[quote="Bruce (Camclicker)"]I was shooting a group of roses - deep red - with lush green leaves around and behind the main subject. It was a low light/low contrast morning and had rained earlier, the flowers and leaves were showing rain drops. I metered on the green leaves and placed them on Z-V, the flowers fell about Z V-1/2. I wanted to use a red filter (#90, factor of 5) and opened up 2-1/2 stops. It was a close up shot and I wanted to use a shallow DOF to capture the Bokah in mid tones and the subject roses sharp and with *etched* detail. The exposure after filter factoring was 1/4sec @ f-4.5
After considering your data, observing you print, and reading other posts, I wish to offer a possible explanation of some of your resuts. First the subject roses were backlighted, which always makes it hard to get a meaningful luminescent determination with reflective meters. I use a spot meter for similar situations and compare the reading with an incident reading. In many cases, I have found very high, almost specular readings from light reflected from leaves back lighted in a way very similar to those in your print. It is hard to realize this just by observing the scene or reading with an averaging-type or other reflective meter. You have to admit that the leaves were pretty much over exposed and this could be the reason. Second, your #90 filter, I believe, is the "viewing" filter intended for making a color scene appear monochromic to the observer. I recall that they give an overall brown appearance. I have no idea how b&w film would be affected - sorry.
If possible, in the future you should probably try an incident light metering and use a fill-in flash to bring the foreground up to the desired zone. I would also recommend that you minimize the use of color filtration in such a scenario and explore the use of polarizing filtration to cut down reflective possibly specular light from the leaves - easily said after the fact, right?
As far as DOF affecting exposure - I'll have to say not probable except in cases of in-camera metering that can get confused when metering scenes with high background luminances.
Truly, dr bob.