Now Sir Mortimer. What is it?

[barkis]

I acquired this filter from a sale of ex WD stuff many years ago.

Obviously it is a filter of sorts, and probably of German origin. It is overall 3.5" in diameter, and the glass filter

2.4". It has the word. Lichtstromfilter engraved on it. It certainly removes glare from any strong light source, including Sol.

It was not part of any other device at the time I got it, but it is certainly part of a larger piece of equipment. There is a spur gear attached to it's rear, so any movment involved would be rotational. I don't think it is a polarizing filter.

Does anyone have any Idea what it might have been used for?. It is also heavy. about 1kg.

Aircraft camera use pops into my mind, but I really don't know.

[blinky]

The bablefish translation says light current? Means nowt to me!

[daz]

Have no idea what it is Ron, but I fixed the link

[Kaptain Klevtsov]

If it is one half of a polarising filter you should be able to check it by rotating it in front of some polarising sunglasses stuck on your head.

Maybe its a fancy way of adjusting the exposure by using a pair of these?

Captain chaos

[The Warthog]

Lichtstromfilter means something like "light stream filter" so a polarizer would be my best guess.

[barkis]

Have no idea what it is Ron, but I fixed the link

I am very much obliged to you sir.

[Andrew*]

I'm lucky enough to have a German girlfriend, who is lucky enough to have a brother visiting, who is lucky enough to be a keen photographer.

He's never heard of a "Lichtstromfilter", but thought it could be a UV filter. Many SLR users buy a "Skylight" or UV filter for each of their lenses. They have very little colour, like this one, and absorb UV, which can eliminate haze and blue cast.

I think Lichtstrom translates best as "beam of light".

Andrew

[Kaptain Klevtsov]

What about building a spectrometer to see what it filters out? Phil made one here http://stargazerslounge.co.uk/index.php?topic=5219.0

Captain Chaos

[barkis]

I acquired this filter from a sale of ex WD stuff many years ago.

Obviously it is a filter of sorts, and probably of German origin. It is overall 3.5" in diameter, and the glass filter

2.4". It has the word. Lichtstromfilter engraved on it. It certainly removes glare from any strong light source, including Sol.

It was not part of any other device at the time I got it, but it is certainly part of a larger piece of equipment. There is a spur gear attached to it's rear, so any movment involved would be rotational. I don't think it is a polarizing filter.

Does anyone have any Idea what it might have been used for?. It is also heavy. about 1kg.

Aircraft camera use pops into my mind, but I really don't know.

Thank you all for your input. I had a tentative attempt to split the two halves of the cell that enclose this filter. I stopped when it became apparent that there is a liquid between two discs of glass.. Now, when I was a soldier boy, I know that some anti aircraft gunsights had, I was told, a Nitrogen film in a sandwich of glass to prevent misting.

I think the polarizing theory gets the vote.

Thanks again guys.