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Cyan drift on C/V 12mm


michali

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I've used a number of super wides; 12mm C/V & WATE on my M8 and now also on the M9. Never used filters with these lenses on the M8 and lens detection was always set to "OFF", and never really had too many issues, with cyan drift on the M8.

 

I've just returned from the Classic Yacht Regatta in Monaco with my M9 and followed Sean Reid's advice below, when using the 12mm C/V on the M9. I manually set the lens detection to 16mm.

 

As a rule, cross coding to a longer focal length will decrease cyan drift correction whereas cross coding to a shorter focal length will increase cyan drift correction.

Cheers,

Sean

 

Here are the results:

#1 As it came off the camera, only post processing is converted from DNG to Jpeg in LR.

#2 After applying Cornerfix and then converting from DNG to Jpeg in LR.

 

After running pic #2 through Cornerfix the bottom left corner still shows some signs of contamination. I never tried any shots this time around with lens detection set to "OFF", I will do this tomorrow, if the weather clears up its been bucketing down rain for 2 days now.

 

Having said that, last weekend I tried a few shots with the 12mm C/V on the M9, lens detection set to "OFF" and hardly had any red corners. Here's the link to that post:

http://www.l-camera-forum.com/leica-forum/leica-m9-forum/98466-m9-super-wide-135mm-samples.html

 

I suppose that it's a case of the M9 over compensating or over-correcting. I will also try some shots with the lens detection for the 12mm C/V set to 21mm and let's see what happens......

 

BYTW I've haven't encountered any such issues with the WATE on the M9.

 

The more I use the M9 the more I'm loving it, having said that, I'll continue using my M8 as back up, still a great camera!

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Mike,

 

Very unbalanced case of "pink corners" you have there.

 

Re the CornerFix corrected image, could I ask (a) what version of CornerFix, and (B) if its V1.2, did you have the "Bidirectional Correction" option enabled when you generated the profile?

 

Also, have you tried the CV12 uncoded, just with CornerFix doing the corrections?

 

Sandy

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Sandy- Firstly thanks very much for Cornerfix, I downloaded it this evening for the first time.

 

It's version 1.2 & "Bidirectional Correction" was not enabled. I tried a number of different settings in "Preferences" and followed the suggestions in your PDF guide.

 

FYI "Luminance", "Chroma" and "Anti-alias" all set to 0, seems to give me the best result.

 

I'm going to try shooting tomorrow with the 12mm C/V uncoded and then run it through Cornerfix, I've a feeling this will sort it out.

 

Do you think the cause of the "unbalanced pink corners" is a case of the camera over-correcting?

 

Regards

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Do you think the cause of the "unbalanced pink corners" is a case of the camera over-correcting?

 

Yes, definitely was camera over-correction.

 

For CornerFix, as a general rule:

 

1. When correcting cyan corners, Bidirectional Correction disabled (which is the default) will usually work better, but

 

2. when correcting "pink corners" with CornerFix, you'll almost certainly get better results if you enable Bidirectional Correction

 

Sandy

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Sandy- I tried several shots today with the 12mm C/V & M9 as follows:

Lens coding turned off

Lens coding set to 21mm

Lens coding set to 24mm

I didn't bother with the 16mm lens coding setting as we both agree that the camera is over-correcting at that setting. It also appears to me from the pics below that even at the 21mm setting the camera is over correcting.

 

I ran the pics through corner fix with the following settings:

Lens profile = 12mm C/V, "Bidirectional Correction" was enabled, "Luminance", "Chroma" and "Anti-alias" were all set to 0, seems to give the best result.

 

PIC #1= Coding off pre Cornerfix

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PIC #2=Coding off after Cornerfix

PIC #3=Coding set to 21mm pre Cornerfix

PIC #4=Coding set to 21mm after Cornerfix

PIC #5=Coding set to 24mm pre Cornerfix

PIC #6=Coding set to 24mm after Cornerfix

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  • 2 weeks later...

Eric,

 

Not specifically on michali's situation, but CornerFix should be able to cure the red corners for you. Briefly, the process is as follows:

 

1. Shoot an image of a grey wall or grey card or whatever, with the lens coded as for the situation that's giving the red corners. It needs to be reasonably evenly lit. It should show the same red corners as your other images.

 

2. Use that image to create a profile in CornerFix - Just be sure to enable "Bidirectional Correction" when doing so, seeing as you are correcting for red corners rather than cyan corners.

 

3. Correct your other "red corners" images using the profile you just created.

 

There is a more detailed set of instructions in the PDF file that comes with the CornerFix download.

 

If you're having trouble, send me the image you created in (1) to take a look at.

 

Sandy

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Hello Sandy,

 

I followed the process in the instructions in the PDF file that comes with the CornerFix download however I am still having difficulties.

 

I did not have a grey wall to shoot so photographed an off white wall in our conservatory that was evenly lit, and used that to create the profile.

 

EDIT Sandy, I have just created four profiles and named each one differently, now all appears to be much better. I wonder if previously because I was testing different images to use as the profile and using the same name for each, overwriting the older version somehow it had become corrupted causing the very slight red cast i was seeing?

Edited by EricC
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Eric,

 

A white wall should be fine. First question would be what exactly the difficulties you are having are? But I suggest you send me the DNG of the wall to look at; you can use the "contact me" e-mail address in the PDF, or PM me, and I'll give an e-mail address.

 

Sandy

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