Dark red filter - exposure compensation needed with TTL metering?

[ymc226]

Using a camera that meters TTL, can I just let the camera calculate exposure or do I need to add an additional stop?

I've read in a single source that red needs additional exposure compensation of +1 with TTL cameras while green/orange/yellow don't need this adjustment.

 

[MattKing]

It will vary with your meter, your film, and the light.

Taking a reading without the filter and applying the filter factor is more reliable in my experience.

 

[brian steinberger]

I agree with Matt. Take a meter reading and then apply the filter factor. Meters are more sensitive to certain colors more than others, thus the reason to not meter through color filters for black and white. Also, a deep red filter factor is listed as 3 stops, but I find it to actually be more like 3 1/2 to 4 stops. Take a shot of a gray card without the filter, then with the filter take shots at +2 1/2, 3, 3 1/2, 4, and 4 1/2 stops and see which shot best matches the gray card in the shot without the filter.

 

[polyglot]

Depends in the difference in spectral sensitivities of the film and meter. TMX would probably require nothing but Acros (not very red-sensitive) might need a little more.

 

[al5256]

I give additional +2/3 stop with red and +1/3 stop with deep yellow for most of the films.

 

[Rick A]

Check the manufacturers specs for factor, and then try it with your camera to see if the meter agrees. take a reading on a gray card without first, then with the filter. If the difference correspondes with specs you are good to go, if not you will have to adjust as necessary. Most cameras will not give the full allowance for red filters, and additional stops must be added. My OM-1's will only give 2 stops for red, and I have to add an extra stop manuallyto reach correct exposure.