B&W Filter Question

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A friend has given me some Leica filters (E39) he no longer uses. The filters are red, orange and green. On the filter edge are letters designating the colors: R, Or and GGr.

Can someone please tell me what the factors for these filter are or what f-stop increase to use for them?

Thanks.

-- Jon F. Boettcher (JayBee@trainorders.com), July 22, 2001

Answers

Red filters usually take about 2 1/2 to 3 stops. Orange, about 1 1/2 to 2. Green can be a little tougher to guess without seeing it. There's quite a range of those.

My 1960 Leica manual does give the filter factors for two of the filters you mention, but unfortunately they are given for the films then in use. Today the emulsions are all different. FWIW, the green Leitz filter factor is given as 2.5 in sunlight and 3 in tungsten. For the orange Leitz, 4 stops sunlight and 3 stops tungsten. These numbers are for the Tri-X then extant.

These numbers sound a little excessive. They might be less for modern films, I don't know. As always, You should determine your own factors for your film, meter, and equipment, by bracketing exposures in 1/2 stop increments and selecting the negative that prints best.

-- Bob Fleischman (RFXMAIL@prodigy.net), July 22, 2001.


To all,

Some clarification please. I have a regular M6. Does the light meter read through the lens/hence filter or is the light meter on the M6 "classic" from outside the lens?

I just recently shot a roll with a red and yellow filter B&W film. many of the shots seemed under exposed. Did I miss something with my filters on?

Thanks

-- David S Smith (dssmith3@rmci.net), July 22, 2001.


All M6's read through the lens. The classic differes from the current version only in that it lacks TTL for flash. Thus flash pictures with the classic still need to use the flash gun's auto feature, without getting any control feedback from the camera.

Since your M6 reads through the filter, the meter should have given at least an approximately correct exposure. But the metering cell in the camera has its own spectral curve, which may not fully correct for a filter as extreme as red. It ought to have worked better with the yellow filter, though. Assuming you had the advertised ISO set into the M6's film speed dial, then on the next roll you might, again, try bracketing your exposure to determine where you should set your film speed dial when using that filter.

-- Bob Fleischman (RFXMAIL@prodigy.net), July 22, 2001.


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