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Good news on M9 + CV12 + CornerFix


sandymc

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Those that have been tracking the various discussions spread over a number of threads on the 18mm, CornerFix, etc, will know that there have been very inconsistent results from many wide angle lenses and the M9, and that CornerFix wasn't able to correct the images in all cases.

 

In short, in some situations the M9's internal corrections overcorrected, resulting the red edges. On these same images, while CornerFix could correct the vignetting in many cases, regardless of whether the lens was coded or not, it also occasionally also overcorrected badly in other images, for no obvious reason. This problem occurred on a number of lenses, but the CV12 was the worst offender.

 

The good news is that after a lot of e-mails and image analysis, we now have a version of CornerFix (1.3.0.2) that delivers consistent results. Particular thanks here to Eric Calderwood, who persevered through many image uploads, e-mails and a lot confusion.

 

This is an image, courtesy of Eric, using the CV12, first with in-camera correction as a WATE 16mm (where you can see some redness on the left), and then as corrected by CornerFix V1.3.0.2.

 

The new version of CornerFix is available in the usual place: CornerFix | Get CornerFix at SourceForge.net

 

Please note that this version of CornerFix has changed considerably since the last stable release; you should treat it as a beta release.

 

Please also note that the corners of lens such as the CV take a lot of correction, which increases noise in the corners considerably - this is inherent in any correction process, be it by CornerFix or in-camera. For example, on a lens that vignettes by four stops in the corners - not uncommon on the M9 - shooting at ISO640 and then correcting means ISO 2500 noise levels in the corners. So to whatever extent possible you should try to shoot at low ISO when using wide angle lenses on the M9

 

Sandy

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Sandy, you're a genius.

 

It is astounding the difference between the two images above, the "fixed" image above looks perfect.

 

Fantastic, many thanks for all of your hard work and kind words.

 

All the Best.

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Guest EarlBurrellPhoto

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This is very good news. 12mm being the only focal length obtainable with the M9 that can't be effected with an M8, now that it is usable there is a glimmer of support to the argument that being full-frame offers the M9 user an advantage at the wide end. Thanks, Sandy!

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This is very good news. 12mm being the only focal length obtainable with the M9 that can't be effected with an M8, now that it is usable there is a glimmer of support to the argument that being full-frame offers the M9 user an advantage at the wide end. Thanks, Sandy!

 

:confused:

 

I'm puzzled why you would say this about the M9's obvious advantage... What exactly would you use on the M8 when you need:

 

  • a 24 2.8
  • a 21 2.8

??

 

We won't even mention the really fast wide Luxes...which have no equivalence on the M8.

 

Though of course you need the Luxes on the m8--they're your only option for a fast 28mm or a 35 (ish) 1.4 equivalent FOV...

 

@ Sandy, this is indeed good news! Nicely done!

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Guest EarlBurrellPhoto
:confused:

 

I'm puzzled why you would say this about the M9's obvious advantage... What exactly would you use on the M8 when you need:

 

  • a 24 2.8
  • a 21 2.8

??

 

We won't even mention the really fast wide Luxes...which have no equivalence on the M8.

 

Though of course you need the Luxes on the m8--they're your only option for a fast 28mm or a 35 (ish) 1.4 equivalent FOV...

 

 

Sorry if my statement was easy to misunderstand. I was speaking strictly about FOV. You are correct that faster lenses do have a particular attraction with the M8 (and M9) However as I've mentioned elsewhere, I find that the shallow DOF of even those ultrawides at f/1.4-2.8 mitigates their usefulness compensating for the high-ISO performance limits. Typically I find myself stopping down my fastest wide, the 21 Elmarit, to f/4 and 5.6.

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