What's in the name: filter puzzles

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

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ModelZ
Posts: 15
Joined: Sun Nov 01, 2020 4:34 am
Location: Northern Europe

What's in the name: filter puzzles

Post by ModelZ »

Been lately tinkering with two fluorescence scopes. One DIY and one old school - no ready made cubes here. So you have to figure out how the filters & dichros match up. Its been both fascinating and frustrating.

Part of the problem are the cryptic filter codes. If I have a mystery filter at hand I can try to measure it against my existing short and long pass filters to figure it out what it's about. If I just have a code then what? Well, BP, LP, SP, KP, TK... embedded in somewhere there is a clear hint. Even rudimentary German helps to guess. Found also short code guides in Nikon and Olympus pages. Schott pages are useful and e.g. ultravioletphotography.com has a handy cross ref. for some manufacturer's most common filters.

So my question is this: is there in some dark corner of the net a "filter bible" that some tormented soul who has been fighting these same ghosts has compiled?

Just to hint at these strange flavors... Olympus has Y-filters (yellow long pass) but then there is also e.g. EY455. Dug up some Oly brochures and finally Abramowitz's fluoro book to no avail. E=excitation only, optical quality ok for that but not for the image light train? Or perhaps just Extra? Add on to sharpen the excitation distribution. Oly infos I found are insufficient.

Anyone ever encountered CAT425? Reichert offered it for violet excitation. I suspect it is (interference?) BP filter of some bandwidth at the given peak wavelength. But again, just a guess.

It's not just that manufacturers insist on their own notations, it'd even more dense. Schott is German and Very Logical but what the heck is the thinking behind e.g. the code BG36? Its transmission curve is like a seismograph plot at earthquake while its nearest neighbors on both sided (BG25, BG38, 39 etc.) all have smooth unimodal curves and are mutual relatives (red suppression/IR-block etc.).

Well, this got longish. I go now back to my hole and quietly stare at my little disks...

Cryptically yours, Karl

Pau
Site Admin
Posts: 5269
Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Re: What's in the name: filter puzzles

Post by Pau »

Interesting post, this is a somewhat complex world, often unnecessarily arcane.
So my question is this: is there in some dark corner of the net a "filter bible" that some tormented soul who has been fighting these same ghosts has compiled?
I appreciate the sense of humor.
I don't think that anyone here has access to that hidden "filter bible" but be sure that there are highly skilled members able to answer specific questions on filters.
Pau

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