Filters with chromogenic B/W

<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>

<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>

 

<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>

<p>Thanks, John and Lex. This is more or less as I expected.</p>

<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>

<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>

<p>Here is an example of CN400 film used with an orange filter:</p><div></div>

<p>Scott: Very impressive photo!<br>

Lynn: Not sure what you mean by "chromogenic filter factors."</p>