Red #25 Filter

W

willgote

Member
Hello all,

Has anyone used a Red #25 filter on the DVX to shoot for black and white?

My background is in non-digital photography, and I know that using a Red 25 when shooting with black and white film increases contrast and darkens the sky. Does the same apply to the digital realm?

So far all of the black and white experimentation I've done has been from adjusting the Master PED and tweaking things in post, and I've been able to achieve some very contrasty Pi-like shots.

I haven't invested in a red 25, and none of my photography lens filters fit the DVX. Just thought I'd ask if anyone knows the effects of a red 25 before I ran out and bought one.

Thanks for your help!
 
There's no need to buy a red filter for a 3 chip video camera. You already have a red filter over one of the chips--or only red light split off to one of the chips. In post you just throw away the green and blue channels and voila--same effect as having shot through a pure red filter. A red filter on the lens will just throw away sensitivity (therefore potentially adding noise).
 
Also, shooting color video is not the same as shooting black and white film, so the filter would not have the same relationship with it. Even if you could turn off the green and blue chips while you record, while the effect would be the same as shooting color video through a red filter, it would not be the same as shooting B/W film with a red filter.
 
In some ways, using the single red channel of a video camera is remarkably similar to using a red filter and b&w film. CCD chips don't inherently record color, but they're panchromatic devices--they have a sensitivity across the spectrum of visible light. Likewise, b&w film is also panchromatic. A red filter or beam splitter stops wavelengths of light outside the red part of the spectrum from hitting the CCD (or film). That's why a blue sky is dramatically darkened with a red filter--the blue part of the spectrum is not transmitted. Of course, b&w film and CCD chips have differerent spectral sensitivity curves, so they don't precisely mimic each other. CCD chips have higher sensitivities at longer wavelengths which is why the blue channel is always the noisiest channel. The sensitivity of CCDs in the visible spectrum is lowest in the blue region. In fact most CCD's can see into the near infra-red, although many cameras filter out that part of the spectrum. The bottom line is you can get a pretty close facsimile to b&w film using a CCD-based device, but it may take some mixing of channels if you want to replicate the look of a particular b&w film stock.
 
Indeed . . . it's a physical similarity, but what the firmware does with the data is different, of course, as you allude.
 
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