On Sat, Mar 30, 2013 at 9:47 PM, Leonard Evens
<[email protected]>wrote:
> This is a continuation of other posts.
>
> I've found that darktable, at least the version I have, has some
> problems doing distortion control with my Nikon D800 NEF images and the
> 24-70 mm lens. Although it shows the exif data as seeing the camera and
> lens, the lens control module doesn't actually know about either the
> camera or the lens. (This may be a problem with the lensfun database.)
> What worked for my Nikon D90 with a Nikkor 18-200 mm and a Sigma 10-20
> mm lens doesn't work for the new camera.
>
Is this the issue described in the other thread? If so, we'd better address
it in that thread...
> But, as best I can tell, my D800 NEF images don't seem to need much, if
> any, distortion correction.
This is probably just because you're using a fairly expensive lens... So
these are designed to combat distortion as much as possible optically...
> I think I have auto corrections set in the
> camera. According to Thom Hogan's book, auto correction works for NEF
> images only when converted by Nikon software. Is darktable doing the
> same thing? If that is the case, I need not worry about the matter.
>
RAW formats are pretty much always (inherently) uncorrected, since the
Bayer pattern makes it difficult to do any kind of processing on it...
Whatever Nikon's software does is proprietary, but since Nikon also writes
the camera firmware, it's easy for them to make their software do the same
thing as the camera firmware.
> How does the camera do distortion correction?
>
No, clue this is Nikon proprietary... So nobody really knows...
I assume Nikon's firmware is just preloaded with correction data... This is
probably why firmware changelogs for many vendors list "Added support for
Lens X"... But this is just guesswork on my part...
Regards,
Pascal de Bruijn
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