07-29-2011, 11:23 PM
I just had an idea that might be a little crazy, but I think might be worth a try.
Does anyone know their filter gel characteristics? I'm looking for one that passes red and blue, but blocks green. Something like Congo Blue is close, but that passes blue and IR. If there's one that shifts the red range up a bit that will be ideal.
Why do I want this? I wonder what the DSLR phase AF sensors are like to colour? I have to assume they're somewhat panchromic otherwise they wouldn't work with some monochromatic targets. I suspect that for a lot of "near misses" I get with tracking AF of smaller or darker subjects, the AF system is picking green items nearby in preference. If I can slide in a gel to modify the AF response (possibly needing minor offset correction) that might help.
Does anyone know their filter gel characteristics? I'm looking for one that passes red and blue, but blocks green. Something like Congo Blue is close, but that passes blue and IR. If there's one that shifts the red range up a bit that will be ideal.
Why do I want this? I wonder what the DSLR phase AF sensors are like to colour? I have to assume they're somewhat panchromic otherwise they wouldn't work with some monochromatic targets. I suspect that for a lot of "near misses" I get with tracking AF of smaller or darker subjects, the AF system is picking green items nearby in preference. If I can slide in a gel to modify the AF response (possibly needing minor offset correction) that might help.
<a class="bbc_url" href="http://snowporing.deviantart.com/">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.