How Do you Use a Light Meter and 18% Grey, photographing Art?

Discussion in '35mm Cameras' started by Dr. Slick, Sep 3, 2003.

  1. Dr. Slick

    Dr. Slick Guest

    Hello,

    I've been told to use an 18% grey card
    when using my Canon T70's built-in light meter
    to photograph my paintings.

    But that if i get a light meter, i don't
    need the 18% grey card anymore, right?
    Because the meter instead reads the light
    falling on the subject, right? I just plug in
    the ISO and Aperture, and out comes the shutter
    speed, right? So it really shouldn't matter what
    color the subject is (or how dark or light).

    Additionally, i bought Fuji64T, and i plan
    to get the tungsten lamps (2x500watts should be enough?).

    But i was wondering if these lamps would be usable
    with my 4Mpixel digital camera when it arrives. Or
    would it look like crap?

    Thanks in advance.


    Slick

    http://www.drslick.org/
     
    Dr. Slick, Sep 3, 2003
    #1
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  2. Dr. Slick

    Lionel Guest

    Word has it that on 2 Sep 2003 23:02:41 -0700, in this august forum,
    (Dr. Slick) said:
    Yes, that's good advice.
    You will if you need to do white balance correction, which you probably
    will if you're photographing paintings & need accurate colour.
    Likely no better or worse than it would with a film camera.
     
    Lionel, Sep 3, 2003
    #2
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  3. You have a light meter, it's part of your camera. A hand held light
    meter has the same issues (other than white balance and some also have that)
    as does the one built into the camera. It is possible to measure the actual
    light illuminating the subject rather than the light from subject so you
    would not need the gray card.
     
    Joseph Meehan, Sep 3, 2003
    #3
  4. Dr. Slick

    Richards Guest

    By all means, use a gray card and a hand held meter to check the
    lighting. By moving the gray card to every corner of the painting, you
    can check verify that the illumination is completely even. By including
    the gray card in the photo, you have a known reference point for color
    and density. By using the gray card as a reference for white light
    balance, you have a known standard for balance.

    I also use a Macbeth ColorChecker card along with a gray card. I use
    the gray card to set the white balance with my Nikon D100, and then
    shoot the gray card until the histogram shows that the exposure is
    perfect. Next I shoot the Macbeth ColorChecker to have an accurate
    color/density reference in the photo. Then, without changing any camera
    settings, I remove the gray card and colorchecker from the scene and
    shoot the actual scene (usually bracketing). Finally, in Photoshop, I
    use the image with the gray card and colorchecker to adjust the levels
    and curves and color balance.
     
    Richards, Sep 3, 2003
    #4
  5. Dr. Slick

    Alan Browne Guest

    Yes. Meter in spot or centre weighted. Get up close enough that the
    grey card covers the metering area and a bit more.
    <snip>


    Yes. But: A grey card will give you accurate results regardless of the
    lens mounted. A light meter will give you accurate results but will not
    account for minor differences in light loss between lenses. Your in
    camera meter will compensate for this.
    Yes, place the lamps at 45 deg angles wrt to the painting, each side of,
    and level with the camera. Ensure that no light from the lamps gets
    directly to the camera lens (any mirrors around?). The distance from
    the lamps to the work should be several multiples of the size of the
    painting to ensure even illumination. The further away, the more even
    the lighting.

    After you have determined the exposure, consider the exposure range of
    the image. "survey" the paintings darkest and lightest areas (using the
    in camera spot or ctr-wtd meter) and see how far off the readings are
    from your chosen exposure.

    Paintings have, at most, +/- 2 stops of scene latitude. This will
    squeeze in nicely onto that film. If the shot is for scanning, consider
    overexposing slightly (1/3 to 1/2 stop) to thin out the slide and make
    it easier for the scanner to cope with. For projection expose normally.
    (shoot one of each).

    _If_ you are unsure, bracket in 1/2 stops on each side of the grey card
    reading (5 shots per painting). (This will yield at least one slide for
    projection and one slide for scanning in any case).
    Use the tungsten setting of the camera or filters: 81A (household
    tungsten lights) or 81B (white photoflood). These will cost you about
    1/2 stop of light (your in camera meter will compensate for this, your
    handheld meter will not).

    Other:

    --WHAT LENS? AVOID USING A ZOOM (or find the FL at which it has the
    least distortion). 50, 85, 100mm prime lens' are ideal for this.
    --TRIPOD
    --CABLE RELEASE
    --SHOOT AT 3 STOPS CLOSED FROM WIDE OPEN FOR BEST SHARPNESS
    --MIRROR LOCKUP or TIMER WITH MIRROR LOCKUP (if you have it)
    --AVOID SHOOTING 1/15 sec to 1/125 SEC IF YOU DON'T HAVE MIRROR LOCKUP
    --REMOVE THE "UV" or "Sky" filters.

    If shooting at 3 stops from wide open puts you in the 1/15 to 1/125
    range, then close down 1 more stop and move your lights further away
    until the speed is slower than 1/15 (Tripod and cable release are
    essential).
     
    Alan Browne, Sep 3, 2003
    #5
  6. Dr. Slick

    Don Stauffer Guest

    What they mean is to use the camera's meter, but do manual metering. To
    do this, hold card up in front of painting, and then read what the meter
    says the exposure is. Now, using manual metering/exposure, remove card
    and set camera for that exposure, shooting the painting.
     
    Don Stauffer, Sep 3, 2003
    #6
  7. Dr. Slick

    Dr. Slick Guest


    You mean measure the illuminating light with the camera? By
    placing the camera where the subject would normally be? hmmm...

    I think i'm gonna try the 18% grey, because the light meters seem
    a bit expensive. Does anyone recommend a good light meter, that is
    fairly cheap too?


    Slick
     
    Dr. Slick, Sep 3, 2003
    #7
  8. Dr. Slick

    Jim Waggener Guest

    Photographing paintings is the primary use of my 35mm and 4x5 camera.
    I use a light meter with both to measure incident light falling on the
    canvas.
    Fujichrome 64T is great for copy work. I have two Lowel 750w Omni lights
    setup at 45 degrees to the painting for even illumination. I have not needed
    a gray card.
    Results are excellent. My meter is a Gossen Luna Star F digital. Its
    important to have
    the correct angle on the lights to control reflections, particularly on oil
    paintings.

    Good luck,

    JimW
     
    Jim Waggener, Sep 3, 2003
    #8
  9. ebay. I was really shocked when I went shopping for one, to tell you
    the truth. In fact, I never did get one. Here's a page with prices and
    links to reviews:
    http://www.photographyreview.com/Light,Meters/PLS_3115_913crx.aspx

    There's about 300 listed on ebay. So you can use the above to compare
    with what's available.

    Watch out. If you get too much money wrapped up, you'll be obligated to
    drop your paint brushes and take up photography, just to cap on your
    investment. Just kidding.

    Erik
     
    Erik A. Mattila, Sep 3, 2003
    #9
  10. Dr. Slick

    JPS Guest

    In message <uXh5b.32246$>,
    The light from the subject tells you nothing at all about how bright the
    object is, relatively speaking. The grey card does. I see no point in
    using the camera's dumb exposure algorithms in a studio environment with
    controlled lighting. Use the grey card as is, or with a fixed
    compensation.
    --
     
    JPS, Sep 4, 2003
    #10
  11. Dr. Slick

    Andrew D Guest

    Well no. Imagine, for example that your painting is entirely black. Your
    meter doesn't know this so it tells you to overexpose a little - to
    lighten things up - because it thinks the light is too low. This would
    mean your photo turns out grey.

    Now imagine your painting is entirely white. Your meter now tells you to
    shut things down a little because the light is too bright - and your photo
    turns out grey again. If you expose for grey and use those settings for
    boh photos, then the dark painting will be exposed as being dark and the
    light painting as being light - which is exactly what you want.

    This is similar to what happens 9 times out of 10 when you have photos
    processed by a 1 hour mini-lab. Their machine makes adjustments based on a
    neutral-colour standard. If you take a photo of a gorgeous red sunset,
    chances are your printed photo won't show just how red things were because
    the mini-lab machine assumes you buggered up and tones down the redness.

    Andy D.

    "I'm a great speller - but a hopless tpyist!"
     
    Andrew D, Sep 4, 2003
    #11
  12. Dr. Slick

    Tom or Barb Guest

    Plus be sure to include a shot of just the grey card for the lab (or you) to
    use to adjust color balance for the rest of the prints on the roll.
    Assuming you're using film and a lab that knows how to adjust color balance.
     
    Tom or Barb, Sep 4, 2003
    #12
  13. Dr. Slick

    Dr. Slick Guest

    Do you recommend an amatuer who wants professional
    results (as close as i can get), but not a lot of $, to
    skip the light meter and use a grey card exclusively,
    especially at first?


    ..
    Ok, here's a silly question.. My aperture control has
    labels for 8 and 11, but there is a "click" in between, at
    what i presume to be 9.5 (not labeled).

    Is "one stop" considered going from 8 to 11?

    And 1/2 stop is considered going form 8 to 9.5?

    Right?

    Remove the protective/UV filter on the front? Scary!
    I don't wanna scratch the lens!

    Will it really affect the color?

    Slick
     
    Dr. Slick, Sep 4, 2003
    #13
  14. I've been told to use an 18% grey card
    That is correct, but you will need to manually set
    the aperture and shutter after metering the gray card.
    That is also correct if you use what is called an
    incident meter. Most handheld meters have this
    capability. Do not use a reflected/spot meter
    as this just gets you back to where you were with
    the camera meter.
    2x500 will be fine. You will need a sturdy tripod and a
    shutter release cable at least several inches long to
    isolate vibration from your hand. Keep the lights at a 45
    degree angle on each side and keep both of the lights and
    the camera far enough back so you don't get a direct
    reflection of the lights in the picture. You may find
    this kind of work simpler with a 100mm or longer lens
    because of the working distance and reflection control.

    A slight issue is something called "color temperature".
    The Fuji64T, which is a good choice, is balanced for
    a color temperature of 3100 degrees K. A 500W screw
    base "ECT" lamp has a rated color temperature of 3200
    degrees which is essentially perfect for Fuji64T. The
    more common 500W "EBV" lamps have a 3400 degree rating
    and will produce a slightly cool (blue) cast. The
    color temperature describes the measured physical
    temperature of the filament. Higher physical
    temperatures correspond to bluer or "cooler" emotional
    colors. Lower temperatures correspond to redder or
    "warmer" emotional colors. Standard household bulbs
    are much redder than 500W photo lamps. You can use
    mismatched lamps and film by filtering with color
    correction filters. There are several different
    rating systems but as an example, to use EBV lamps
    with Fuji64T, you could use an R3 decamired filter
    for a perfect match.

    Another possibility is to use 4800 degree blue EBW
    500W lamps with daylight balanced slide film but in
    this case you would probably want to use a B3
    decamired filter for perfect color correction with
    slide film.
    It should look just fine. Most high end digital cameras
    let you adjust the color temperature so you can dial it
    in directly. The tungstens might actually work better
    than flash. Certainly much better than the built in flash.
     
    Bob Kirkpatrick, Sep 4, 2003
    #14
  15. "This is similar to what happens 9 times out of 10 when you have photos
    processed by a 1 hour mini-lab. Their machine makes adjustments based on a
    neutral-colour standard. If you take a photo of a gorgeous red sunset,
    chances are your printed photo won't show just how red things were because
    the mini-lab machine assumes you buggered up and tones down the redness. "

    So do you ask them to print with no compensation?

    Tom - Chicago
     
    Tom - Chicago, Sep 6, 2003
    #15
  16. So you take a grey card pic and tell the lab that that is your standard?

    Tom - Chicago
     
    Tom - Chicago, Sep 6, 2003
    #16
  17. Dr. Slick

    Ken Cashion Guest

    No, you ask the person by name...look at the name tag and say,
    "Hey, Maria, I have a problem here that you can help me with...."
    Explain what you wanted it to look like. If she says she
    can't do that...and she might very well not know how to do it...ask if
    they had a manager or something. (Learn their name.)
    They can do wonderful things with the machines...if they know
    how. In Chicago, you should be able to find a one-hour printer who
    will give you virtually custom processing.
    I shot a roll of negative film on a table top setup. Daylight
    film with tungsten lighting. Half-way through the roll, I realized I
    had not put the color compensating filter on the lens. I did at that
    point.
    The first bunch of images were a different color from the
    second bunch and all of them were to be published in a series on the
    same page.
    I went back (Walmart; small southern town) and gave Louise a
    print from the end and a print from the beginning and asked her to try
    to match the front 8 exposures with anyone following them.
    She did, the prints were published, and no one would know what
    I had done.
    So, learn their names and learn their capabilities...that
    makes a one-hour processor a custom finisher. You are lucky to be in
    a large city and have many choices.

    Ken Cashion
     
    Ken Cashion, Sep 6, 2003
    #17
  18. Reputable labs will gladly re-print for you to get proper color balance.
    Ed
     
    Edwin Pawlowski, Sep 6, 2003
    #18
  19. Dr. Slick

    Don B Guest

    The proper way to use a gray card is to set the camera to full manual,
    spot meter the gray card under the same lighting that your subject is
    going to be under, then shoot the subject, ignoring what your meter
    reads. If you are outside and don't have a gray card there are other
    things that come close to 18% gray, such as green grass. If you are
    Caucasian you can meter the palm of your hand and open up about one
    stop.

    I would suggest that anyone that wants to learn to do some serious
    photography to learn the zone system.

    Don
     
    Don B, Sep 8, 2003
    #19
  20. Bringing a pan of homemade brownies doesn't hurt, either, Ken.
    I'm shameless and transparent: My car mechanics get brownies every time
    I bring the car in for an oil change or whatever. I'm their favorite
    customer. :)
     
    Melba's Jammin', Sep 8, 2003
    #20
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