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Cornerfix For Dummies

Maggie O

Active member
HELP!

Since I don't yet have a coded adapter for my nifty new CV 15mm lens, I downloaded Cornerfix to deal with the vignetting. I followed the instructions and created a profile for the lens, but I must be doing something wrong.

When I bring the new CF flies up in Capture One LE, they're all at least two stops underexposed and, oddly enough, with highlights that are blown all to hell and back. :wtf::wtf::wtf:

Now, if I open the CF files in LightZone, they exposure seems to be OK, but the highlights are still sort of blown out, without looking explicitly blown out. :angry::cussing::wtf:

What to do?!?!?! :cry::cry::cry:
 

scott kirkpatrick

Well-known member
The problem is that the different Raw developers each misunderstand the dng files that CornerFix presents in different ways, so there are options to work around it. The simplest is if you start with a Leica M8 file, select 8bit compressed output format. Then every tool recognizes it as a standard leica file. The only real reason to go to 16 bit output is if you get some faint bands in the corners from vignette correcting shadow values. But if you do want to stay with 16 bit, the choices are:

for Capture One4.0, there's an option to increase everything x4 (since CO4 fails to see a white point level indicator when its current release reads a dng -- they promise to fix this)

for ACR-based (PSCS and LR) you're OK with either setting.

for Aperture, use the standard 16bit setting.

scott
 

sandymc

New member
The Mac version has no such menu.
Maggie,

The Mac forces a slightly different menu structure to Windows, but all the same options are available. On the Mac its CornerFix -> Preferences -> Compression

For Capture One LE, you want: "Level Compression" enabled, "Lossless (Huffman) Compression" disabled, and "Capture One V4 Compatibility" disabled

For Capture One V4, you want "Level Compression" disabled, "Lossless (Huffman) Compression" disabled, and "Capture One V4 Compatibility" enabled

Sandy
 

sandymc

New member
That's not an option on the version I have. Which is odd, since I d/l'ed it all of two days ago.
Ummm, ok, check up what the version number says under CornerFix -> About CornerFix. It should be 0.9.1.9......

If it doesn't, check what the name of the zip file is that you downloaded - it should also have 0.9.1.9 in it....

Regards,

Sandy
 

Maggie O

Active member
Hummm, Cornerfix doesn't seem to really be fixing the corners for me. Here's a shot from yesterday, processed in Cornerfix/C1 and then in ACR CS3. The lens profile matches the lens and aperture (CV15mm @ f16) and lack of IR cut filter, so once again, I'm stumped. The difference is pretty dramatic, as you can see:
 

sandymc

New member
Maggie,

Looks over over-corrected to me. First, check the Luminance and Chroma settings in preferences panel - they should usually be 1.

If that doesn't help, then you have a problem with the profile - run me through how exactly you generated it?

Sandy
 

Maggie O

Active member
OK, both of those settings are at 1. Should I dial one or the other down to 0?

To generate the profile, I photographed some new-fallen, evenly lit snow on the ground with my M8, 15mm lens @ f16 and then loaded it into Cornerfix and clicked on the "Create Profile" menu item. I named the file and saved it to disk.
 

sandymc

New member
Maggie,

The settings of 1 should be fine. I'd be more suspicious of the snow picture; I suspect it wasn't as evenly colored as it may have appeared. Suggest you try a grey card or similar; you also need to make sure the lens detection settings are the same for both the reference shot and the shots you want to correct

Sandy
 

sandymc

New member
Maggie,

Here's a profile for a CV15.............

If this gives you significantly better results, then it's definitely an issues with the reference image

Sandy
 

Maggie O

Active member
Well, after processing a bunch of images, I can say that your profile did the trick! I had to set Chroma to 0 to get rid of red vignetting, but once I did, the files looked great!

Thank you so much, Sandy!
 
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