any purpose for yellow/red filters?

Discussion in 'Digital SLR' started by bill a, Feb 9, 2005.

  1. bill a

    bill a Guest

    A newbie question..
    I have some yellow and red filters from b&w film shooting,
    and was wondering if there is any way to utilize with dig camera?
    thanks
    bill
     
    bill a, Feb 9, 2005
    #1
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  2. Are you doing B&W digital? If so, I believe you can use them the
    same as before.
     
    Ben Rosengart, Feb 9, 2005
    #2
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  3. bill a

    Alan Browne Guest

    Sure. Use them and get red or yellowed scenes.

    It's actually a good question for the use of DSLR's in B&W mode. Anyone?

    If an image is taken with a filter and saved in color, will the contrast
    benefits of a red filter or yellow filter appear after conversion to B&W in PS?

    Anyone try both combinations?

    Cheers,
    Alan
     
    Alan Browne, Feb 9, 2005
    #3
  4. bill a

    Owamanga Guest

    If shooting RAW, unless you have a specific scientific reason to use
    these, don't bother with the filters. You'll have much more power and
    control within Photoshop.

    I'll bet there are a number of different ways a DSLR manufacturer can
    do metering, and some may be thrown off with a color filter. As might
    other exposure tools: Apparently for example, Nikon's (and they are
    not alone) histogram is based on just the green channel - this won't
    work well if you filter out all the green light. Auto white balance
    may make things a little crazy too (automatically compensating,
    actually reversing what your filter is doing).

    So, take a standard color photo, and then hit it with Photoshop:
    Image/Adjust/Channel Mixer. Check the 'monochrome' box and move the
    R,G,B sliders until you get the desired BW effect. Try to get the
    R,G,B %'s to add up to roughly 100% to keep the exposure the same.
     
    Owamanga, Feb 9, 2005
    #4
  5. bill a

    bill a Guest

    I wasn't aware that there was a b&w mode.
    My D30 canon may not have that. I haven't found anything on
    that in the user guide.
    bill
     
    bill a, Feb 9, 2005
    #5
  6. bill a

    bill a Guest

    that's exactly the crux of my question, but since i am
    new to both the dslr and photoediting, i figured
    that my experimenting may not tell me much.
    hoping some knowledgeable person has tried it already :>)
    thanks
    bill
     
    bill a, Feb 9, 2005
    #6
  7. The 20D does, but I don't recommend it for shooting JPEG. Better to
    shoot RAW and do a more sophisticated conversion to B&W in Photoshop.
    At least, this is my experience; I'm sure there's someone out there
    who likes the in-camera B&W, and that's valid too. :)

    What's super-cool about the 20D is, you can shoot RAW in B&W mode,
    and you get the same RAW file as ever, but the LCD-screen review
    shows up in B&W.

    Anyway, you could probably use your filters for this kind of
    photography, as I said, though it's true that you can accomplish
    the same effects more flexibly in Photoshop later, as someone
    pointed out.
     
    Ben Rosengart, Feb 9, 2005
    #7
  8. bill a

    me Guest

    I will now talk about equipment I know very little about (re: DCD). Those
    filters darken their opposites before the light strikes B&W film. As such I
    suspect that a DCD records a full color image *before* it converts it to
    B&W, assuming it has the option to do so. I see no way this could work but I
    have been wrong before and this wouldn't be the first time. Ballsy answer
    huh!
    Film best,
    me

    [ducking back into my hole to count rolls of film]
    ;-)
     
    me, Feb 9, 2005
    #8
  9. bill a

    Owamanga Guest

    Well, even if you don't have a B&W mode on the camera, a simple
    one-step 'desaturate' will convert the resulting filtered mess into
    B&W.

    The more I think about it, the less I would recommend using the
    filters.

    The CCD is pre-filtered. Each bayer pixel has a red, green or blue
    filter on it already. This gives Photoshop the ability to lean on
    different amounts of those channels to ultimately generate the B&W
    shot from - and it's a lot easier to visualize when it's changing
    right in front of you.

    Whenever i've done it in the past, it's never been a single channel,
    or dual channel with identical amounts change (which is effectively
    what a standard green, red, or yellow filter would be). It's always a
    fluid mix of the three channels (akin to a yellowy-green,
    purpley-pink, or pale fuschia filter - which of course, don't exist in
    my camera bag)

    Putting a colored filter in front of a DSLR will doubtless make the
    histogram function meaningless, possibly give you exposure issues,
    definitely cuts down the light by a stop or more, risks increasing
    flare, risks introducing vignetting, adds another layer of dirty
    glass, and would definitely cause the white balance and subsequent
    JPEG encoding to go nuts. I just don't see any reason to do it.

    The reason I haven't tried using the traditional technique, is because
    none of my B&W filters fit the weird 67mm lens Nikon put in the D70
    kit. (Brainwave: Use my older lens... ah, so I *can* try this..)

    Anyway, shoot this stuff RAW, no filters. Make your B&W in Photoshop.

    Here's a demo:
    http://luminous-landscape.com/tutorials/b-w_better.shtml

    (The duo-tone stuff is worth a read too)

    More on this, and some discussion:
    http://www.photo.net/equipment/digital/editing/bwconvert/

    If you are a gimp fan:
    http://www.gimpguru.org/Tutorials/Color2BW/


    The most important stage:

    Send the files to mpix.com who can use real silver-based B&W Kodak pro
    paper for their digital prints (the heavy stuff you can cut people
    with). They'll look amazing, I promise... unless, it's pictures of
    plane tails.

    B&W from inkjet can be problematic. Honestly, send them to mpix.
     
    Owamanga, Feb 9, 2005
    #9
  10. Wo! I've been searching high and low for true B&W digital prints.
    THANK YOU!
    Huh?
     
    Ben Rosengart, Feb 9, 2005
    #10
  11. bill a

    Ken Ellis Guest

    My guess is you might find some interesting effects, but considering
    what a digital camera does in trying to identify what colors it
    sees... who knows what ya get. For that matter, if your cam has
    a calibratable white bal...then a few different colored papers will
    sorta do the same thing but less extreme.(use them to set white).

    Re a previous reference to the photosop bw conversion; in the
    "channel Mixer" ; set it to monochrome and then with output
    channel gray, adjust the slider red=+160, green=+140 blue=-200
    and constant =0. You get pretty good contrast with that. Look
    up doge & burn techniques if you want more intense. I especially
    like Image Factory's "Convert to BW Pro" filter.

    On my 20D, it has a bw setting with blue, red, green..etc effects
    and if i didn't have, say photoshop, then i would be more impressed
    with them.

    rgds

    Ken
     
    Ken Ellis, Feb 10, 2005
    #11
  12. bill a

    Ken Ellis Guest

    Oh yeah...they might be nice for sunset/sunrise. Try turning the
    particular color sensitivity in the cam down so it's now too extreme

    Ken
     
    Ken Ellis, Feb 10, 2005
    #12
  13. Shoot a whole roll of color with one of them on your film camera and
    drive the lab nuts trying to correct.
     
    Randall Ainsworth, Feb 10, 2005
    #13
  14. bill a

    Owamanga Guest

    Err.. no matter, it's an obscure reference to a thread in another
    photography NG. My mistake.

    "Unusual sight at Luxembourg Airport"
     
    Owamanga, Feb 10, 2005
    #14
  15. bill a

    JPS Guest

    In message <FxtOd.7151$>,
    Any filter will cause changes to a color image, even after white
    balancing. Each of the three color channels has its own spectral
    response, and the filters that you add effect the response of each
    channel, but in a different way. Two reds that are apart in the
    spectrum may record with the same sensitivity, but when you add the
    filter, one may be more sensitive than the other.

    If you filter so far that you darken certain channels completely (or
    make them too noisy to use), then your b&w image will lose resolution;
    usually dropping to only 71% if only the green channel is used, or 50%
    if only red or blue.

    If your subject is greyscale, you could actually use filters to shift
    channels so far apart in sensitivity that you have more than 12-bits of
    greyscale depth.
    --
     
    JPS, Feb 12, 2005
    #15
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