#67 New lensfun.xml for Sigma 30mm F1.4 DC DN | Contemporary
I'm new to pfotography but I just created my first lens correction using:
http://wilson.bronger.org/lens_calibration_tutorial/#id3
and
http://hugin.sourceforge.net/tutorials/calibration/en.shtml
The former site specifies I should send my lensfun.xml to the maintainers so here I am... It is a Sigma 30mm F1.4 DC DN | Contemporary 016 (EXIF data somehow comes up with the number 016 behind it). It is marketed as "Sigma 30mm F1.4 DC DN | C" or "Sigma 30mm F1.4 DC DN Contemporary".
The fotos used to come up with the corrections were shot on a Sony A6000 APS-C (1.5 crop factor) but this lens is also available in MFT.
Judging by the pictures after lens correction in darktable it look like it worked. Vignetting is unfortunately not possible for me to incorporate unless you guys have some good household tricks.
Discussion
It seems the chromatic aberration correction was still on when I took the pictures initially and I'm not sure it was incorporated in the RAWs. Distortion correction is off by default for this lens. Have done a second run with the corrections off. Take your pick ;)!
-- Edit
I just checked the TCA corrections on a few other images, it seems to not do anything?
Last edit: COMPUTERFREAKED 2016-09-08
Thank you for your efforts! There must be not more than one TCA entry. Moreover, for such small distortions, the poly3 model (only the b parameter) is probably better. I suggest you to upload one image which is suitable for TCA and distortion measurement to http://wilson.bronger.org/calibration. Thank you!
Last edit: Torsten Bronger 2016-09-30
No problem, I have just bought a second lens and when it arrives I will do this again.
I just uploaded a picture for the TCA correction. Refer to https://github.com/lensfun/lensfun/issues/112
Do you have any good tricks for creating the "milk glass" needed for the vignetting corrections since this seems to be a bit of an issue with this lens?
FYI I am currently using the following lensfun correction file, it has only 1 TCA correction line. Nevertheless I find it hard to judge if it actually does anything:
Last edit: COMPUTERFREAKED 2016-09-30
The diffuser may also be paper, possibly glued to glass because absolute evenness is paramount.
As promised I performed vignetting corrections for the lens. I used a milky plastic from the DIY store on a cloudy day. Judging by the corrected images it works very well :D
Attached is the lensfun XML file I currently use.
I have also done the corrections for the Sigma 19mm F2.8 and posted the lensfun XML here: https://sourceforge.net/p/lensfun/features/71/
Is it just a wired coincidence that "b" is zero?
The B being 0 is a coincidence. I have used other pictures to do distortion correction but all come up with a value very close to 0.
I assume the A6000 again? And do you by chance know whether this lens is also available for µ4/3?
Yes I shot the pictures with the A6000.
Apparently it is also available in MFT:
https://www.sigma-foto.de/objektive/30mm-f14-dc-dn-contemporary/technische-daten/
Okay, it is included. Thanks again!