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Author Topic: LCC Profiles  (Read 720 times)
fotagf8
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« on: April 20, 2014, 10:14:13 PM »
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I am new to LCC profiles, but after today's outting, I have several questions.  The sky was blue and I used a polarizer.  I created an LCC shot for each shot in which I changed the shift.  I shot the LCC by slowing the shutter speed three stops.  When I applied the LCC profiles to the the images, the sky was almost white.  Does the number of stops used to create the LCC file affect the exposure?  So would two stops slowing of shutter speed have resulted in a better exposure after application of the LCC file to photo?

Second question:  Should I have removed the polarizer when I created the LCC shot?  Since a polarizer will have its own impact on the light rays, I would assume that it is advisable not to remove the polarizer.

Third, question, what happens if the LCC file is underexposed?

Thanks
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BartvanderWolf
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« Reply #1 on: April 21, 2014, 04:38:10 AM »
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I am new to LCC profiles, but after today's outting, I have several questions.  The sky was blue and I used a polarizer.  I created an LCC shot for each shot in which I changed the shift.  I shot the LCC by slowing the shutter speed three stops.

Hi,

If you mean that you've exposed 3 stops more than an average exposure reading, it may be a bit much. I usually use something like an exposure adjustment of +2 EV. Make sure that the LCC is exposed to a bright level, but not clipped.

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When I applied the LCC profiles to the the images, the sky was almost white.  Does the number of stops used to create the LCC file affect the exposure?  So would two stops slowing of shutter speed have resulted in a better exposure after application of the LCC file to photo?

The exact exposure level of thee LCC shouldn't affect exposure. You just want to avoid a noisy LCC, so exposure is usually something like +2 EV. That will make sure that also vignetting and light fall-off will be well exposed with little noise from under exposure.

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Second question:  Should I have removed the polarizer when I created the LCC shot?  Since a polarizer will have its own impact on the light rays, I would assume that it is advisable not to remove the polarizer.

Hard to say, but I'd keep things the same as with the actual scene exposures, so with filter.

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Third, question, what happens if the LCC file is underexposed?

Underexposure will lead to more noise, and thus a lower quality equalization. There are measures in place to avoid the negative impact of underexposure noise as much as possible, but it always helps to use better quality LCCs.

Cheers,
Bart 
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Paul2660
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« Reply #2 on: April 21, 2014, 07:56:19 AM »
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You did not mention camera/lens setup, but curious on that.  You did not mention version of C1, as older versions of C1 do not IMO work as well on the LCC process as 7.x and the wide angle LCC correction. 

In low lighting situations where I have a CL-PL on, I will often remove the CL-PL so allow a faster exposure for the LCC, i.e if I am shooting at 1 to 10 seconds already, I don't want to be at 12 seconds for the LCC.  In normal light, I will leave the CL-PL on and adjust the shutter speed accordingly. 

You can most times not have to shoot a LCC after each shot.  I tend to take a LCC series center, right, left shifts then not take anymore unless the lighting changes dramatically or I change out lenses.

The best way to judge an LCC during exposure is to look at the histogram.  A well exposed LCC should have a narrow band about dead center.  You can be OK if it's just a bit left or right.  On shifts, this band tends to be a bit wider.   If you are shooting a Phase IQ back you can also check the exposure warning, as if you have over exposed the LCC, you will see a red center. 

As I understand the LCC process on a tech camera shot, it should not be working on the exposure of the shot as much as the color casts.  On a shift, then yes the LCC will do a lot to even out the exposure of the shift i.e. left or right sides being darker.  On certain lenses/cameras you may see a slightly brigher center exposure on a center frame and the LCC can help to balance that out. 

I have never seen a properly exposed LCC change the exposure of a shot as you mention. 

As for underexposing a LCC, I would rather have a slightly underexposed LCC than over exposed one.  Capture One does a very good job of working with the LCC to get an even exposure.  Noise in a LCC, should not transfer to the image.  C1` is using the LCC to judge the issues of color cast and even exposure (on shifts) against the original image.

Paul
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Paul Caldwell
Little Rock, Arkansas U.S.
Photography > http://photosofarkansas.com
Blog> http://paulcaldwellphotography.com
fotagf8
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« Reply #3 on: April 22, 2014, 07:22:29 AM »
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Thanks to both of you for your helpful comments.
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