Results 1 to 4 of 4

Thread: Meter me this?

  1. #1

    Meter me this?

    After the back button discussion not long ago, some points were brought up that helped me understand some of the problems I've been having with metering.

    I was using the back button focus, reframing and didn't realize I was metering on the half pressed trigger. I thought I was metering along with my focus, which when using spot meter on white egrets in ponds, I was getting blown out birds. Now I know why.

    So now I have my back button focus button and then I have my AFL-AEL button assigned to AEL on release. An extra job for my thumb, but I can now focus, meter on what I want to and then reframe. (don't call me stupid, it works for me...at the moment.)

    Anyway, my question is, does auto WB work in conjunction with the metering? If I matrix meter for exposure does the camera use the same matrix area to WB? If I use the only the spot meter does the camera adjust WB to match the color of light just in the spot area being metered? Just wondering?

  2. #2

    Join Date
    Dec 2011
    Location
    Cobourg, Ontario, Canada
    Posts
    2,509
    Real Name
    Allan Short

    Re: Meter me this?

    Dave I do not know, however if you are shooting raw files then who cares what the WB is as you adjust it to your liking in post production. One problem as I see it is if you use spot exposure on the white egret and lock it, then the overall image will be underexposed. This is because the metered white egret, will be set for middle grey thus the overall image will be underexposed you could correct this by using compensation, now if the egret is a BIF and the sky is brighter than the bird then yes to your method. Any which way if shooting raw files then who cares what the auto WB is as you can adjust in post.

    Cheers: Allan

  3. #3

    Join Date
    Feb 2012
    Location
    Texas
    Posts
    6,956
    Real Name
    Ted

    Re: Meter me this?

    Quote Originally Posted by Texas Dave View Post
    After the back button discussion not long ago, some points were brought up that helped me understand some of the problems I've been having with metering.

    <>

    Anyway, my question is, does auto WB work in conjunction with the metering? If I matrix meter for exposure does the camera use the same matrix area to WB? If I use the only the spot meter does the camera adjust WB to match the color of light just in the spot area being metered? Just wondering?
    I think not. The white balance is applied to the whole image. For simplicity, think of three multipliers for red, green and blue being applied to every pixel in your image (after de-mosaicing). Now, again for simplicity, "auto" assumes that the average hue of your image is neutral and calculates those three multipliers based on that assumption. It's called the "gray world" algorithm. (However, if the scene has large areas of one color, the calculation usually fails and your image will have a color cast). There are much more sophisticated algorithms - too complex to explain here.
    Last edited by xpatUSA; 20th November 2014 at 03:47 PM.

  4. #4

    Join Date
    May 2012
    Location
    northern Virginia suburb of Washington, DC
    Posts
    19,064

    Re: Meter me this?

    Quote Originally Posted by Polar01 View Post
    if you are shooting raw files then who cares what the WB is as you adjust it to your liking in post production.
    The less I have to do during post-processing, the better. Also, the more accurate the exposure, the less noise is produced. White balance affects exposure even if only slightly, as is evidenced by the change in the histogram resulting from a change in the white balance.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •