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Thread: canon 550D compensating for lighting

  1. #1

    Default canon 550D compensating for lighting

    hi guys

    while im filming with my 550D and i zoom in, the camera seems to compensate for the lighting and changes the lighting everytime i zoom in. can any body tell me how to fix that and prevent it from happening?

    cheers

  2. #2

    Default

    I guess you must be in auto iris mode, find the manual iris mode in the menus. I've never used the camera so can't tell you how to turn it off.

  3. #3

    Default

    Quote Originally Posted by cht377 View Post
    hi guys

    while im filming with my 550D and i zoom in, the camera seems to compensate for the lighting and changes the lighting everytime i zoom in. can any body tell me how to fix that and prevent it from happening?

    cheers
    sounds like an auto exposure issue.

    this may help ....

    exposure lock trouble: Canon EOS 1100D - 300D Forum: Digital Photography Review

  4. #4

    Default

    It may be an auto exposure problem but to me it sounds more related to your lens.

    Expensive lenses have what they call a constant aperture, it sounds like you have a variable aperture lens. If your lens is rated with a max fstop of f1.8 (for e.g.) then it's a constant aperture if f1.8-f4 for e.g.) then it's a variable aperture lens.

    The fstop value is the relationship between the focal length of the lens and the size of the iris. So if you set the iris to a set physical size, when you adjust the zoom the fstop changes causing the difference at either end of the zoom, hence f1.8-f4. This is the fstop value at either end of the zoom when the iris is opened right up.

    Constant aperture lenses compensate for this alowing you to zoom through the lens keeping the same fstop value.

    It's quite important on a video camera if you want to record while zooming. A lot of variable aperture video lenses will let you set the fstop at the narrow end of the lens and keep it constant as you zoom back wider then in again. But if you set it opened at the wide end of the lens and zoom in tight the image will darken as the lens angle tightens. This is because the lens doesn't have any play to open the isis further to compensate.

    Many variable angle slr/dslr lenses don't do this and just change as you zoom through in any direction from any iris setting. With a fully manual variable angle lens like this you would need to adjust the iris and zoom at the same time, but I don't think there are any slr/dslr lenses with a smooth iris adjustment that would allow this.

    David.
    Last edited by david walsh; 05-30-2011 at 02:21 PM.

  5. #5

    Default

    Select ''Manual'' on the dial
    Then go into ''Picture Style'' in settings
    Select ''Neutral''
    Sharpness - all the way down
    Contrast - all the way down
    Saturation - Half way between all the way down and 0
    colour tone - leave as is

    Next go to ''Custom Funtions''
    Select ''C.Fn11:Image''
    Page 3 - Highlight tone priority - 1:Enable

    Iso between 200 and 1250 depending on daylight

    Whitebalance - dont use auto

  6. Default

    Quote Originally Posted by Anto Modded View Post
    Next go to ''Custom Funtions''
    Select ''C.Fn11:Image''
    Page 3 - Highlight tone priority - 1:Enable
    I'd rather have this setting off/disabled.

    Regarding the lighting it sounds like your using the kit lens and it has a variable aperture. Solution, don't zoom in during any pieces of footage you want to use or get a constant aperture zoom, the Sigma 24 - 70 2.8 is pretty nice.

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