Canon 1D M II bug?

Arizona Bill

• December 28, 2004 02:44

If you have a 1D MII could you run a test and see if this is a bug? Set the custom function to allow ISO expansion and then shoot something neutral at iso 50 and iso 100. Open in C1 (I'm using Windows version 3.5.2 of SE) ... the 50 shot looks overexposed by a stop, as if the camera simply shot it that way. But when I open the same raw files in CS RAW the two shots look the same.

It looks to me like C1 doesn't recognize ISO 50 on the Mark II, ie, it treats it like ISO 100.

Can anyone else verify this?

Bill

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  Ulf Liljegren

  • December 28, 2004 12:15

  I can not verify this after test with Capture One 3.5.2 Windows and 3.6.1 on Mac, shoot two images same shutter speed and apeture.
  ISO 50 and ISO 100 and can see one F-stop difference as it should be.

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  Arizona Bill

  • December 28, 2004 18:33

  [quote="UlfLiljegren" wrote:
  I can not verify this after test with Capture One 3.5.2 Windows and 3.6.1 on Mac, shoot two images same shutter speed and apeture.
  ISO 50 and ISO 100 and can see one F-stop difference as it should be.

  
  
  Ulf, thanks for checking this and replying quickly. I put together three jpegs to show the problem I am seeing ... if you cannot duplicate this then perhaps I have a setting wrong somewhere.
  
  I was testing for noise and using Av mode at f/9, varying the ISO from 50 to 1600 in one stop increments, so the shutter speed went from 1/250th to 1/8000th sec.
  
  Here is a jpeg of the c1 screen with the iso 100 image ... the histogram is pretty much the same for the 200, 400, 800 and 1600 images ... http://members.aol.com/bhilton665/iso100_c1.jpg ...
  
  Here is a screen capture of the iso 50 image, which is a lot lighter, indicated by the histogram ... http://members.aol.com/bhilton665/iso50_c1.jpg ...
  
  My initial thought was that Canon does not actually support iso 50 but instead simply overexposes by one stop 😊 Then I happened to see these files in Photoshop's File Browser and noticed the tonality was much closer between images, that is, iso 50 was not noticeably brighter in File Browser. So I converted the iso 50 and 100 images with CS RAW ... here is a screen grab showing the same two files converted with C1 and with CS RAW, with a typical RGB reading noted in the text ... the C1 iso 50 image is much lighter. http://members.aol.com/bhilton665/c1_v_csraw_iso50.jpg
  
  So this is what I'm seeing with the Mark II ... I also have a 1Ds and will test it at iso 50 sometime today.
  
  Can anyone else duplicate this? If not it may be something in my settings is 'funny'.
  
  Thanks for your help.
  
  Bill

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  Arizona Bill

  • December 28, 2004 21:46

  I ran the same basic test on a couple more cameras, a second 1D Mark II and a 1Ds, and both show similar results, that is, the iso 50 image is overexposed in the C1 preview and in the default conversion.
  
  With CS RAW the images are closer in exposure and I also tried the Canon software DPP on all three sets of images and the older FVU on the 1Ds and those also agreed with Photoshop, so I'm definitely seeing an anomaly with C1 SE.
  
  I can get the histograms in C1 to look almost identical with EC ~ + .7 on the iso 100 file or EC ~ - .6 on the iso 50 file.
  
  Thanks for any help.
  
  Bill

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  Ulf Liljegren

  • December 29, 2004 11:00

  When I got the more in depth information on how you recieved your results I have been able to replicate this issue.
  I have brought this forward to R&D and will hopefully have an answer for you shortly.

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  Arizona Bill

  • December 29, 2004 14:39

  [quote="UlfLiljegren" wrote:
  When I got the more in depth information on how you recieved your results I have been able to replicate this issue.
  I have brought this forward to R&D and will hopefully have an answer for you shortly.

  
  
  Thanks Ulf, glad you were able to replicate this.
  
  Bill

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