For almost 2 years now I have been struggling with the inadequacies of the ingenious Sigma 24mm 3.5 c from the “I series”.
It has a very short shooting distance, which I also use intensively for a documentation in a film archive.
Correcting the distortion is a difficult and tiresome task.
Are there any other fellow sufferers among you who would like a DxO module for this beautiful 24er?
I own the Sigma 24/2 i which also has some distortions but although “younger” it got a DxO profile, I believe?
My take for myself: Buying a lens which gets “zero distortion” only by the help of software has a massive drawback when using a RAW converter which can’t / isn’t allowed to read the inbuilt manufacturer’s lens profile (I mean the one affected by lens firmware update). Most of DxO’s profiles are great, few less so.
I think I can’t complain at DxO. They do the profiles in their way, in their (non-transparent) priority-list, some come quicker, others like yours need years. That has been my reason to go back to a RAW converter able to read the manufacturer’s profile, the waiting was too long. Again, it was not DxO deciding to design a lens in need of SW correction. It was my decision to buy it, nonetheless.
I know it’s not helpful for your request, I’m sorry.
EDIT: Just saw the minimum focus distance. Wow, 10.8 cm is really super close. But then, I would not hold my breath if I were you: In my experience lens distortions are corrected when focused at infinity. I have some lenses which become worse (in terms of distortion) the closer I get. So, even if DxO would provide a lens profile one day, there’s a possibility of disappointment at close range. Just saying - not knowing!
DxO’s modules include corrections for different distance settings. They can be adjusted manually, if the image file does not provide focusing distance information. Changing the distance and focal length (in case of zoom lenses) can make quite a difference.
I watched some reviews of the lens from Gordon Laing and Dustin Abbott. The close minimal focus distance includes (at least wide open) very soft areas outside the image center - which can be a nice effect, but apparently there’s no focus plane, but more of a focus “sphere”. I could imagine that even when DxO releases an optical module, a couple of customers will complain about that soft outer areas.
Not an easy task to profile this lens.
Field curvature can be quite an issue. Manufacturers don’t advertise it and if it’s strong, it can’t really be compensated for.
I see a lot of field curvature on a couple of my manual focus prime lenses. Interestingly, the effects of a particular lens’ field curvature may not be linear. It could be very sharp in the center, somewhat sharp in the corners but much less sharp in between.
For my lenses stopping down doesn’t improve the issue but actually makes it worse. However, this phenomenon in my lenses is much more visible at relatively close shooting distances with the subject no more than 8 or 10 feet away. In normal outdoor shooting distances I see little to no obvious effects of the field curvature. One of these lenses, my Voigtlander 35mm f/1,2 Nokton, becomes quite usable at all apertures when I use it for that purpose.
…which could be a sign of focus shift, another good friend of the photographer