On Thu, Dec 8, 2016 at 9:28 AM, <junkyardspar...@yepmail.net> wrote: > I've made two attempts at creating a vignetting correction profile for a wide > lens (Olympus 12/2) and both times ended up with overcorrection when testing > on real-world images. I didn't have this issue when calibrating the 25/1.8, > and wonder:
> is the use of a flat diffuser over the lens face an inherently flawed method > with lenses that cave substantial curvature to the front element? I *think* so. > It occurs to me that the distance between element and diffuser is probably > twice as much at the edges as at the center. On an opaque object this would > obviously result in signifcantly reduced light at the edges, but I don't > understand optics well enough to know if this is relevant to the image > projected on the sensor through a bunch of glass... > If this is indeed the problem, is there a suggested workaround? I was > thinking of taking the shots of the inside of a softbox or something similar, > to increase the distance between diffuser and lens. I would try to shoot panorama with significant overlap (50%?), and then use hugin to assemble it. This does result in vignetting correction. Unless hugin changed their vignetting correction algo from lensfun's, the result can be directly re-used in lensfun. At least that is what bronger suggested for calibrating some wide-angle prime with curved front element. > Thanks, > > jys Roman. > ------------------------------------------------------------------------------ > Developer Access Program for Intel Xeon Phi Processors > Access to Intel Xeon Phi processor-based developer platforms. > With one year of Intel Parallel Studio XE. > Training and support from Colfax. > Order your platform today.http://sdm.link/xeonphi > _______________________________________________ > Lensfun-users mailing list > Lensfun-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/lensfun-users ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today.http://sdm.link/xeonphi _______________________________________________ Lensfun-users mailing list Lensfun-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lensfun-users
