Originally posted by rawr Lens dock adjustments don't really help much, since the problem is deeper.
There are hundreds of thousands Sigma lens users who do not have AF issues.
Sigma produce so many lenses for various mounts they can even afford to drop a mount (K-mount) from their programme.
I'm not denying that there are Sigma lenses with AF issues, but there are genuine Pentax lenses with AF issues as well. I'm not saying that Sigma do not produce more lenses with AF issues (for whatever reasons) but the idea that there is a deep problem with every single Sigma lens has absolutely no merit at all
Originally posted by rawr Sigma really do need to go through their lens firmware with a fine tooth comb, particularly the AF code sections.
According to everything I know about AF systems -- I've read white papers, patents, etc. -- there is no "
AF code" in a K-mount lens' firmware. HSM lenses may contain a controller that enacts the requests made by a camera, but the responsibility to obtain AF focus is solely the camera's and the latter also determines in what way that objective is achieved.
Please point us to a reliable source, if you know anything to the contrary.
Again, I'm not saying that there are no Sigma lenses that require calibration. It is even possible that Sigma have released batches of lenses that feature incorrect lens parameters; I have no knowledge of that but it is a possibility and could explain the 18-35/1.8 phenomenon (a lens that works fine for many but caused issues for some).
In any event, it seems rather safe to exclude the possibility that Sigma has to attend to some "
AF code" in their lenses.
Back on topic:
It seems that K-1 allows downgrading the firmware version as well as upgrading it. Member lennyl has made a respective remark in the
comments section of the V1.40 firmware release announcement. That would be fantastic news, AFAIC, if it could be confirmed.
Did anyone other than lennyl observe a shift in AF adjustment values after the update to V1.40? It is not the first time someone reports that AF adjustment values have to be changed after a firmware update. Often, I think, such observations can be chalked up to changing conditions (e.g., changing the distance to the focus chart) when performing the AF adjustments, but lennyl seemed to have been rather systematic about this and even reported more AF hesitation ("hunting") with V1.40. I'm still sceptical that V1.40 brought any changes to the AF system, but it is of course possible.