How bad does the cyan get?

[marknorton]

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We know that with an IR filter in place, there's red vignetting with wide angles leading to cyan into the image edges and corners which gets worse the wider you go.

 

This is of course an issue with the WATE and in another thread, we've been discussing how the camera can handle it if it doesn't know the lens selected focal length.

 

I don't have any IR filters yet. I'm wondering if there's anyone out there with the CV 15 and a big enough filter held up in front of the lens who could post some pictures of just how bad it gets without any in-camera or other correction?

 

I'm keen to know how loud the Uh-Oh's were when Leica tried this with a WATE for the first time.

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[leicaleica]

Hey Mark,

 

Please define WATE ...

 

Wide Angle [ ... ]

 

Thanks.

[thisaccountisdeleted]

WATE ...

 

Wide Angle [ ... ]

 

Tri-Elmar

[marknorton]

WATE,,,

 

Yes, Wide Angle Tri-Elmar to distinguish it from the current one. Sorry, jargon I fell into using originally introduced I think by HC.

[erl]

Mark,

 

I have the 15mm CV, but my M8 just back to 'daddy.' However, my dealer indicated he may have a demo M8 to lend me and I think he also has a 55mm IR filter, which he would lend me. Question is, when I can get it from him. I will press the point with him to see what he can spare. Or, I just might have to buy a second M8 from his next shipment due in about a week.

 

Cheers,

Erl

[marknorton]

Thanks Erl. The thing is, Willem said this in the other thread:

 

"if i have time this week i'll post my cyan vignetting tests withte 15 and 12 mm heliars. they look horrible! also tested with behind-the-lens filtering. that gives a lot less vignetting but introduces an extreme focusing problem."

 

I'm wondering just how horrible and will the in-camera correction be able to sort it out?

[Guest magyarman]

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Corrected for this is very easy with use PTCorrect Radial Luminant. Take mabe 15 second no more. After finding out what is correct number for that one lens this number stay same forever that one lens, makes no differents what is apertur. Only trable that is, if no 6bit you must to remamber what lens makes every one foto, that is vary big job when is vary meny fotos. Bat is possible so is no reason against buy M8.

[lct]

Corrected for this is very easy with use PTCorrect Radial Luminant...

Do you mean that cyan shift caused by IR-cut filters can be adjusted by the Panorama Tool 'Radial Luminance'?

I tought it was just an anti-vignetting tool which compensates light fall off.

Did you use it to correct cyan shift as well?

[mjh]

Do you mean that cyan shift caused by IR-cut filters can be adjusted by the Panorama Tool 'Radial Luminance'?

I tought it was just an anti-vignetting tool which compensates light fall off.

Well, it is light fall off, only it is limited to the red channel – less red translates to more green and blue, thus the cyan corners. Radial Luminance can correct for vignetting for each colour channel independently, so it is the tool of choice here.