Color of late Jupiter-3 front coatings?

[Dante_Stella]

What is the expected color of the frontmost coating of a late 1970s Juputer-3? Is it almost colorless? Or should it be yellow?

Thanks!

 

[Wulfthari]

I think it should be yellow/brown, this is a good pic from Fedka:

I've see very late Jupiter 9s from the 80s that are decisively brown, I assume they changed (and improved) the coating increasing flare resistance and contrast.

To be honest I was looking for a black one until I found a mid 60s specimen in excellent conditions.

 

[Ko.Fe.]

70 reported to be amber. 79 - less, next to colorless.
I don't think 70's is late. More in the middle.

I was after black one, which is considered to be more modern.
Actual users told me it is less sharp, but better with colors.

 

[Dante_Stella]

The 1977 one I have in hand is clear-ish - like a B+W filter. Definitely less sharp than an Opton but decent. Not a lot of focus shift. I am seeing rainbow-edged flare under some circumstances. Not sure what is going on there, but the presence of cleaning marks at least tells me it's coated.

Dante

 

[uhoh7]

I know someone who knows and will answer here:

http://www.leicaplace.com/forums/12/

He has seen many many J-3's of all eras