Using red filters on digital cameras ??

Discussion in 'Black and White' started by BigSky1, Mar 12, 2014.

  1. BigSky1

    BigSky1 Mu-43 Regular

    Dec 5, 2012
    Helena, Montana
    You wanted to get folks advice on this. I have a Red 25 and a Dark Red filter that I want to use with my OMD EM5. My goal is to get the dark sky and stark cloud images. I was trying them out today and the results were not good. I shot in monotone and the images were muddy and bad. Any thoughts on this? I know I can get some of these effects processing color images - my preference is to get the image I want using the filter and little processing.

    Thank you.
  2. Crdome

    Crdome Mu-43 Hall of Famer Subscribing Member

    Sep 11, 2011
    West Central Indiana
    I don't use them but friends use circular polarizing filter instead. Others may find my style of shooting peculiar but I always shoot using one point, spot metering. I meter off hot areas or spots to achieve the values I wish in the darker areas.

    Good luck with your 50mm.

  3. nickthetasmaniac

    nickthetasmaniac Mu-43 All-Pro

    Jan 11, 2011
    Get a quality polarising filter. It can be either linear or circular (doesn't make a difference for mirrorless cameras).
  4. agentlossing

    agentlossing Mu-43 Hall of Famer Subscribing Member

    Jun 26, 2013
    Andrew Lossing
    Hmm, not sure that last reply had much to do with the OP!

    Don't use color filters with digital. Remember, the camera's processor tries to interpret the scene as exposed, and come up with results that are within an acceptable range. A color filter just confuses it, as well as lessens the amount of light that gets in and makes the camera hike ISO.

    Instead, shoot in raw and convert. Even free applications like Google picasa have a filtered b&w setting, which can actually be pretty good. Or check out topaz b&w effects for easy filters.

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  5. bassman

    bassman Mu-43 Top Veteran

    Apr 22, 2013
    New Jersey
    The Bassman
    One would use red or other colored filters with B&W film to achieve results as you describe. However, the sensor in your camera is color sensitive, so it's as if you were using that filter with color slide film. It's unlikely to achieve the result you want.
  6. mattia

    mattia Mu-43 Hall of Famer

    May 3, 2012
    The Netherlands
    Polarising filter for increasing contrast (darker blue skies), and if you want darker skies in black and white, just go into photoshop, and use the channel mixer. Or better yet, use Nik Silver Efex Pro.

    The biggest issue for blue skies in bright, bright light is the fact they simply need a different (lower) exposure, which requires either bracketing and exposure blending (i.e. HDR without the over the top look) or the use of a graduated ND filter.

    The only place where I'd use a red filter on a digital camera would be underwater, where white balance adjustment latitude isn't always enough to compensate for all the blue if you're not bringing your own lighting...
  7. OzRay

    OzRay Mu-43 Hall of Famer

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    You don't need filters to get dark skies etc, Lightroom/Photoshop is all that you need. I got these shots by doing just that:



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  8. dwig

    dwig Mu-43 Top Veteran

    Jun 26, 2010
    Key West FL

    There may be a few scientific/forensic situations where using a specific extremely narrow band pass filter will achieve results that can't be replicated in post processing. In general though, the effects of the "contrast" filters commonly used in "olden days" (read; with film) are easily replicated in post processing without the inherent quality loss (flare, corner astigmatism, ...) caused by the addition of the filter. The only commonly used (again, back in the old film days) filter whose effects can't be replicated in post processing is a polarizer, and then it is only the elimination of reflections that can't be replicated. A polarizer's affect on skies is easily replicated in post.
  9. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    I was thinking about this earlier, and it got me wondering. If you put a light red filter on your camera, then custom WB off a grey card, will it give you more latitude in that color before full saturation? Such as a green filter in the forest, bringing down the overall ambient green to neutral, instead of overblowing it?
  10. kwalsh

    kwalsh Mu-43 Top Veteran Subscribing Member

    Mar 3, 2012
    Baltimore, MD
    Yes, this would be related to a technique sometimes called UniWB. If you look at RAW histograms in daylight usually the R and B channels are very far from saturation. If you put a magenta filter on the camera, shoot RAW and then convert with a custom WB you will in fact get images with slightly less noise at base ISO. In your particular example you wouldn't want to use a green filter in the forest - that would make the problem worse - you would want to use a magenta filter instead. Filter should be complementary color to the channel you want to prevent from blowing.
  11. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    Why would you use complimentary? Wouldn't that increase the distance green is from the custom WB, resulting in less latitude? I am just trying to understand this. Red would be complimentary to what other color?
  12. Rudy

    Rudy Mu-43 Top Veteran

    Jan 24, 2013
    Oakland, CA
    A green filter passes green preferentially relative to red and blue, so you would want the complimentary color, i.e. magenta to even out the raw histogram.
    Other than that the idea works, even though the custom white balance only affects the JPEG output (I believe).
    The raw file will still have the color cast, which you would need to deal with in post.
    However that is the whole point as you want the histograms of the three channels balanced to maximize the dynamic range.
    All that being said, it's a lot easier to just take several exposures without a filter and use HDR in post (if your subject is not moving).
  13. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    As others have said, there's no need to use red filters to darken skies because we can do it in post processing due to the fact that the sensor contains pixels capturing separate data for red, green and blue and that data can be used in processing to give similar effects to the various colour filters used with film cameras shooting black and white film, and the degree of the resulting effect can be adjusted in the process. If you use filters then the degree of the effect is limited by the fact that the filter has already changed the balance of the separate channel data.

    But of course there just has to be an exception—wouldn't you know it? That exception is the Leica Monochrom which does not use an RGB filter array and only captures luminance data for each pixel on the sensor. It's a true monochrome sensor, you can't manipulate RGB data with images from the Monochrom because there is no RGB data, and you can use the colour filters used for black and white film photography on the Monochrom to achieve the same effect as they produce with black and white film. At present the Monochrom seems to be the only digital camera for which this is true.
  14. JoeV

    JoeV Mu-43 Regular

    Aug 22, 2012
    Albuquerque, New Mexico, USA
    Joe Van Cleave
    I'm a proponent of in-camera filtration in preference over channel mixer/Photoshop filtration for no other reason than with a color image subsequently converted to a monochrome channel that's dominant in data from one color channel (like red), that channel will be underexposed in camera, because the automatic exposure system of the camera, in adjusting for a color image, is combining exposure data from all three channels.

    Attempting to do a monochrome conversion subsequently in post from a color file, often you'll find your single-color channel of choice will have to be brightened, causing increased shadow noise and lack of dynamic range, because of this intrinsic in-camera under-exposure problem, which glass filters can prevent.

    When you choose the monochrome setting in-camera, the camera is typically choosing information predominantly from the green channel(1). So when filtering red over the lens the effect won't be seen using the in-camera monochrome setting, it's better to record the image as a red color image in-camera (and adjust the exposure in-camera so that the red channel is properly exposed on the histogram, as far to the right without highlight clipping), then you can convert to monochrome in post-processing by choosing the red channel.


    (1) One exception might be some of the Fujifilm X-series cameras (like the X10 that I'm familiar with) which offer in-camera monochrome film-modes that are pre-filtered for yellow or red, adjusting the exposure accordingly at the time of shooting to render a properly exposed image from the selected color channel.
  15. Not sure if anyone mentioned this but the Bayer sensor is comprised of 25% red, 25% blue, and most importantly 50% green photo-sites. They don't react in the exact same manner as B&W negative to filters. Often you can pull detail in a the edges of the dynamic range from the green channel (and interpolation) that are other wise lost in the other two. Filtering (depending on which color) can actually work against you.

    Shoot RAW and do your processing in post.

    Many discovered this when the Leica Monochrom hit the shelves. This camera is a pure B&W camera using a similar sensor as the M9 minus the Bayer and interpolation. What you get is resolution and nice detail.. finer grey tones. Since all of the sensor sites are used only to measure luminosity without the R,G, G,B filter on top, you get a closer approximation to B&W negative behavior and thus the use of B&W filter set is beneficial. But they also noticed that once you blow out the details or loose them in the shadows, it was much more difficult to pull them back in. Once a photo-sight was out of its dynamic range, chances are all of them in that area are also out.... no other channels from which to try and interpolate and pull detail.
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