Wed 11-Sep-13 11:36 AM | edited Wed 11-Sep-13 11:36 AM by NanoMeter
Thank you Bill. The simple answer is that it just happens sometimes. I believe it may have something to do with the time of day, lighting. These shots were done in filtered shade, and late afternoon light.
I don't really think it has too much to do with the camera (D7000). The lens of course can be extremely important when shooting UV, because most lenses don't transmit UV as deeply as others do. I use a Kuribayashi 35mm lens, which is an older lens from 1959. However, the metallic look probably has little to do with the lens.
The day I shot the above photo I was comparing 4 filters, Baader U, UG5 stack, BG3 stack, and BG25 stack. The photo above was one of the last three stacks mentioned, but I am not sure which one. Here is the Baader U shot, done at the same time. This was shot in RAW, white balanced in CNX2 using marquee, and auto-levels in Photoshop, with no other processing.
Usually the background foliage will be gray, or charcoal, when shot in pure UV (Baader U). It is interesting that this same background foliage effect takes place with all 4 of the filters I was testing, regardless of the foliage color each filter produced, they all had the same metallic look. Some were more copper, gold, etc..
Here is the before/after Baader U version. Original out-of-camera at (top). Marquee WB and auto-levels (bottom). (reload page if you don't see before/after pic)