Deep Red filters and Exposure
Curious as to the exposure compensation you use with deep reds, such as the #29 or equiv?
I recently shot some using TTL metering on the MP with a #29 on and made sure I was being generous and instead got very under exposed negs. I have had this problem before (a long time ago...never followed up on it) and wonder if the camera is 'seeing' more light due to relatively higher meter sensitivity to red than on film?
My B&W filter says it has a filter factor of 8. I did not see what extra exposure the camera was giving (over without the filter) but I suspect at least 3 stops judging by the fact that I was getting two more indicated stops when I used a yellow filter. Judging by the negs I would have needed to have given a good 1-2 MORE stops (over the camera metered exposure) to have had any shadow detail worth speaking using.
Could it be that a prepoderance of blueish light (I was on top of a hill and much of the light in the area was perhaps reflected directly from the sky) means an additional compensation was required. I have not had anything like this with normal red filters and below. I've not used a deep red on the MP before so perhaps the metering is more sensitieve to red light than usual.
Any thoughts? I guess when down to such a small frequency range any changes in the colour of light could have a catastrophic impact on requierd exposure. I guess if the light was largely blue, the filter removed almost all - right?
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Last edited by Turtle : 06-07-2008 at 02:48.