On Mon, 31 Dec 2018 at 21:42, Jean Bruenn via Lensfun-users < lensfun-users@lists.sourceforge.net> wrote:
> Hi there, > > I am pretty new to photography (or rather very new to raw-processing) > though aware of the lensfun library for quiet some time now. Anyway, I > recently bought a Sony Alpha 6300 (also named ILCE-6300) with a Kit-Lens > which is found in lensfun as: Sony, E 16-50mm f/3.5-5.6 OSS PZ. Today when > comparing the JPEG produced by my camera with the lensfun-corrected RAW > result I noticed quite different results and I'm wondering if you're > interested in my observations and if the lens-correction is doing something > wrong. > > Vignetting > > At 16mm and 17mm the Lens has pretty strong vignetting. You can see that > here: https://jeanbruenn.info/lf_original.jpg and here: > > At 18mm the "strong" vignetting disappears. > > However, as soon as I do apply lens-correction (I do use darktable for > that) I believe (it's difficult to spot/see on my screen and it's mostly > noticable on thumbnails) that there is some sort of "light" vignetting as > soon as I do apply the lens correction. Take the following downsized photo > for example (https://jeanbruenn.info/thumb.jpg), all four corners show a > white dust/mist just like in a vignette-effect. You'll get it more visible > if you open that photo and play around with the contrast slider so that the > white from the borders is increased: The same in the following two Pictures > (uncorrected: https://jeanbruenn.info/lf_original2.jpg, corrected: > https://jeanbruenn.info/light_vignette.jpg) > > I've encountered the same issue with viginetting on the same lens (using the a6000) and also on the 55-210 kit lens. See https://discuss.pixls.us/t/lensfun-vignetting-correction-for-sony-kit-lenses/9537 i've worked around it by using using an LCP. However it is not perfect as only lensfun 0.3.95 supports the adobe correction model, and hence it can't be used properly with darktable. Cropfactor > > This made me check the JPEG of the camera and compare it with the > lens-corrected RAW one. At first I've been pretty much impressed: > > JPEG from my Camera: 6000x3376 > > RAW lensfun corrected: 6048x4024 > > Which means the camera (is probably aware of the issues with the lens and) > crops a massive amount of 648px in width and 48px in height. However. This > might as well be some sort of misconfiguration of me (since I told my > camera to take photos in 16:9 when I took those photos - Going to check > with the 3:2 setting later / tomorrow). > > Your JPEGs from camera should be 6000x4000. 6000x3376 is 16:9 ratio (with no additional cropping). Fixing the vignetting correction for the 16-50 and 55-210 lenses in a "native" lensfun way would be really great. Unfortunately, it seems that while I can do distortion calibration i lack the gear needed for vignetting correction. Thanks, Guy
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