Lab values for Sekonic Exposure Target II

Started Mar 31, 2012 | Discussions thread
ComputerDork
Regular MemberPosts: 225
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Re: Could still use at least 3 spot readings.....
In reply to ComputerDork, Apr 3, 2012

Just in case people think I'm asking for pointless information:

I took a reading off of the gray card side of the Lastolie EzyBalance I use (which Lee Varis likes, BTW) and the ColorMunki spot reading utility (ColorPicker) said L=45 which means that (according to the Bruce Lindbloom calculator) Y=14.54%

I've tested the colormunki by measuring various patches from a ColorChecker chart and they were very close to the published numbers for the illuminant, so I'm pretty sure the ColorMunki is reading correctly. I also tested it by printing an L=50,a=0,b=0 patch on my printer in absolute colorimetric mode using a custom profile and that came back L=50 though I guess that doesn't mean much since that particular spectrophotometer was used to create the profile used.

Also, as Lee Varis said, light meters are actually calibrated to read for some ANSI-specified reflectance of 12.3% so this also has me wondering if the sekonic target "18%" patch is really something else considering that it's made for calibrating light meters. He also mentions that 12.3% is supposed to be closer to L=50 but according to that calculator it would be more like L=41.7% so I'm not sure what's up with that.

Anyway, given that there seems to be some disagreement here among manufacturers I'm curious as to what Sekonic decided on for this target. (It would also just be nice to know how accurate they decided they needed to get with the intemediate patches.)

BTW, I like Lee Varis' stuff and have been reading his zone system book. It was just what I was looking for, and what got me to thinking about all of this.

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