Developing my GFX files when using the GF 63 lens, I found an issue with ACR:
As mentioned before by other users, the GFX 'bakes' correction values for distortion, vignetting and CA into the raw files if used GF lenses. But the corrections are actually carried out by the raw developing software, in my case normally Adobe ACR. The files looked very fine ... mostly, apart some strange low frequency patterns in even areas towards the image corners.
To find out the origin of that behaviour, I compared three ways of raw conversions
1. conversion with Iridient X Transformer from raw to dng and w/o corrections of lens distortion, vignetting and CA + opening the dng in ACR and apply a certain set of fine tuning (color, contrast a.s.o.)
2. conversion with Iridient X Transformer from raw to dng and w/ corrections of lens distortion, vignetting and CA + opening the dng in ACR and apply a certain set of fine tuning (color, contrast a.s.o.)
3. directly open raw in ACR (w/ corrections of lens distortion, vignetting and CA automatically applied) and apply a certain set of fine tuning (color, contrast a.s.o.)
Findings:
Color, sharpness, appearance of the three files are very similar, that means Iridient does not modify the color of file in the conversion process which is good.
First file shows slight barrel distortion and slight vignetting (@ f2.8), but nothing serious. So I would not have a problem with the fact that the corrections normally are applied automatically by the raw developing software.
Second file is the fine, no issues.
Third file (plain ACR conversion) shows the side effect: The interpolation of the file data in order to apply the slight correction of distortion is not done properly but causes an ugly low frequency radial kind of Moiré pattern.
Did anybody else discover that effect?
Now I purchased the Iridient X Transformer: IMO an very useful and inexpensive tool, for the GFX files as well as anyhow for my other Fuji X-T1 raw files ;-)
PS
actually now I see that in the second sample file enclosed, which is the Iridient conversion w/ corrections (and which looks fine in full resolution: see the second of the crops), the enclosed file down sampled to 2000 pixel wide by PS CC again shows the pattern ... so maybe a more general problem of PS resampling files?
