# Does the Sigma USB dock work with multiple cameras?



## tianxiaozhang (Jun 13, 2014)

I got my 50Art and it works really well on the 5D3 but not so much for the 60D. Focus is off and it seems consistent. The camera store doesn't have any in stock and may not be able to get me another copy before my exchange/return time is up.

So as another alternative I could buy their USB dock and preset a focus preference on the lens.. 

And my question is:

Does the software allow me to set the lens differently for different camera bodies? Leave everything as-is for the 5D3 and change it to whatever it needs to be when it's mounted on the 60D?

Thanks!


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## YuengLinger (Jun 13, 2014)

Ok, this might be a good thread for me to admit I'm still totally confused by how the dock works.

If I have a camera with the AFMA function, why would I need the dock?

And with a camera like the 60D, how does the dock adjust for the body? Would I have to take a pic, check focus, remove lens, put on dock, adjust, and repeat until I get it right?

I have looked at a few "tutorials" online, but still don't understand.

Any pithy explanations would be great! ???


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## wsheldon (Jun 13, 2014)

The dock lets you program AFMA values directly into the lens with the added benefit of setting corrections for multiple distances, unlike the AFMA settings in the body. So if your Sigma is good at minimum focus distance but is off at longer distances you can program in multiple AFMA corrections, unlike body-based AFMA where you have to split the difference or just optimize at one extreme or the other. If you use the dock to perform AFMA you would typically disable in-camera AFMA for that lens (set it to 0).

The big down-side is that you can't currently set AFMA corrections for different bodies (addressing the OP's question), so you would either need to use body-only AFMA or a combination of lens and body AFMA in that scenario.

The other annoyance is that to use the dock for AFMA you have to shoot, unmount the lens, attach the dock, make adustments, remount the lens, re-shoot, and repeat. Pretty fiddly compared to using tethered shooting with the EOS Utility or Focal.

That said, the dock also allows you to update the firmware in the lens to correct performance or compatibility issues that are identified after shipping. For example, there was a firmware update for the 35 Art last year to improve AF reliability and noise. That feature of the dock could be important long-term if Canon tweaks their EF communication specs in future cameras, since 3rd-party companies have to reverse engineer those specs and things could break. I bought the dock for my 35A even though it doesn't need AFMA on my 6D, and it's been nice for the firmware updates alone and as an insurance policy. It's not expensive, but it would be a great item to share around with friends or a photography club since it generally sits unused after you tweak your lenses.

Hope that helps. I have the dock and software, so let me know if you need any specifics and I'll check tonight.


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## jdramirez (Jun 13, 2014)

I think you dock for the 60 d at different distances... then the 5d mkiii you use afma to bring it within speed.


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## Viggo (Jun 13, 2014)

Although you can't set afma for different bodies, you adjust the distances to work in tune with each other so even if you swap bodies , the relationship between the different distances is the same, you just do a in
Body afma to offset the whole range.

And you don't really have to mount try dismount repeat until it works. Measure up the first distance, for example 0.4m, then do afma there comparing to a live view focused or MF focused shot with AF and adjust in camera until it sticks. Take the in camera value and plot into the lens via docking at 0.4m.

Reset the afma in camera and measure out the next distance. That way you only dismount and plot in a value via docking once pr distance.


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## Hjalmarg1 (Jun 14, 2014)

wsheldon said:


> The dock lets you program AFMA values directly into the lens with the added benefit of setting corrections for multiple distances, unlike the AFMA settings in the body. So if your Sigma is good at minimum focus distance but is off at longer distances you can program in multiple AFMA corrections, unlike body-based AFMA where you have to split the difference or just optimize at one extreme or the other. If you use the dock to perform AFMA you would typically disable in-camera AFMA for that lens (set it to 0).
> 
> The big down-side is that you can't currently set AFMA corrections for different bodies (addressing the OP's question), so you would either need to use body-only AFMA or a combination of lens and body AFMA in that scenario.
> 
> ...


Thanks for this explanation. I was in the same dilemma.


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