Hallöchen! Jonathan Niehof writes:
> In short, the attached snippet contains full (distortion + TCA + > vignetting) lens information for the Canon Powershot SD1100 IS/IXUS > 80. Thank you very much for the very thorough work! > Caveats: the distortion information is from the existing IXUS 80 > information in the database. I added TCA and vignetting data to the > IXUS 80 and copied it to the SD1100. But I think the old distortion data referred to JPEG imags, which may have seen already anti-distortion. Dos the data also work fpr DNG images? > This is the older database format since I'm still running lensfun > 0.2.8 (Ubuntu 15.10) and wanted to make sure it worked with my > current darktable. AFAICS, there is no difference between both Lensfun version in this case. > This camera doesn't have an adjustable aperture, but an ND8 > filter; when the filter is in, the camera reports the "effective" > aperture in the EXIF data, i.e. an aperture that would give the > same brightness. Do both cameras have that? > I'm assuming the ND filter doesn't affect the vignetting or TCA. If at all, it should be negligible. It may have a slight prism effect for the corners, but let's ignore that. > [...] > > I made a lenses.txt file with the distortion from the existing IXUS80 > in lensfun.xml, but with a changed first line: "Canon PowerShot SD1100 > IS: Canon, canonSD100IS, 5.9". I edited line 169 of calibrate.py to > default to "Canon PowerShot SD1100 IS" (matching the exif) instead of > "Standard". Matching the EXIF of the camera model or the lens model? Typically, the lens model field is empty for compact cameras. (I don't know for CHDK, though.) > For TCA, [...] > > I shot vignetting [...] Just to be sure: Both TCA and vignetting refer to DNGs, correct? > For the XML, I copied the IXUS 80 verbatim (both camera and lens), > then changed model tag to match Exif.Image.Model (which is the > same as Exif.Image.UniqueCameraModel), made the lang en a short > version, and named the mount similarly. I populated both the IXUS > 80 and the copied SD1100 lens calibration with the new TCA and > vignetting data. If both data is the same, I would give the SD1100 the IXUS 80 mount. This way, the first simply re-uses all calibrations for the second. > The vignetting already had two lines per focal length (near and > far distances); I added two more lines for smaller aperture, based > on the camera-reported effective aperture with the ND filter > in. Note that, as with the IXUS 80, the crop factor is 6.1 for the > camera and 5.9 for the lens (based perhaps on full area vs. JPEG > area?) Actually, bot must be the same Otherwise, your calibration data would not be applied accurately. Tschö, Torsten. -- Torsten Bronger Jabber ID: torsten.bron...@jabber.rwth-aachen.de ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape _______________________________________________ Lensfun-users mailing list Lensfun-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lensfun-users
