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CPL & red filters in digital photography

Discussion in 'Colour or Not' started by barry_h, Mar 8, 2010.

  1. barry_h

    barry_h Member

    Hi,

    Im using a Nikon D40 and recently purchased a red filter to use with my Hoya CPL.

    Anyone fancy telling me what to do next?!?!?!?!? Im going on a trip to the highlands later this month and will be doing a LOT of landscape photography and was looking for some advice. For example, what order do the filters go on? Best ISO to work at? Would slow shutter speeds be more beneficial (Obviously this will give cloud and/or water haze) but any other advantages?

    I will also be shooting in colour but mono is really pulling me in these days. Oh and any other advice over and above what I've asked?

    Thanks
     
  2. swanseadave

    swanseadave Well-Known Member

    I really don`t see why you would want to use a red filter with a CPL.One or the other surely.Or am I missing the obvious? :D

    Cheers :cool:
     
  3. ermintrude

    ermintrude Hinkypuff

    You do know that the red filter is only of use if you are making B&W pics right? Just confused as you say you are *planning* to shoot colour even though you like mono...

    You can use the red filter to up contrast for B&W output but the resulting photo wont be any use in colour, it will be red all over...

    Dave: Ive heard people say a polariser and a red filter makes the sky even more dramatic, but Ive never tried it.


    EDIT ignore all my ramblings, my brain obviously skipped the blindingly obvious word ***ALSO***... :eek:
     
  4. mediaman

    mediaman Well-Known Member

    Seem to remember a v long time ago, people used to combine polariser with deep red to get an Infra Red effect, when useing b/w film. Don't know if it would work same way on digital.......try setting camera on b/w mode.....see what happens. good luck.
     
  5. El_Sid

    El_Sid Well-Known Member

    Don't bother.

    Red filters do not have the same effect on digital as they do on B&W film. Monochrome film reproduces a greyscale image based on intensity. Filters, such as red worked by suppressing the blue/green light while allowing red/yellow through largely unchanged. This moves the colour balance of the light away from the one inherent in the film's specifications resulting, with the red filter for instance, in darker skies and foliage and a sharper contrast curve.

    Digital cameras work in colour or more accurately they interpolate the colour from the measured luminosity at each pixel and the colour temperature assigned according to the Bayer pattern filter. The net result is that the processor will simply interpolate the colour as best it can from the data available. The end result will be a picture that appears in various shades of red. Now while this can be converted to greyscale monochrome the end result is generally no better than can be acheived from a normal full colour image and is very often poorer - expecially in contrast and tonal range.

    The only highly coloured filters that I have found that really work on digital are IR filters which largely eliminate visible light leaving the camera to record only the IR copmponent. Even then the resultant image has an overall deep red colour and requires careful processing to produce an effective monochrome result.
     
  6. LargeFormat

    LargeFormat Well-Known Member

    I've done it, with the right sky you can get the blue bits black although I can't help wondering why. :D
     
  7. surf_digby

    surf_digby Well-Known Member

    If you're shooting landscape, then take your tripod and there'll be no need to go below ISO200. Even at f16 or whatever you choose to shoot at, it's unlikely you'll get shutter speeds so slow that the clouds will lose much of their form.

    Can't really say how the two filters will work together, as I do all my digital mono shooting on a D80 that has built in simulated filters. Using the "virtual" red filter and a (real) CPL together really does add a lot of contrast to the sky, but whether or not it works as well optically, I just don't know.

    Look at it this way. You've got the filters. You're taking them with you. You're shooting digital. Put them on. Play about with them. See if you like the results.


    "Seem to remember a v long time ago, people used to combine polariser with deep red to get an Infra Red effect, when useing b/w film. Don't know if it would work same way on digital"
    Red filter (with or without CPL) would give you a pseudo IR black sky if there's plenty of white fluffy clouds to play off, but it would also make your vegetation go dark.
     
  8. CWyatt

    CWyatt Well-Known Member

    There is no reason to use coloured filters with digital cameras. The effects can be re-created with more control in post-processing. Try Silver Efex Pro, that's a top photoshop plug in, although channel-based conversion works fine too.
     
  9. surf_digby

    surf_digby Well-Known Member

    I used filters on digital to get familiar with them for use on film.

    I like shooting directly into mono with digital. It means I don't have to convert them afterwards, leaving me with more time to take more pictures/spend time with family/watch adverts from the 1980s on YouTube.
     

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