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December 17th, 2004, 04:00 PM | #16 |
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<<<-- Originally posted by Barry Green :Both cameras are easily capable of resolving the entire grayscale section without crushing to black or blowing out whites. The CamAlign is a nice chart but it doesn't really stress their full latitude capability. -->>>
My understanding of the chart goes like this: If you arrange the lighting/exposure such that the white part of the greyscale is just on 100% zebra and two cams show similar performance down to the black, then the latitude of both cams is within 8/10 ths of a stop of each other - (8 bit video with a 10 step greyscale).
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John Jay Beware ***PLUGGER-BYTES*** |
December 17th, 2004, 04:01 PM | #17 |
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<<<-- Originally posted by Boyd Ostroff :
Yeah.... I'm wondering why we see the noticeable barrell distortion? Was it shot up close with full wide zoom? -->>> Yup, straight from the ministry of silly test charts :)
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John Jay Beware ***PLUGGER-BYTES*** |
December 17th, 2004, 04:21 PM | #18 | |
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Quote:
I shall retest as soon as I can and use a waveform to make sure that all three cameras are peaking on the whitest chip. It'll probably be at least a week though before I can get to it. I do have a DV Rack exposure chart here, I'll test it with my DVX and see if its grayscale is deep enough to stress the DVX, and if so, I could use that to retest with an FX1 sooner... |
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December 17th, 2004, 04:49 PM | #19 |
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we're on the same page then :)
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John Jay Beware ***PLUGGER-BYTES*** |
December 17th, 2004, 05:01 PM | #20 |
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All right, I've got a solution that should work, using the DV Rack exposure chart -- I may not be able to get both ends of the gray scale to fall out of latitude in the same shot, but: setting the light such that the darkest chip responds at 50IRE should get the lightest chips to severely blow out to white, and then doing a second exposure by setting the lightest chip to respond at 50 IRE should get the darkest chips to crush to black. Then, by monitoring the chips with a spotmeter, I should be able to determine how many stops over/under a 50-IRE exposure each camera is able to resolve.
Don't know when I'll get to test it, should be in the next week or so. |
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