Hello, Everyone. I use an M6 TTL and primarily shoot b&w. I will be experimenting with filters (Heliopan Yellow/Green 11 & Orange 22) for the first time within the next few weeks. My question is about filter use and exposure settings with the M6 TTL. The manual states: ". . .any reduction in the quantity of light by the filter is automatically taken into account." It goes on to say, ". . .more extreme filters may cause deviations from the correct exposure. For example, orange filters generally require one stop more exposure; red on average two stops more." What experience have you had with the use of filters with the M6 TTL, especially the yellow/green and the orange? Do you find the above "manual advice" consistent with your experience? I appreciate any assistance you may share. Thanks.

-- Max Wall (mtwall@earthlink.net), March 20, 2002

Answers

I don't have a problem with using the yellow/green 11 or orange 22 with the TTL meter on the M6 (I own both filters) but when it comes to the very dark red filter red 29 I rely on incident or spot reflected light readings from my Sekonic for exposure and adjust according to the filter factor. I'm not totally convinced that the spectral response of the SPD in any meter is flat across the vis board... especially when there's a 3 stop enhancement of the border of the vis spectrum (red or blue). And I almost never bracket.... goes against the whole premise of spontaneous photography with the M.

-- John (ouroboros_2001@yahoo.com), March 20, 2002.

Here's a funny thing. I've not shot much B&W at all (something that must be rectified), and with that in mind recently bought a B+W medium yellow filter (factor x2). When I played with it on my M6 the meter reading was identical regardless of whether I had the filter on or not ! The same thing happened with a Nikon F3 and nikon yellow and orange filters. Only the red made a bit of difference there.

Being pretty dumb I can't figure out why this should be. Any suggestions, and what should I do here? Should I compensate manually for the filter or just let the camera handle it?

-- Tim Franklin (tim_franklin@mac.com), March 20, 2002.

This would certainly explain pictures looking a bit underexposed when I do B+W with oranges + yellow/green. Try seeing whether the reading changes with/without the filter in place. I'll try later and tell you what my ttls do. steve

-- Steve Jones (stephenjjones@btopenworld.com), March 20, 2002.

Max:

I don't have an M6, but my experience w/other TTL-metering cameras tells me that your manual is essentially correct. As John Chan noted, light meters are *not* uniformly sensitive across the color spectrum. You should always experiment w/your filters to ensure that you're compensating correctly--as Tim Franklin's experience suggests, you may want to check your readings even w/the lighter filters despite what the manual states. This is 1 area where I find it easier to use a camera without a TTL meter (e.g., M3/M2/M4) because you can just manually dial in the correct compensation factor on your handheld/clip-on meter.

-- Chris Chen (Washington, DC) (furcafe@NOSPAMcris.com), March 20, 2002.

FWIW, I routinely shoot with both of those filters on my M6TTL and make no compensation on the camera -- I simply use what the meter in the camera says to.

:-),

-- Jack Flesher (jbflesher@msn.com), March 20, 2002.

TRY IT. Run a test roll. Find subject matter typical of your work. Make a set of exposure series, @ metered exposure, over and under. With and w/o filters. take notes. Process, proof, examine, decide. It may be you'll have to adjust your E.I. (ASA, ISO). Maybe not. But having run the test, you will know.

-- Mark Sampson (MSampson45@aol.com), March 20, 2002.

Max As an update - with a heliopan orange filter marked 4times (-2stops), both my m6ttls behave in exactly the same way - namely - in tungsten lighting (indoor room lighting) the meter records a half stop loss of light with the filter as compared to without - outdoors in overcast natural light - the meters give 1.5 stops light loss with the filter. So, the manual needs a bit of qualification. What interests me is where "more extreme" cuts in - particularly what the filter factor of the leitz ggr (yellow green in english) ought to be. Looks like I'll have to do some zone tests (yawn). Anyway, I'll let you know when I get around to it. So much for ttl metering...

-- Steve Jones (stephenjjones@btopenworld.com), March 21, 2002.

All of the following (or previous) can influence exposure readings with (or without) filters: filter color, filter intensity, subject color, incident light color (explains why orange filter under tungsten has less effect than in daylight), meter cell spectral sensitivity, film spectral sensitivity (Plus-X and old HP4 were quite a bit less blue- sensitive than Tri-X and gave better cloud/sky separation even WITHOUT filters.)

It's a can of worms that can only be addressed, for critical work, by testing YOUR film, YOUR meter, YOUR filters, and YOUR light.

Leica's recommendations are probably about as good as you can get in an instruction book smaller than a telephone directory. 8^)

-- Andy Piper (apidens@denver.infi.net), March 21, 2002.