jamesmck Posted March 15, 2009 Share Posted March 15, 2009 <p>I understand that filters such as yellow and red will behave more or less similarly with standard black and white films and with Kodak and Ilford C-41 chromogenic films. I wonder if the same is true with C-41 color films when scans are converted to monochrome. Might this depend on the exact way the conversion to b/w is done?</p> Link to comment Share on other sites More sharing options...
john_shriver Posted March 15, 2009 Share Posted March 15, 2009 <p>Only if the scan is done by an equal mix of the R, G, and B channels. Plus, the scan must not try to correct for the filter, or the filtered out channels will go noisy.<br> I'd say it's better to do it yourself in the Channel Mixer in Photoshop, or the convert to monochrome function in Picture Window, where you can choose your own mix of the R, G, and B channels, giving any effective filtration. (It's not exactly the same as a real filter, but close.)</p> Link to comment Share on other sites More sharing options...
lex_jenkins Posted March 15, 2009 Share Posted March 15, 2009 <p>Nope, yellow, orange, red and green "contrast" filters don't work the same way on color films, even with digital grayscale conversion or channel splitting to monochrome. The best bet is to use color films straight, or with whatever color correction, polarizer or other filter you might normally use, and make the adjustments after scanning.</p> <p>In my experience both with color films and digital to grayscale conversion, simply splitting the channels will often produce an effect similar to that of using a contrast filter on b&w film. For example, the red channel of a color scan or digital capture very closely resembles the effect of a #25 red filter on b&w film. The green channel resembles the effect of a green filter on b&w film. And the blue channel is typically uselessly noisy.</p> <p>You can also experiment with HSL and other channel splits for slightly different effects.</p> Link to comment Share on other sites More sharing options...
jamesmck Posted March 15, 2009 Author Share Posted March 15, 2009 <p>Thanks, John and Lex. This is more or less as I expected.</p> Link to comment Share on other sites More sharing options...
galileo42 Posted March 16, 2009 Share Posted March 16, 2009 <p>My experience is that yellow and orange filters with chromogenic b&w result in darker effects than with conventional b&w, especially with blue skies. YMMV.</p> Link to comment Share on other sites More sharing options...
profhlynnjones Posted March 19, 2009 Share Posted March 19, 2009 <p>Why not use the chromogenic filter factors. They are slightly different but so are some of the modern thin emulsion films from the more conventional films.</p> <p>Lynn</p> Link to comment Share on other sites More sharing options...
sfcole Posted March 22, 2009 Share Posted March 22, 2009 <p>Here is an example of CN400 film used with an orange filter:</p><div></div> Link to comment Share on other sites More sharing options...
jamesmck Posted March 26, 2009 Author Share Posted March 26, 2009 <p>Scott: Very impressive photo!<br> Lynn: Not sure what you mean by "chromogenic filter factors."</p> Link to comment Share on other sites More sharing options...
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