Coloured filter questions
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    Plays with Light
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    Coloured filter questions

    by Plays with Light » Tue Feb 11, 2014 5:40 pm

    Two simple filter related queries from those in the know, if I can.

    Just read a thread somewhere on the interweb and it mentioned someone using a yellow filter for their monochromatic photography. I was just wondering if digital captures could benefit from some use of coloured filters, if they are heading to be finished as monochrome? Or was that specific to shooting with film? If it is of benefit, I would assume the need to set a custom white balance for the capture, initially. That is, prior to attaching the coloured filter.

    I have a Cokin P filter holder and am interested in trying to reduce the green glow of mercury-vapor lamps as well as the orange glow from sodium-vapor lamps. Am I right to assume I would simply use a coloured filter on the opposite side of the colour wheel to minimise it? That is, for the orange glow of Sodium-vapor lamps you would use a blue/purple colour filter.

    I set a custom white balance for some tricky lighting, with a mixture of street lights and it produced a nightmare of colour for the building concerned! Rectifiable with some heavy handed manipulation in post-production.

    Thanks for any assistance you folks can offer.
    Feedback and honest, constructive criticism is greatly appreciated.
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    Re: Coloured filter questions

    by beeb » Tue Feb 11, 2014 7:24 pm

    Practically speaking, no. If you put a coloured filter on and leave the camera to set the WB automatically it generally will compensate for it anyway, so it's just as easy to shift the WB around - either in camera or (my preference) in post.

    Basically, unless you're aiming to use unedited jpegs SOOC that were shot in B&W, it's so much easier to do it all in post, and a lot more flexible. There could possibly be some slight-to-very negligable gains in low light or in reducing noise or colour blocking, but modern day files are so clean anyway it's not that common the issue pops up, and IMO doesn't warrant carrying around an extra set of filters. Fun for an experiment if you can get some very cheap filters, but largely unneccessary complication otherwise...
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    Re: Coloured filter questions

    by Plays with Light » Tue Feb 11, 2014 7:41 pm

    beeb wrote:Practically speaking, no. If you put a coloured filter on and leave the camera to set the WB automatically it generally will compensate for it anyway, so it's just as easy to shift the WB around - either in camera or (my preference) in post.


    Did you hear the penny drop, Beeb? Thanks for the clue to messing with the in camera white balance. The advanced one, not just shifting the Kelvin scale! I didn't think about that at all, it's a feature I have never used on any camera. I'll check it out now, much easier to take things a tad to the blue/purple on that colour spectrum thing than to mess around in post even... On my camera it's called "WB Shift" and offers you a grid with four sections being Amber, Blue, Magenta and Green. Easy enough to shift things a tad this way and that to see what works for particular lighting... Cool.

    Thanks a million, Beeb! 8)
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    Re: Coloured filter questions

    by Doug » Tue Feb 11, 2014 9:30 pm

    I would use the colour filters in Silver Efex. Not the individual colour sliders (though that might help), but either the (I think there are 5) present (whole image)
    colour filters, or if you are are honing in on the very specific colour temperature of a street lamp then try the colour filter hue slider to find the sweet spot that gives the result you want.

    You are effectively passing all the colours of the image thought a single colour virtual filter, but only seeing the real time effect of doing that in B+W.

    Leica make the only digital camera model I know of the deals with digital as a monochrome medium, it only records tonal not colour information so colour filters are required on its lens when desired, just like a film camera.
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    Re: Coloured filter questions

    by Plays with Light » Tue Feb 11, 2014 10:24 pm

    Doug wrote:I would use the colour filters in Silver Efex. Not the individual colour sliders (though that might help), but either the (I think there are 5) present (whole image)
    colour filters, or if you are are honing in on the very specific colour temperature of a street lamp then try the colour filter hue slider to find the sweet spot that gives the result you want.

    You are effectively passing all the colours of the image thought a single colour virtual filter, but only seeing the real time effect of doing that in B+W.

    Leica make the only digital camera model I know of the deals with digital as a monochrome medium, it only records tonal not colour information so colour filters are required on its lens when desired, just like a film camera.


    Thanks for that, Doug. I had a play with that on a picture and compared it to masking and using some filters in photoshop, then going to Silver Efex. I could see a difference between the two versions in regard of tonality of the different treatments. I'm trying to get the differing light sources to appear uniform(ish)...

    Will have a play with (actual) Filters/WB Shift/Photoshop over the next few nights and compare them all to see what works for me. There's a local building hit with the Sodium-vapor lighting on one side and the Mercury-vapor on the other side, which is easy enough for me to get to and test it all out on. Ultimately, I'd like to be able to present night images in colour as well, not just in monochrome.
    Feedback and honest, constructive criticism is greatly appreciated.
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    Re: Coloured filter questions

    by Eden » Wed Feb 12, 2014 2:02 am

    red glasses counter red lasers and green for green

    this would be the same for masking light spectrums would it not?

    just seems logical or is there something im missing ?


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    Re: Coloured filter questions

    by Plays with Light » Wed Feb 12, 2014 9:40 am

    Eden wrote:red glasses counter red lasers and green for green

    this would be the same for masking light spectrums would it not?

    just seems logical or is there something im missing ?

    eden


    I reckon you are correct, Eden. I got stuck on colours for art and the use of colour filters in post-production, mixing up the way light and its colours work with the artistic application of colour! :oops:
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    Re: Coloured filter questions

    by W G » Wed Feb 12, 2014 9:49 am

    It is so nice for me working in film where all these things happen as they should.
    Walter Glover

    "Photography was not a bastard left by science on the doorstep of art, but a legitimate child of the Western pictorial tradition." —Robert Galassi
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    Re: Coloured filter questions

    by Plays with Light » Wed Feb 12, 2014 10:07 am

    W G wrote:It is so nice for me working in film where all these things happen as they should.


    Cheeky bugga! :wink:

    Just out of interest, Walter. If you were photographing (in colour) a place that had a nightmare mix of two different coloured street lights and it had to be a capture with that light present, would you overcome it with the use of coloured glass filters? Would you need to take a couple of frames with different filter treatments to even out the two different sources of light? Then combine them in the darkroom?

    I'm trying to work out for myself how to approach this particular scenario and I have a feeling I will end up doing something along the lines of what I have queried just now... Compositing the two filtered images (one for each light cast) and maybe a neutral third in post-production.
    Feedback and honest, constructive criticism is greatly appreciated.

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