Attached is the xml file for a Tokina AT-X 24-70mm f/2.8 PRO FX calibrated on a Nikon D810. It includes distortion and TCA but not vignetting.
I recently bought this lens to replace a AF-S Nikkor 24-70mm f/2.8G ED for my landscape photography as it has much better edge resolution, but instantly found not having a lens profile in Darktable was a real problem. I had to use the 'nearest' lens profile I could find that produced 'reasonable' results but nearly always left TCA fringing at wide angles that I couldn't get rid of and which negated the improved resolution of the lens. But now thanks to all the Lensfun people I am extremely happy with the resulting images.
I found the post-shooting parts of the calibration process the more difficult. Getting to grips with operating Hugin for the first time was a trial due to the GUI version differences between my installation and those in the tutorial videos. Setting-up the control points on each image and cutting and pasting each distortion correction from Hugin into the text editor was a slow process, but not difficult once I got the hang of it. I found using a 150% zoom instead of 200% on the control points tab as advised in the tutorial video, was easier as fewer points were needed yet the calibration results were the same (although this may have something to do with my specific images).
I originally tried to use Andreas Schneider's python scripts followig his excellent tutorial, but couldn't install all the required Python libraries on Linux Mint (I'm not familiar with Python and its environmental needs in my flavour of Linux) and as time was dripping away I decided to try Torsten's script. That script worked and quickly produced a set of tifs for Hugin, although how to run the TCA calculations after Hugin distortionhad me worried I'd missed something and I spent a while re-googling. Fortunately, the script is intelligent enough to work out from directory contents which step of the process is next and re-running it quickly produced the TCA calibrations and the output xml - everything that was needed! I mean no complaint, as Torsten and Andreas have obviously spent (and continue to spend) a huge amount of their time developing, maintaining and supporting their scripts for free, for which I, and I'm sure many others are eternally grateful.
Installing the xml file on Linux Mint so Darktable could use it was fraught, mainly because it took quite a time for me to find out that lensfun version upgrades can exist in 3 different places on my system, and that each is timestamped with when it was created, and there is lensfun coding logic that chooses which version to load based on the youngest timestamp (I think). Info on the Lensfun website as to how lensfun installation/update works was invaluable but I still spent a long time puzzling why Darktable wasn't seeing my new xml in /usr/share/lensfun/version_1. Once I had found and recorded where each instance of lensfun data was on my system, its timestamp, and if it contained my calibration file, it turned out it was using the one in /var/lib/lensfun-updates/version_1 which of course didn't include my new calibration file! Adding the file into this location and changing the timestamp made everything work. Complicated - but I understand it is catering for coexistence of different lensfun versions.
Once again thanks to everyone involved in Lensfun - you provide a very important service.
On 29/04/2020 21:26, Graeme Leese
wrote:
Hi,
After following the tutorial you should have a lensfun.xml file created for your new calibration. If you email that file to the list then I can add it to the database for you.
Thanks,Graeme
On Wed, 29 Apr 2020 at 19:28, Dusenberg <dusenb...@gmx.co.uk> wrote:
Hi all,_______________________________________________
Just joined this list and want to submit a lens calibration I recently made using Torsten Bronger's tutorial that isn't in the lensfun database. I thought I read that it can be done through here but how? Anyone know?
Thanks
Lensfun-users mailing list
Lensfun-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/lensfun-users
<lensdatabase>
<lens>
<!-- Calibrated on Nikon D810 by Julian Rowntree, April 2020 -->
<maker>Tokina</maker>
<model>Tokina AT-X 24-70mm f/2.8 PRO FX</model>
<mount>Nikon F AF</mount>
<cropfactor>1</cropfactor>
<calibration>
<distortion model="ptlens" focal="24" a="0.03628" b="-0.10484" c="0.0626"/>
<distortion model="ptlens" focal="26" a="0.03281" b="-0.09514" c="0.0565"/>
<distortion model="ptlens" focal="28" a="0.02394" b="-0.06904" c="0.03838"/>
<distortion model="ptlens" focal="30" a="0.01955" b="-0.05947" c="0.03836"/>
<distortion model="ptlens" focal="32" a="0.01342" b="-0.0386" c="0.01668"/>
<distortion model="ptlens" focal="35" a="0.00564" b="-0.01287" c="-0.00876"/>
<distortion model="ptlens" focal="40" a="0.00061" b="0.0047" c="-0.01211"/>
<distortion model="ptlens" focal="50" a="0.01557" b="-0.05414" c="0.07745"/>
<distortion model="ptlens" focal="60" a="0.00979" b="-0.0296" c="0.04857"/>
<distortion model="ptlens" focal="70" a="0.01958" b="-0.06696" c="0.09575"/>
<tca model="poly3" focal="24" vr="1.0001977" vb="1.0000667"/>
<tca model="poly3" focal="26" vr="1.0002076" vb="1.0000659"/>
<tca model="poly3" focal="27" vr="1.0002033" vb="1.0000514"/>
<tca model="poly3" focal="28" vr="1.0002207" vb="1.0000593"/>
<tca model="poly3" focal="30" vr="1.0002147" vb="1.0000375"/>
<tca model="poly3" focal="32" vr="1.0001762" vb="1.0000449"/>
<tca model="poly3" focal="35" vr="1.0001308" vb="1.0001005"/>
<tca model="poly3" focal="40" vr="1.0001047" vb="1.0000220"/>
<tca model="poly3" focal="50" vr="0.9999695" vb="1.0000309"/>
<tca model="poly3" focal="60" vr="0.9999448" vb="0.9998926"/>
<tca model="poly3" focal="70" vr="0.9999201" vb="0.9997762"/>
</calibration>
</lens></lensdatabase>
_______________________________________________ Lensfun-users mailing list Lensfun-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lensfun-users
