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You are here: Home / The Last Word / Another medium tele test — white balance

Another medium tele test — white balance

March 9, 2016 JimK 2 Comments

This is a continuation of a test of the following lenses on the Sony a7RII:

  • Zeiss 85mm f/1.8 Batis.
  • Zeiss 85mm f/1.4 Otus.
  • Leica 90mm f/2 Apo Summicron-M ASPH.
  • AF-S Nikkor 85mm f/1.4 G.
  • Sony 90mm f/2.8 FE Macro.

The test starts here.

This post relates to the color testing of the last few posts in this series. In white balancing the third gray patch from teh left in Lightroom, I read the following numbers.

  • Batis: 4100 degrees Kelvin, Tint: -1
  • Otus: 4100 degrees Kelvin, Tint: +1
  • Nikon: 4150 degrees Kelvin, Tint: -1
  • Leica: 4100 degrees Kelvin, Tint: 0
  • Sony: 4250 degrees Kelvin, Tint: 0

You can use the above numbers to estimate the amount and direction of the tint of each lens.

But that’s not what I want to talk about today. You’ll remember that I set the LED lighting panel color temperature to 5000 Kelvin. So what are all the numbers doing about 800 degrees too low? Is the calibration on the LED lighting off?

I took a Sekonic C-500 color temperature meter and aimed it at one of the LED panels. It read 4900 degrees Kelvin with a tint of zero.

So the lights are pretty close to right, or there’s been some collusion between Sekonic and Wescott.

I think this shows how approximate all this raw developer camera color calibration stuff is. The white balance numbers in Lr are useful approximate, relative guides. They bear only incidental relationship to actual color temperatures in the real world.

 

 

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Comments

  1. CarVac says

    March 9, 2016 at 8:38 pm

    WB temperatures and tints are indeed *extremely* arbitrary.

    Reply
    • Jack Hogan says

      March 10, 2016 at 6:55 am

      Right, although great precision does not appear to be needed when using the Forward Matrices and white balancing the raw data off a neutral patch first. Here are the two forward matrices for the a7RII according to Adobe DNG converter, the first one for illuminant A (2850K)
      0.5905 0.2451 0.1288
      0.3221 0.6375 0.0404
      0.1558 0.0001 0.6692
      the second one for D65 (6500K)
      0.5405 0.2586 0.1653
      0.3122 0.6366 0.0512
      0.1445 0.0002 0.6804

      They are interpolated linearly by the inverse of the CCT, so it’s not a few hundred Kelvins one way or the other that are going to break the bank.

      Jack

      Reply

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