some adapters, the outer edges of the the larger image circle would not be fully adsorbed by the adapter but reflected to some degree. The light from the adapter would reflect back to the rear element of the lens and then to the film/sensor. Your situation may be a combination of adapter refection and flat rear element. My Zoerk adapter did this on my 35mm camera, so adding anti reflection material to the adapter solved it.
What kind of anti reflection material did you use?
09-10-2014, 06:07 PM   #8
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I coated the adapter surface that was reflecting with glue, then put powdered charcoal on that. If you do this, make sure you blow off all the excess charcoal once the glue is dried. It reflects way less than the black anodized surface it covered.

09-10-2014, 06:10 PM   #9
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I think desertscape is correct. Are you using a Pentax adapter? I've never had a flare problem using 67 lenses on a 645D using the Pentax adapter. I have an off-brand 645/K adapter and I saw some unusual flare. I added some anti-reflection material to the adapter which helped. A lens shade appropriate for the sensor helps too.
09-10-2014, 10:10 PM   #10
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I have been using the newer Version of the 67 200/4 on my 645D for quite a while, using the Pentax Adapter. No Problems like this one at all. Hard to believe the 645z sensor acts differently there, the first Thing I'd check is the Adapter.
09-11-2014, 10:32 AM   #11
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Thanks guys for all your help. It was the adapter that was at fault. Yesterday I sprayed the inside of the adapter with flat black paint, and let dry overnight. Today I tested it, and the flare is gone! Again, thanks...
09-17-2014, 12:55 AM   #12
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QuoteOriginally posted by BBC5 Quote
The SMC Pentax 67 200mm F4 is my second copy of this lens to date, testing it with my 645Z. I'm getting flare that seems to follow the "X" in the viewfinder grid. The flare is real bad stopped down, and tends to clear up by f5.6. I don't see this behavior on my 35mm, 55mm, 75mm or my 135mm lens.


Has anyone else experience this?

Any suggestions?

I'll be calling Pentax tomorrow...


were you by chance shooting toward the sun? if so sometime even a lens hood won't always help. I the days before lens hoods, we shot with the sun over our shoulder.
09-17-2014, 12:40 PM   #13
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QuoteOriginally posted by bull drinkwater Quote
were you by chance shooting toward the sun? if so sometime even a lens hood won't always help. I the days before lens hoods, we shot with the sun over our shoulder.
Nope, in fact I got the flare while inside...anyway, it's fixed now!
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