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01-13-2015, 12:12 PM   #1
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Adapted lenses, hazy centers?

Hey guys, I've noticed some of my photos with adapted lenses occasionally get a hazy center (usually bluish) - almost like a fog.....has this been addressed and might anyone know what the cause is?

The only thing I can add is that it usually happens at larger apertures and when stopped down it becomes almost non existent- is this some of optical character of certain lenses?

Thanks-

01-13-2015, 12:14 PM   #2
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Most probably the character of the lenses that is amplified on that little sensor.
Stopping down the lens and finding its sweet spot is the best answer. You won't be able to fix this.
01-13-2015, 12:15 PM   #3
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Example pictures and lens info?
01-13-2015, 12:44 PM   #4
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I once had a hazy center image after using adapted lenses - I had left my fingerprint on the sensor cover.
For my Pentax DSLR I've got a 1970s Tamron adap-all 90mm macro. A great lens with on defect: The back lens is flat where it faces to the sensor and occasionally I get a blueish spot in the center. The spot is getting smaller and brighter when I close the aperture.

With the Q I would try to limit the transmission of unused light. Maybe you can put a black cardboard disc with a small rectangular hole in the front filter thread to do this and check again. At least the contrast will improve in many images. With a photo editor it should even be possible to quanify the gain.

01-13-2015, 12:52 PM   #5
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Unrelated to the blue you may want to use longer narrower hoods because of the crop factor to improve your overall results.

Last edited by UncleVanya; 01-13-2015 at 01:53 PM.
01-13-2015, 01:05 PM   #6
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Sounds like an internal reflection off the sensor (didn't happen with film), but usually the opposite is seen as described by Altglas: gets more noticeable as you stop down and is hardly or not visible wide-open. Usually caused by flat rear element, internal paint loss in the lens (Schneideritis), aperture blades that are too shiny on the rear side, etc...
01-13-2015, 01:13 PM   #7
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Can anything improve it, perhaps adding a good Tele converter with a different rear element design? Obviously this will change focal lengths etc.
01-13-2015, 01:26 PM   #8
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Reflective adapter interiors can give various haze and spot effects, though in my experience it's usually worse when stopping down. You can test that by putting just about anything non-reflective over it. I have used a cut off part of a worn out dark blue sock to surprisingly good effect. More than good enough to test if that's the problem.

Some lenses also have this problem (reflective surfaces outside the rear element) on their own, with the same solution.

01-13-2015, 01:28 PM   #9
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This often happens with glassed adapters due to internal reflections. This is a common occurrence, for example, with the Chinese knockoffs of the MetaBones speed boosters.

If you are using non-glassed adapters with shiny black interiors, it can cause this too. Easiest way around it in that case is to paint the interiors with ultra-matte black paint.
01-13-2015, 01:39 PM   #10
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Ah...I didn't even notice we were in the Q forum. Yeah, the cheap K-Q adapters definitely can have this problem -- the interior surface needs to be less reflective. Once done, IQ will be noticeably improved. (The Pentax adapter is very well made and does not need modifcation.)
01-13-2015, 01:45 PM   #11
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QuoteOriginally posted by vonBaloney Quote
Sounds like an internal reflection off the sensor (didn't happen with film), but usually the opposite is seen as described by Altglas: gets more noticeable as you stop down and is hardly or not visible wide-open. Usually caused by flat rear element, internal paint loss in the lens (Schneideritis), aperture blades that are too shiny on the rear side, etc...
QuoteOriginally posted by drougge Quote
Reflective adapter interiors can give various haze and spot effects, though in my experience it's usually worse when stopping down. You can test that by putting just about anything non-reflective over it. I have used a cut off part of a worn out dark blue sock to surprisingly good effect. More than good enough to test if that's the problem.

Some lenses also have this problem (reflective surfaces outside the rear element) on their own, with the same solution.
QuoteOriginally posted by vonBaloney Quote
Ah...I didn't even notice we were in the Q forum. Yeah, the cheap K-Q adapters definitely can have this problem -- the interior surface needs to be less reflective. Once done, IQ will be noticeably improved. (The Pentax adapter is very well made and does not need modifcation.)
I would whole heartedly agree, either the lens itself, or adaptor. We have had users of cheap 645-K adaptors show serious hazing of the image due to shiny parts in the interior and I have a rikenon 135/2.8 screw mount that exhibited the exact problem the OP described, caused by a gloss black rear element retaining ring. The hazing appeared as a faint large donut wide open,mount stopped down became much more a centralized and significant loss of contrast. On the Q, the donut wide open would not be apparent due to the crop factor
01-13-2015, 01:52 PM   #12
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TO the OP, can you look at the inside of your adapter while shining a bright light on it and see if it is reflective? If so perhaps painting it flat black will solve your issues.
01-13-2015, 02:11 PM   #13
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QuoteOriginally posted by SteveNunez Quote
Hey guys, I've noticed some of my photos with adapted lenses occasionally get a hazy center (usually bluish) - almost like a fog.....has this been addressed and might anyone know what the cause is?

The only thing I can add is that it usually happens at larger apertures and when stopped down it becomes almost non existent- is this some of optical character of certain lenses?

Thanks-
Yup, common problem with reflection of rear element onto sensor. Nothing wrong with the lens, of course.
01-13-2015, 02:12 PM   #14
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Thanks guys.......noted!
01-13-2015, 10:10 PM   #15
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Retro-reflections off of the mirror-like sensors back onto the uncoated rear optical element(s) of older lenses was one of the main reasons for the adoption of Di coating schemes. You may see a reduction in the spots when there's no specular highlights in the field of view/composition. Attention to lighting can often mitigate that problem.
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