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135mm apo telyt flare


mb1pb

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Folks

 

I bought a used 135mm apo telyt a few months ago. It has a couple of scratches and a fleck of something inside. I've found that under certain circumstances it shows veiling flare. This is typically when there is light reflected from a cloudy sky that is out of the frame.

 

Is this a feature of the lens or do you think it is consequence of the scratches/dust fleck?

Edited by mb1pb
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I suppose any lens can be made to flare under the right/wrong circumstances, but speaking only for myself and one sample of that lens, I never experienced it.   Not knowing the size or location of the scratches I couldn't say what effect they might be having, but in my experience a fairly flare-resistant lens takes a whole lot of scratches, or internal haze, to cause noticeable flare.  Have you shined a penlight through the front while looking through the back at various angles?  Perhaps there's more in there than meets the naked eye. 

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Actually my copy of the lens is remarkably flare-free, but any lens can be brought to flare. To establish whether yours is more flare-prone because of its damage one would need to do a side-by-side comparison.

An old trick is to fill scratches with black ink.

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The primary source of flare with the 135 APO (see attached) is internal reflection off the inside of the rear lens barrel, if there is bright light just outside the image area. There may also be reflections off the inside of the camera chamber sides, floor, or roof. (Test shots made under the light of our dining-room table chandelier, which is now my "acid test" for checking lens flare performance. Pardon my camera shake in the first image.)

 

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More or less the same thing that causes vigorous flare in the 90mm Tele-Elmarit-M ("thin" version), and occasionally with the 135 Tele-Elmar.

 

All three lenses have a fairly long empty tube aft of the last piece of glass, and while in the APO, it is ribbed and painted matte black, glancing light still reflects quite obviously. The more the lens is extended for close focus, the stronger the flare (if the light is right - or rather, wrong).

 

 

Requires awareness of the lighting, and/or generous use of a lens shade. The built-in one is not all that effective, but fortunately there are many deeper 49mm metal shades out there (notably the one for the Pentax screwmount 105/135/200 lenses) - if one tends to work in contra-jour or complex lighting.

 

Edited by adan
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Thanks guys for taking the time to respond and for the really useful information. The flare in the cat picture is exactly what I get. Maybe it's just a characteristic of the lens, but it is not something I ever saw mentioned in the online reviews. 

 

Per

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