A few Canon Digital Rebel XT Questions.

Discussion in 'Canon' started by default, Nov 24, 2005.

  1. default

    default Guest

    1. White balance for compact fluorescent lighting: I have found that the
    tungsten setting looks most realistic, but still slightly off. Is there a
    better way when stuck using this type of light?

    2. The EFS18-55mm kit lens: Is it normal that there is a bit of backlash
    and play in the focus ring? I find it quite annoying and in MF mode, there
    is a little bit of rock motion in the lens as well and it can be seen in the
    eyepiece. Is the lens defective, or is this normal for these lenses?

    3. When using a circular polarizer, it seems that I only need to manually
    compensate the exposure when using the flash. The camera seems to correct
    for it automatically in other circumstances. In most circumstances, a
    polarizer wouldn't be used in flash situations, but there are a few cases
    where it helps and I wanted to verify that this is the correct behaviour.

    Thank you for your responses.
     
    default, Nov 24, 2005
    #1
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  2. default

    Alex Guest

    The tungsten setting is good in a lot of cases but I find I have to tweak in
    PaintShopPro once I've downloaded to the PC. Any good image editor should
    allow the Colour Temperature (in Kelvin) to be changed - have a play with
    this if you get a chance.
    This lens is good for a whole range of situations and have taken some great
    photos with it. That said I have found exactly the same symptoms as you
    mention and I'm sure the focus overshoots sometimes. That said I think this
    lens retails for about £50-70 if you buy it separately so it's cheap and
    chearful at the same time. From what I can see you definitely get better
    quality from investing in decent lenses.
    I haven't tried to use the polariser with a flash as such, but dont
    understand why the camera wouldn't compensate with flash mode on, when it
    does without flash. I sometimes compensate a further 1 stop than the camare
    suggests sometimes as the photos seem to come out underexposed. Not sure on
    that one, maybe the camera meters slightly differently.
    Great camera, really pleased with mine ! Got a prime 50mm F1.8 the other
    day - fantastic 2nd lens !
     
    Alex, Nov 24, 2005
    #2
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  3. default

    Colin D Guest

    Fluorescent lamps do not have a continuous spectrum output, and the
    red/green/blue levels are not consistent with color-temperature settings
    in degrees K, so the best way is to use a custom white balance under the
    ambient illumination. Basically you take a shot of a white or neutral
    gray card under the relevant illumination, and then tell he camera to
    use that shot as the white balance reference. The camera manual
    explains this. You have to set the white balance to the custom WB icon
    by pressing the WB button and navigating to the little
    'butterfly'-shaped icon at lower right of the WB window.
    Quite normal. This characteristic has given rise to the lens being
    called a piece of junk, among other epithets, and I have to say it seems
    cheaply made. However, its performance is surprisingly good, and I have
    done exhibition shots with mine, though I now mostly use a 17-85 USM IS
    lens.
    I don't use a polarizer, so I can't give you an answer on that one.

    Colin D.
     
    Colin D, Nov 24, 2005
    #3
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    Celcius Guest

    When I use the crircular polarizer, if the outside ambient light is low,
    such as under trees, I find that I have to take the polarizer off, up the
    ISO or open up the lens. I use the 17-85 USM IS USM. In such situations, the
    lens will adjust but at 1/30 or less of a second, I would need a tripod. I
    haven't used the flash. Marcel.
     
    Celcius, Nov 24, 2005
    #4
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    Bill Funk Guest

    I have a DRebel, so can't say to this.
    That's normal for this lens. I haven't found it to be a problem; a
    light touch eliminates the rock, and the backlash is so small as to be
    not a problem to me.
    I've never tried using a flash with my polarizer.
     
    Bill Funk, Nov 24, 2005
    #5
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    Rod Williams Guest

    If you shoot in RAW mode it doesn't matter. It is a very quick fix no
    matter what type of lighting.
     
    Rod Williams, Nov 24, 2005
    #6
  7. default

    default Guest

    Thank you. I'll try that. The compact fluorescent behaves quite different
    from full length tubes it seems.
    The lens sells separately here for $299(ca). For this price I wouldn't
    expect it to feel quite so cheap. I'm going to go "feel" a few more of them
    at the stores to see if mine is excessive.

    I suspect that it is because the polarizer blocks half of the flash, which
    is not expected by the camera therefore, I need to compensate by two stops.
    Without the flash, the metering is accurate so no compensation is needed.
    Overall I am very happy with the camera also. I especially like how it is
    quick.
     
    default, Nov 24, 2005
    #7
  8. default

    default Guest

    Thank you for this suggestion. This is exactly what would be required. I
    had forgotten that you can calibrate against a known reference, not just by
    "tweaking".
    It does seem to take good pictures, but I am going to check the lenses on
    some of the demonstrator models anyway. It seems odd that they would make
    it feel so cheap when usually Canon lenses feel pretty good.
     
    default, Nov 24, 2005
    #8
  9. default

    default Guest

    I am going to have to experiment more in this situation. Without the flash,
    the camera seems to compensate correctly automatically with a longer shutter
    speed or a bigger aperture for a given ISO level. In the case of the flash,
    I was using the polarizer to cut glare off of a surface under low light that
    seemed to be polar in nature. The polarizer helped to improve this, but I
    think that the camera is unaware that at least half of the light from the
    flash will not pass the polarizer and therefore doesn't know to compensate
    enough.
     
    default, Nov 24, 2005
    #9
  10. default

    default Guest

    I think I will compare my lens to other ones at the store to see if it is
    excessive then. It sounds like yours is not so loose.
     
    default, Nov 24, 2005
    #10
  11. default

    default Guest

    I will try that. White balance is a post process anyway so if the Canon
    software can correct it, then great. I like to be able to get it right
    while the original scene is still visible to compare the colour for
    accuracy.
     
    default, Nov 24, 2005
    #11
  12. default

    default Guest

    I will try this, thank you. If the Canon software can easily post process
    this, then that probably is the answer. Once I have determined the
    parameters, then I can store it in the camera as well to try to compensate
    the colour during acquisition. Another suggestion was to shoot a white or
    grey sheet in the same light and use that to calibrate the camera's colour.
    It is easier to check that the colour looks accurate when the scene is still
    in view than later to do it by memory at the computer.
     
    default, Nov 24, 2005
    #12
  13. default

    default Guest

    Thank you for your response. The performance of the lens seems pretty good,
    but the feel is very cheap. I will have to compare it against other's to
    see if mine is excessive I seems.
     
    default, Nov 24, 2005
    #13
  14. default

    default Guest

    Hi Anabella,

    I got the lens with the camera as part of the kit price. $299 is what I saw
    them selling for at London Drugs. Camera Warehouse has significantly better
    pricing. Thank you for the link.
     
    default, Nov 25, 2005
    #14
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    Bill Funk Guest

    As Anabella says, $299CA is way too much.
    B&H sells this lens for $140US.
    I guess Walgreens Drugs here in the States would sell it for much
    more. :)
     
    Bill Funk, Nov 25, 2005
    #15
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