Quote Originally Posted by Tannin View Post
..... I fair dinkum don't get it.
firmware!

As manufacturers introduce newer cameras in the future, and some have been known to introduce some incompatibilities with 3rd party gear .. the owner now has a way to upload any fixes via firmware fixes themselves rather than going through the hassle of getting the gear back to the service centre for what is in effect a very simple fix.

It wasn't all that long ago that Nikon introduced a firmware update for a recent camera which stuffed compatibility with some Sigma lenses. Up to this new firmware the lenses worked fine, but the firmware update killed that. Sigma has a firmware update service to fix the incompatibility issues which is free, but not all their lenses can be updated via firmware too.
Those lenses that are compatible with the USB dock didn't require a trip back to the service centre, the firmware was downloaded locally and uploaded to the lens by the user in the comfort of their own home.
I vaguely remember a problem with some Sigma lenses relating to a Canon camera body too, many years back too.

The focus tweaking features are a bonus I guess!
Also note that the Sigma software also allows for tweaking the speed of focusing(not just the accuracy) for certain lenses to suit a particular purpose or style of useage.

I'll actually go further and say that I think the software could be even better, that is it's currently limited in what it should be able to do.
Many(if not all) fast lenses suffer from focus shift as you stop the lens down. This could easily be accounted for by software like this, where you may have an option to set focus distance tweaks on the basis of aperture value set.
So hopefully Sigma has the ability to further improve the software used with the dock.

Overall tho, the point is that the USB dock is an optional accessory that the user has the option of buying or not. It's not compulsory for the lens to work properly.
It doesn't come with the lens, so it's not forced upon you in any way, but if you're having issues a specific lens, this is simply a way to account for it without the need to go through the problem of sending a lens back to have it tweaked or re set, or whatever.


I actually think that manufacturers of camera bodies should allow the ability to tune lens parameters from within the camera body itself.
I'd rather see this focus tuning/tweaking thing all done in camera, in real time whilst the lens is attached to the camera and via a computer of some sort(tablet/laptop/phone/whatever).
I would be nicer to have the ability to tune focus for a certain lens based on specific AF points(or areas) on the sensor, which could take into account various optical issues for lenses or troublesome af points in cameras.(note that there are some mirrorless cameras that allow this degree of fine tuning too! .. Olympus OMD-M1 comes to mind for some reason)

AF fine tune is all well and good up to a point, but it is severely limited in what it can do.