Cyan corners

[Peter Branch]

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Can anyone explain please how will the M8, in its uprated version, knows if an IR/UV filter has been used on wide angle lenses?

 

I understand that it can only apply the cyan corner correction for lenses in the range 16 to 35mm focal length if it reads a coded lens - that is obvious - but it is not nearly so obvious how it knows if a filter is attached.

[j. borger]

I can only guess .... but there is now an option in the menu to set lenscoding on and off ..... splitting the "on" category in 2 could do!

[johnll]

I imagine it would also be possible to create a graduated circular mask for use in PP to handle this issue, for those with non-coded / non-Leica lenses.

[marknorton]

There has to be some manual method of specifying it, can't see that they could tell from the image alone because there may be no red content in the image at all to recognise the characteristic pattern

 

I assume that with a knowledge of the lens and that there's a filter in use, they will scale the red channel for each pixel according to how off the lens axis it is. The profile of scale factor against displacement from the axis will be different for each lens.