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david richardson

Krasnogorsk K3 yellow viewfinder?

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Without stating the obvious, you haven't got a light yellow filter on your lens have you ?

There won't be any filters in the viewfinder, but bear in mind this is a cheapo camera so I'd imagine the viewfinder optics may not be coated.

I had a K3 many years ago and remember the viewfinder image looked on the warm side compared with a Bolex.

John S

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David, usually the K3 viewfinder has a yellowish color.
Yellow of your photo, however, seems very strong, but maybe it's just the effect of the photo.
If you are looking for "yellow(ish) viewfinder Krasnogorsk 3" on Goolge, you will find various relevant results.
I had two K3s, the first had a fairly yellow viewfinder, the second a little less.
Obviously, it's a viewfinder problem, nothing yellow will be imprinted on the film.

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Posted (edited)

Mine is a bit yellow too. Not as warm as yours, but as Luigi says, if that's direct sunlight coming in, it's probably accentuated it somewhat. Sunlight photographs warmer than daylight.

Presumably the glue used to fix the finder elements has gone squiffy. Nothing to worry about.

Edited by Mark Dunn

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Does it look like it's a particular coating on the viewfinder? Maybe because it's an olde Russian camera I am a tad more skeptical, but I wonder if it could possibly be Thorium coating. I know lots of old 35mm still lenses (i.e. Pentax Takumar, some Canon and Leica lenses, etc.) had a Thorium coating, which is radioactive. The yellowing indicates it reaching a half-life state of decay. Definitely don't take my word on if this is accurate or not, just curious as to if anyone has considered this. Thanks.

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1 hour ago, Loren Hamilton said:

.. I wonder if it could possibly be Thorium coating. I know lots of old 35mm still lenses (i.e. Pentax Takumar, some Canon and Leica lenses, etc.) had a Thorium coating, which is radioactive. The yellowing indicates it reaching a half-life state of decay. Definitely don't take my word on if this is accurate or not, just curious as to if anyone has considered this. Thanks.

Thorium oxide was used as a component of the glass in some lenses made in the first few post-war decades to enhance certain optical properties, it wasn't used in lens coatings. Soviet lenses don't appear to be among the lenses people have measured to be radioactive, unlike a number of Japanese, German and American lenses from that time, which suggests they didn't use thorium in Russia. It's possible they used Lanthanum, which is much less radioactive, but I don't know how much yellowing that might cause with age. 

This site has a list of some of the lenses that have been measured to be radioactive due to thorium glass, I don't think any are Soviet:

https://camerapedia.fandom.com/wiki/Radioactive_lenses

UV lamp light can reduce the yellow/brown cast caused by decaying thorium, but has no effect on the yellowing caused by old Canada Balsam glue used in doublets and prisms, which is what I would say is most likely causing K3 viewfinders to yellow.  I remember Arri SR viewfinder prisms sometimes had the same problem. But the OP could try a UV lamp down the viewfinder, in case it's Lanthanum glass causing it.

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