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What Filter is this?


de-JTC

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Hello everyone,

I recently bought a beautiful 5cm Screwmount Summicron in perfect shape. With it I got three filters.

I can't identify one of them.

The seller described it as a polariser.

It is transparent (some yellow streaks) and has a turning mount with numbers from 0 to 17 on it.

Can someone help me?

Thanks in advance,

Jan

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Thanks guys,

I decided to give the glass-replacement a shot.

So I unscrewed the ring on the front and found the really thick polarizer-glass beneath, fixed with a kind of black lacquer. After removal of the lacquer I tried to fit in the glass of a Leica OR 39mm filter and it was a perfect fit. I'll buy a 39mm UV filter for protection and put that in until I find something more interesting to do with it.

Thanks again everyone!

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Hello de-JTC,

 

Welcome to the Forum.

 

You are lucky to have a rotating polarizing filter. It is a useful & practical accessory.

 

The reason the glass portion is so thick is that it is a "sandwich". An optically very flat glass on each side with a piece of highest quality polarizing film in the middle. Leitz always bought the best quality polarizing film to put inside their "sandwich".

 

The reason for the numbers on the rotating mount is so a person could look thru the filter when it was not on the lens & turn it until the desired effect was attained. Then they could look at the top of the filter to see what number was there. As an example: 6 & 1/2. Then they could screw the filter onto the lens & rotate the mount until the 6 & 1/2 was on the top. Then, after adjusting for the filter factor of around DIN -5 they could take the picture with the polarizing effect they wanted. The filter factor remains constant even if a person varies the polarizing filter's effect.

 

Note: On the "M" this filter was eventually replaced with the 13352 which allowed the polarizing filter mount to be attached to the lens & the filter itself swung out to adjust the polarizing effect. After adjusting the filter thru the range/viewfinder window the filter was swung back over the lens.

 

Back to your filter:

 

You can open your "sandwich" now that it is out of the frame & replace the polarizing film in the middle. Remember to buy a sheet of BEST QUALITY polarizing film. It comes in different quality grades for different purposes.

 

You can use the front & back glasses again after cleaning them properly.

 

Remember:

 

The INSIDE surfaces of the 2 pieces of glass must be pefectly clean & dry when you reassemble & attach together the pieces of the "sandwich". The polarizing film is fragile.

 

Best Regards,

 

Michael

Edited by Michael Geschlecht
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The numbers on the outside do more than tell you how to orient the filter on the camera. Put the number corresponding to the hour of the day at the top and this will usually be about the position of maximum extinction.

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