Purple flare: Causes and remedies

Started Mar 1, 2013 | Discussions thread
Detail Man
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Re: Purple flare: Causes and remedies
In reply to Anders W, Mar 2, 2013

Anders W wrote:

Detail Man wrote:

So, I wonder if the slight shifts in the Magenta bias (of DxO Optics Pro 7.23's WB controls) to the GH2's (Auto WB) "As Shot" WB image-file meta-data ... from +2 towards Magenta to Zero Tint being sufficient, and with +2 towards Magenta to -2 towards Green being more than sufficient ... seeming to kill the slight purple tinting that exists is dealing with the above imbalance aspect described ...

... and the Panasonic M43 sensor optical characteristics have less of the "pollution" effects described.

Newer GH2 RAW processed shots: http://forums.dpreview.com/forums/post/50699358

GH2 RAW processed shots and OOC JPG: http://forums.dpreview.com/forums/post/50699473

I don't know the tint scale DxO Optics Pro, but on the LR scale (-150 to +150), a couple of units is nothing.

It ranges from -100 to +100, but I have found that Lightroom 3.x usually ends up with tint biases on the order of 10 times the numerical value of DxO's WB Tint from the same image-file meta-data ... so the scale-factor must be significantly different between the two applications.

In order to correctly white balance the shot I produced with my purple filter (CC70M + CC30M + 80A), I had to, not surprisingly, produce a new profile by means of Adobe's DNG Profile Editor. The latitude provided by the ordinary tint ant temp scales did not suffice.

As to the GH2, you might have seen that we now have evidence from a side-by-side comparison with the E-M5 that conclusively proves, to my mind, that the GH2 is in the same camp as the G1, i.e., essentially free from the purple disease. See here:

http://forums.dpreview.com/forums/post/50854356

What I saw (with the straight-on incandescent lamp) was not a whole lot, anyway. Nice to know.

Since the samples that you reference are from a G5, one would have to assume that there have been no changes in the optical micro-lenses and filters covering the photo-sites on the presumably otherwise common image-sensor assembly (that the GH2 uses). Hopefully so.

Note: Have now seen your post-edit - which adds the same proviso that I have above ...

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