Dear list,
I don't know much about lensfun, but I can confirm that in my setup
(lensfun 0.3.2-6 package as supplied by Arch Linux, darktable built
manually from the current darktable-2.4.x branch) the lens correction
module actually fails to select the right settings for this picture
(Nikon AF-S VR Zoom-Nikkor 70-200mm f/2.8G IF-ED on a Nikon D750).
I quickly hacked a couple of printf()'s into src/iop/lens.c and it looks
like lf_db_find_lenses_hd() is called with the right arguments, but
fails to return a result.
I've noticed two things.
First: lenstool recognizes this lens as an APS-C lens, but as far as I
can tell it is a full-frame lens?
$ lenstool -L "Nikon AF-S VR Zoom-Nikkor 70-200mm f/2.8G IF-ED"
Matching lens found in the database:
Nikon / Nikkor AF-S 70-200mm f/2.8G VR IF-ED
|- Crop factor: 1,528
|- Aspect ratio: 1,5
|- Focal: 70-200mm
|- Min-Aperture: f/2,8
|- Center: 0,0
|- Compatible mounts: Nikon F AF,
|- Calibration data: tca, vign, dist,
Second: The other lenses Mark mentioned also seem to be marked as APS-C
lenses in the lensfun database, but actually seem to be full frame
lenses. There are only a few APS-C lenses listed in the drop down, e.g.
the Nikon AF-S DX Nikkor 35mm f/1.8G, but that's because this lens
actually has two entries in the Nikon database (one for crop factor
1,528 and one for crop factor 1).
Does this maybe point to the root cause?
cheers,
Simon
On 23.04.2018 14:43, Mark Feit wrote:
> On 04/23/2018 03:26 AM, sturmflut wrote:
>> Could it maybe be possible that the lensfun database got corrupted on
>> some systems?
>
> It's not just some systems and it's not a database problem. I've had
> this problem for a long time and, figuring it was pilot error, never got
> around to digging around to find the cause.
>
> The DT I run (2.4.1 on Linux; I will be upgrading later this spring when
> I get a lull in shooting) is built from the sources against the lensfun
> installed on the system, which I update (binaries and data) before
> building. That leaves no chance of a version mismatch.
>
> DT correctly identifies the body and lens in the image information box.
> The Lens Correction tool correctly recognizes my bodies (SLR and
> point-and-shoot) but fails to recognize any of the lenses I use regularly:
>
> Nikkor AF 18-35mm f/3.5-4.5D IF-ED
> Nikkor AF-S 28-300mm f/3.5-5.6G ED VR
> Nikkor AF 35-70mm f/2.8D
> Nikkor AF 50mm f/1.4D
> Nikkor AF-S 70-200mm f/2.8G VR IF-ED
>
> I've checked the XML files that make up the Lensfun database, and all
> are in there. I also have and use a 28-105 which is not in the database
> and, as expected, isn't found and behaves the same way.
>
> One other thing I've noticed is that the list of choices available when
> trying to select a lens manually is a subset of what's in the database.
> The brands with a compatible mount show up (so I get Nikon, Tamron and
> Samyang but not Canon or Olympus), but the list of lenses is incomplete
> despite being in the XML. Whether this is a problem in Lensfun or DT
> remains to be seen, but I'd be hard-pressed to believe that a Lensfun
> failure to recognize common lenses like the 70-200 or the 50 f/1.4 would
> have been left to fester for very long.
>
> An image that illustrates the problem on my system can be downloaded
> from https://s3.wasabisys.com/darktable/lensfun.nef.
>
> --Mark
>
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