On Sat, 2013-03-09 at 12:30 +0100, Pascal de Bruijn wrote: > On Sat, Mar 9, 2013 at 12:56 AM, Leonard Evens > <[email protected]> wrote: > > I recently got a Nikon D800, and I am having problems with lens > > correction. > > > > I've used it with two lenses. > > > > It recognizes the 24-70 mm lens from the exif information, but it > > doesn't allow me to then select that lens, which, I've found, is > > necessary for lens correction to work. > > The lens isn't automatically selected? Possibly this happens because > of a naming mismatch between Exiv2 and Lensfun? Are you sure the 24-70 > available in Lensfun is actually the lens you have? Some lenses have > incompatible variations...
I'm not sure what you mean here. Let me explain again. Darktable will find the lens from the Exif information. But even when it does, it won't correct the distortion. I have to click on the lens in the darktable lens correction module. A menu comes up showing manufacturers. If I select the correct manufacturer, it gives me a list of possible lenses. If I then select the right lens, it proceeds to do the lens correction. This works for example with my Nikon D90, a Nikkor 18-200 mm lens and a Sigma 10-10 mm lens. If I don't go through the rather complicated procedure, the distortion correction is not done. It seems that although darktable has read the correct lens from the exif information, it doesn't actually know which lens it is until I do the extra work. For my new Nikon D800 and the Nikkor 24-70 mm lens, the lens information is correctly shown in the exif data shown in darktable. (Also exiv2 -pt image_name shows the lens description.) But when I click on it in the lens correction module, nothing happens. I am not given a list of manufacturers and an opportunity to select the right lens. This may be explained because although the camera model shows Nikon D800, read from the exif info, as shown by darktable, if I click on that, getting a list of manufacturers, if I choose Nikon. I get a list of models NOT including the D800. So although the exif info has told darktable the correct camera and lens, in reality, it recognizes neither. I presume the problem may be that the Lensfun database being used by my version of darktable doesn't know about the Nikon D800 or about the Nikor 24-70 mm lens. I have used Hugin in the past, and I suppose that if I work at it for several days I can figure out how to add the right information to Lensfun. But I am 79 years old, I am not going to live forever. I was hoping that someone else would deal with the issue. After all, darktable claims to support the Nikon D800, but apparently that is not really the case. The D800 has been around for several years and the 24-70 mm lens is a standard lens for it. I tried to include a NEF image from my camera and lens as an attachment, but it was too large. I will try to post it at a website I can use. > > Without a sample NEF there isn't much I can say for sure... > > > But it doesn't recognize the 70-200 mm, f/4, lens from the exif file > > although that information is in that file, giving the number 178 > > instead. So, in that case, lens correction also doesn't work. > > That means Exiv2 doesn't have the numeric lens ID in it's database yet. > > Or you using at least Exiv2 0.23? > > Or if you're using Ubuntu, are you using my Ubuntu-Release-Plus-PPA? > Which has a patched version of Exiv2 (0.23)? If so, please do report a > feature request to the Exiv2 project. > > I've previously wrote about this: > http://www.darktable.org/2012/10/whats-involved-with-adding-support-for-new-cameras/ > > Regards, > Pascal de Bruijn -- Leonard Evens [email protected] Professor Emeritus, Department of Mathematics, Northwestern University ------------------------------------------------------------------------------ Own the Future-Intel(R) Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 _______________________________________________ Darktable-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-users
