Andrea B. Posted October 20, 2015 Share Posted October 20, 2015 Just for the heck of it I stacked the Baader UVIR-Cut filter and the Baader 610 Red Longpass Filter over my B+W 092 IR-Pass Filter to try to capture the visible red "leakage". There are no surprises, but here it is anyway. Equipment: D600-BB + 105/4.5 UV-Nikkor + Filter Stack( 092IR, UVIR-Cut, 610 Red ) + Sunlight Exposure: f/11 for 1/13" @ ISO-200 White Balance: Preset3 which is an in-camera, visible, white balance preset made under the Baader UVIR-Cut filter in sunlight. Conversion: Photo Ninja in which a D600-BB visible colour profile was assigned but no other edits were made except for a bit of blowout control and some sharpening. Comment: I do not know precisely how tight this filter stack is. There might be a bit of IR getting through or maybe a bit of other visible colour leaking. Here a white balance was made on the middle 99% reflective white standard. Link to comment
nfoto Posted October 20, 2015 Share Posted October 20, 2015 If memory serves, the O-92 allows much more red light through than the Hoya R-72, its 50% point being around 700 nm instead of 720 nm. Link to comment
Andrea B. Posted October 20, 2015 Author Share Posted October 20, 2015 Here is the histogram of the raw file. Between EV -1.5 and EV 1, there appears to be only R.From EV -1.5 down to EV -3.3, there is R and G.From Ev -3.3 down to EV -5 we see R, G and B.Below Ev -5 there is no more R. Can we interpret a colour from this histogram? Is the leakage Red? Or is it mostly Red? Link to comment
OlDoinyo Posted October 22, 2015 Share Posted October 22, 2015 I have used the 092 with ordinary black-and-white film as a red filter--about a 5-stop filter factor, as I recall. And, obviously, you can see through it. I would call it a deep-red filter rather than a true black-IR filter. It in fact passes a bit too much red to work very well with Efke's IR film. Link to comment
Andrea B. Posted October 22, 2015 Author Share Posted October 22, 2015 Yes, the 092 is definitely a Red + IR filter. I have it listed that way in the Stickies. "-) Link to comment
nfoto Posted October 22, 2015 Share Posted October 22, 2015 However, it frequently is falsely listed as being an R-72 equivalent. I have at least one sample of a B+W O-92 that you cannot easily look through, and it behaves much the same way as the genuine Hoya R-72. So not really certain what the maker aims to achieve with these filters. Link to comment
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