Need filter recommendation

Hi Folks:

I am shooting urban architecture. Many of the churches have copper clad steep les. This produces a dull green patina. I want to shoot these steeples against a blue sky with tonal separation. I would like the steeples to be highlighted, wi th some texture, and the sky to be a medium gray. (like a white painted steeple shot against a blue sky with a yellow filter). Does anybody have any filter sugg estions? I am thinking maybe a yellow/green? All ideas welcome. I would rather h ave some imput before I buy. Thanks.

Oh, I forgot. I am using medium speed black & white pancromatic film. (Ilford FP4)

I would first try a polarizer. It will darken the sky, and you might be able to control how much by the polarizing angle. You should probably have a polarizer, in any case, as it is a very useful filter.

A medium yellow, yellow/green or light green filter might work, too, if the polarizer darkens the sky too much. Yellow is perhaps the most useful filter, so again it wouldn't hurt to have it.

If you go to a local camera swap meet, you could probably pick up some used filters just to look through. Your local art supply store might have some colored plastic sheets that you could also use for estimating the effect.

If you don't have a black and white viewing filter, this should be your first purchase. It will give you a good idea as to whether or not you need a filter at all.

I would reccommend a "yellow-orange" filter to highlight the copper while darkening the sky.

I think the copper is oxidized, so it's green, not copper colored. This is tricky, since green and blue are so close. I'd try yellow-green and green to lighten the steeple, but also try orange and maybe deep orange for comparison, to see what it looks like to darken the steeple. Hard to say what yellow will do--depends on how yellow the green is, but try that too. I would probably go out one day and make a test with roll film to see what works before taking out the large format camera.

a #40 or #41 orange filter will generally work well for any outdoor architectural application without being overly dramatic. to specifically highlight a greenish roof against a blue sky, you might want to use a #61 yellow-green filter which will lighten the green and still give you a darkened sky tonality.

My suggestion of a polarizer was based on oxidized copper, thus the separation between the polarized light of the sky, and less polarized reflection by the extremely diffused copper oxide.

If I had a copper oxide steeple (or something) I'd take a look at it. I can't think of any near me.

Another thing to check out would be the cut-off curves for the filters. It would let you see how sharp the difference between green and blue are. Don't forget, too, to check out the spectral sensitivity of the film. Some are much less sensitive to blue.

I think TMax 100, Tmax 3200, and Ilford 3200 have reduced blue sensitivities. TMax 100 (according to Kodak) acts as if it had a light yellow filter; the two 3200 films are frequently used for artificial light, which has less blue, so they balance the dyes to make better use of the colors available.

Thanks for your numerous responses. After your input, and after examining Bernard Suess "Creative Black & White Photography" it seems that the #40 yellow/orange will show the greatest contrast difference. This seems a little counterintuitive, since I suspected #60 yellow/green would transmit all green and block blue. But what the heck, I go with the majority and I will work with the #40 yellow/orange the hardest. Thanks again, I will place my order with B&H this evening.