To recap, the previous post showed images of the Tim Ashley's 18mm f/3.8 as corrected by the M9's in-camera correction firmware. The result was a red tint on one edge. I also mentioned that the then current version of CornerFix couldn't do much with the problem, because V1.2 of CornerFix couldn't deal with optical decentering.
However, V1.3.0.0 can. Here's the result, first correcting the 18mm f/3.8 for an original image for which coding was disabled (so no in-camera corrections):
18mm f/3.8 uncoded with CornerFix 1.3.0.0 correction
18mm f/3.8 coded as "Auto" with additional CornerFix 1.3.0.0 correction
And now if we use CornerFix to correct the nasty in-camera corrections that gave a red edge:
18mm f/3.8 coded as "Auto" with additional CornerFix 1.3.0.0 correction
Both of those are (IMHO) pretty good - they show no visible signs of red edges anywhere. However, I do recommend that if you are going to use CornerFix, you shoot with lens detection disabled, aka with the lens uncoded. The reason is that if you have a camera/lens combination that shows the decentering issue (and every M9 image I've analyzed regardless of lens shows it) and use your lens coded, a interference pattern can form between the actual vignetting and the in-camera correction. Think about two circles, on top of each other, the same size, but with their centers slightly offset as shown below:
Interference between offset circles
Where the circles come together, you get e.g., over-correction, and where they are far apart, under-correction, in a complex two dimensional pattern. And that pattern is unfortunately nearly impossible to correct; there is no way to tell the difference between what should be there and what shouldn't. That may or may not occur in your case, but the easy way to avoid it is not to use in-camera corrections when you're planning to use CornerFix.
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