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Digitally processing B&W film images - are on-camera colour filters still relevant?

Discussion in 'Digital Image Editing & Printing' started by Stuart Rook, May 10, 2020.

  1. Stuart Rook

    Stuart Rook New Member


    First post, hopefully in the right place!

    I've recently returned to shooting film. In the 1970's and early 80's I had my own darkroom and developed and printed all my own film and was comfortable with all that malarkey. I mostly shot B&W and would occasionally make use of colour filters, mainly yellow and red, when shooting landscapes on 35mm and 120 roll film.

    I've just started scanning my first batches of negatives using a 30MP Canon EOS R & Canon 100mm L macro lens which seems to work well. I'm prosessing the scans with the Negative Lab Pro in Lightroom CC. I also use NiK Filters, Photoshop and Luminar 4.

    My question is: Do I need to invest in filters for my "new" film cameras? I'm fairly competent with the software above and I'm fairly confident I could manage to emulate the effect of colour filters. I guess I'm looking for someone to validate this belief from their experience or tell me that using the filters on-camera ,when appropriate, will give me a much better result?


  2. EightBitTony

    EightBitTony Well-Known Member

    Hi, I've never used filters on a film camera, so can't compare. However, my limited understanding is that for the visible light spectrum, you can achieve the coloured filter effect using only software without any visible impact on fidelity. The camera sensor has interpolated colours for some pixels, so in theory, there's a small margin of error but I doubt it's visible.
  3. PeteRob

    PeteRob Well-Known Member

    I agree with Tony. Colour filters (as distinct from effects filters) were used to alter contrast when using non-colour film. Digital cameras (with the exception of one Leica model I believe) all return a colour image by using a colour filter mask in front of the sensor. The (R,G,B) values assigned to each pixel* can subsequently be mapped to anything in software, whether for contrast in a mono-conversion or for endless effect in colour. The best way to do this is by working with the raw image file. If you were using the mono-Leica (I’m fairly sure I’m not making this up) then you would need to use filters in front of the lens because the sensor in it doesn’t have a colour mask.

    *individual pixels will measure one of [R,G,B] according to the mask in front of it. Interpolation from neighbours is then used to assign the triplet (R,G,B), to the pixel, these days using 14 bits for each colour. An exception is the Sigma Foveon sensor which does something different.
  4. EightBitTony

    EightBitTony Well-Known Member

    You're not wrong.
  5. Roger_Provins

    Roger_Provins Well-Known Member

    I still use a polarising filter. Not something that can be mimicked digitally.
  6. EightBitTony

    EightBitTony Well-Known Member

    Yes, polarising and ND filters (to some extent) are still beneficial, but I think the original question was about colour filters. Pete made it clear with the 'effects filters' bit.
  7. nimbus

    nimbus Well-Known Member

    It may actually be easier to use colour filters at the time of exposure as you will see the effect on the negative. I'm not quite certain about adding them later as the filter does have an effect on the negative, for example a yellow will accentuate clouds, so you would be starting with a slightly different original.

    BTW if you are photographing them with a digital camera you are not technically scanning them!
  8. PeteRob

    PeteRob Well-Known Member

    Reading this reply I realise that I totally misread the original post as asking whether colour filters should be used on the digital camera. If the purpose is to use the digital camera, instead of a scanner, to duplicate a mono-negative then indeed the film camera used to expose those negatives should use contrast filters (yellow, red, green, blue as desired).


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