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DavidB
Guest
You would find that B+W 486 won't cut it for the NMOS sensor. Its IR sensitivity is sky high.
How did you go with that testing?With a Baader Planetarium 2" fringe killer filter (pricey) and custom WB, it comes close but not there yet.
With the B+W filter you could try adding a cyan filter. BG39 and the like. I will check those combos shortly.
At the moment I'm not sure about your assertion that the B+W 486 lets through too much IR.
I finally got my camera back last week and have only had limited opportunities to test it, but my testing so far shows decent performance for visible-light work with the 486 filter on. It doesn't match the behaviour of the original internal IR filters exactly, so the default WB settings don't work, but custom WB does a pretty good job.
Going further, custom DNG profiles combined with custom WB (using a Colorchecker Passport) do a great job.
Without the 486 filter there is definite IR "contamination" reflected from various subjects, but with it I haven't noticed any. Even though it's winter at the moment I do have some IR-strong light sources in my studio.
Filters such as the BG39 do their work by absorption, while the 486 does its work by reflection. The IR-blocking filters in most digital cameras involve both (in dual-filter setups like the G-system sensors where the front filter vibrates dust away, the "front" filter is the one with an IR-reflective surface. Absorption filters usually also introduce a cyan cast to the visible wavelengths, and looking down the mount at the sensor it's obvious that this colour cast has gone.
Rather than the sensor being SO IR-sensitive that the 486 "isn't enough", do you think it might be just that this visible cast is throwing off the camera's default WB mechanism?
The primary purpose for my G1 is as an IR camera, but with the B+W 486 filter it's also producing visible images I'm happy with so far.