Contax G2 TTL and Red Filters

[Peter_S]

Hi!

I keep reading that some ttl meters have troubles with red and orange filters. Does anybody here have experience how the G2 metering behaves with red filters? I use a B+W (x5) red, but have shot too little to draw conclusions yet (so far it seems to work well)

Cheers,
Peter

 

[Doug]

The issue is really the amount of discrepancy in spectral sensitivity between the meter and the film. The types of meter cells will make some difference, and with films, for instance, Ilford's chromogenic XP2 is more red-sensitive than Tri-X.

Just speaking generally, it's not unusual for film to be more blue-sensitive and less red-sensitive than the meter. So indoors with reddish incandescent light, or outdoors with a red or orange filter, the meter "sees" stronger light than the film, resulting in underexposure.

As a start, Peter, I'd give it a half or full stop more than the meter suggests, and then bracket exposures in that direction and see how your gear and film works best.

 

[sevo]

As it is mostly a issue of the film (light meters tend to have a fairly linear response to match colour film), you'll have to test the films you want to use. None of the film spec sheets I know have adjustment factors for TTL though-the-filter metering, all they give is the factor for hand-held meters.

 

[Dwig]

The subject plays a large factor in this issue. In fact, it is often the largest factor. Any time that the subject is composed of strongly colored dominant objects metering through this type of filter is likely to give poor results. Only when the mix of the subject colors averages near neutral will metering through a strong "contrast" filter yield successful results.

If you are using a red filter to darken the sky and the sky is a large portion of the subject then metering through the filter will give the wrong reading unless you are taking spot readings and doing Zone System calculations. A averaging reading will certainly result in the sky not being darkened as much as expected.

 

[Peter_S]

Doug, Sevo and Dwig,

thank you for the through-out explanations. That film, light and sky-to-non-sky ratio are variables here makes now total sense.

Cheers, I appreciate it!
Peter