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Author Topic: new questions for LR 4.4 and canon 5dmkiii  (Read 1161 times)
mstevensphoto
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« on: August 16, 2013, 10:59:05 AM »
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Hey folks,
   I just recently wend from the 5dmkII to the mk III. I haven't really changed anything else in my process. I shoot maybe 65% studio, 35% natural light (or natural+strobe). I shoot only raw. I'm noticing two things that strike me as odd and annoying. First, most of my shots of people (which is most of what I shoot) come into lightroom WAY red. I'm looking at pictures of what appears to be a badly sunburned Caucasian woman who wasn't sunburned at all. LR has added +28-+36 in the tint. I don't get why the pics generally come in so red? it's an easy enough batch correct, but still annoying.

   The other thing that's more troublesome for me is the seeming loss of my highlights. I don't know if it's an LR issue or perhaps camera or something needs to change in my use of the camera. If I watch an import of a collection LR will bring images in and for a moment they look just right (while it says "loading..." on the library screen). after the image loads it looks like things went a little nuts and what seemed to be a good photo for a moment is now much more harsh.

ideas? thoughts? things to check?

many thanks
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Vladimirovich
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« Reply #1 on: August 16, 2013, 11:17:37 AM »
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ideas? thoughts? things to check?
start with changing of camera profile selected in LR for your raws... if you do not like the results w/ other camera profiles then

1) make/save a default preset w/ certain adjustments that you find you always do, for example in HSL tab, etc (w/ whatever camera profile selected you still find the most suitable)

2) modify camera profile (either using Adobe DNG profile editor or dump .dcp to .xml and edit baseline exposure correction, curve, remove Adobe's LUTs to make it purely matrix - you might like that better - then compile that back to .dcp = Sandy Mc made a beautiful tool for that, dcptool, google it)

3) use the dumbest way - shot some colorchecker target and create a profile from that (Adobe DNG PE will replace original LUTs while preserving the matrix part of color transform or if using XRite OEM software you might get a new matrix part too... alternatively there is a QPCard target and software)

« Last Edit: August 16, 2013, 11:19:43 AM by Vladimirovich » Logged
Vladimirovich
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« Reply #2 on: August 16, 2013, 11:23:36 AM »
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The other thing that's more troublesome for me is the seeming loss of my highlights.

assuming that 5Dmk3 does not have a different exposure metering vs 5Dmk2 (and sensorwise it is no worse) the issue shall be with Adobe's hidden expocorrections :

1) Adobe has a fixed hidden expocorrection hardcoded for each camera - you can find it by converting to .DNG using Adobe tools (ACR, LR, Adobe DNG converter) and checking a proper tag

and

2) Adobe can store an additional hidden expocorrection on top (resulting will be the sum of two) of hardcoded one in .dcp profiles... dump .dcp to .xml wit dcptool and you shall see it

and alternatively that might also an issue with a camera profile from Adobe... for some cameras and some camera profiles Adobe makes colortransforms by using LUTs a lot vs old way which was mostly using matrices and new profiles for 5Dmk3 might be a reason too.

« Last Edit: August 16, 2013, 11:26:34 AM by Vladimirovich » Logged
Vladimirovich
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« Reply #3 on: August 16, 2013, 11:29:32 AM »
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If I watch an import of a collection LR will bring images in and for a moment they look just right (while it says "loading..." on the library screen).
you see an embedded JPG then
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kaelaria
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« Reply #4 on: August 16, 2013, 12:15:52 PM »
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You simply need to calibrate your camera(s).
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mstevensphoto
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« Reply #5 on: August 16, 2013, 01:30:03 PM »
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fantastic, thanks for the detailed info!!

one question: LUT = ?
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Vladimirovich
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« Reply #6 on: August 16, 2013, 01:50:57 PM »
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fantastic, thanks for the detailed info!!

one question: LUT = ?

LookUp Table

I will quote a more or less correct description from qpcard.com (w/ notes in red)

Quote

A dcp profile has several more options and contains up to seven parts:
One (or two) input matrices
One "reduction" or "correction" matrix
One (or two) input LUT corrections
One output curve
One output LUT correction

... Then the Matrix + LUT corrections takes care of the [scene referred /demosaicked RGB in camera "colors" or non colorimetric "camera color space"/] color and white balance, and translates it into a specified PCS (profile connection space) which in the case of Adobe Camera Raw is ProPhoto RGB /linear gamma, gamma 1/. The reason for the option of using two sets of input matrices/LUTs is that we have to adapt the translation differently depending on the scene input whitebalance.
When the first part (scene to PCS transform) is finished, the dcp applies (optional) output curves or "exposure curves", and after this yet another LUT /Adobe uses "HSV" LUTs/ transform.
A curve affects color - a steeper curve increases saturation and vice versa. The final LUT transform can be seen as a "perceptual" adaptation, where corrections that "just looks right" can be added. You usually don't want a photograph to be just a flat copy of reality, and you might also want to compensate for the way human eyes react to color in bright, mid and dark tones (see "Munsell lines" or "Munsell correction").
« Last Edit: August 16, 2013, 02:01:05 PM by Vladimirovich » Logged
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