USM vs HSM

So apples to apples, assuming both lenses are calibrated correctly - are there any major differences between HSM and USM? Is the AF just as fast and accurate? I'm trying to decide between the Canon 17-55 and Sigma 17-50.. wondering if the $500 is worth it seems IQ similar and build is even better on the Sigma.

HSM and USM are the same thing. One manufacturer calls it one thing and one calles it another. Sigma calls thiers OS.

Correct me if I am wrong...

bucket772 wrote in post #12985204
HSM and USM are the same thing. One manufacturer calls it one thing and one calles it another. Sigma calls thiers OS.

Correct me if I am wrong...

AF:
USM (Ultra-sonic motor) = Canon, HSM (Hyper-sonic motor) = Sigma, USD (Ultra-sonic drive) = Tamron.

Stabilization:
IS = Canon, OS = Sigma, VC = Tamron.

And as always there are big differenes even within lineups. Some Canon USM lenses seem markedly peppier and smooth than others. Same with Sigma. (Tamron only has one USD lens so far, so hard to say there)

I have Canon lenses with USM and Sigma lenses with HSM. The Canon lenses are a little faster, but you have to compare them directly to notice a difference. I've never found myself thinking that any of my HSM lenses were focusing too slowly when using them under normal shooting conditions.

jackerin wrote in post #12985581
AF:
USM (Ultra-sonic motor) = Canon, HSM (Hyper-sonic motor) = Sigma, USD (Ultra-sonic drive) = Tamron.

Stabilization:
IS = Canon, OS = Sigma, VC = Tamron.

I realized my error after I hit send. Here in the east we just had a mild earthquake. I was a little distracted. Thanks for pointing my error out

AF speed doesn't just depend on the type of the motor, but also on how much glass it has to move, and how far. I am sure the weight of the glass to move, and the travel distance are not identical in the two lenses in question (Canon 17-55 and Sigma 17-50).

I haven't owned the Canon, only the Sigma. For me, it focuses fast enough (much better than my previous zoom, Tamron 17-50).

I have used both Sigmas HSM and Canon's USM and noth are very good, but Canon's seems to be a tiny bit faster, but much quieter. I was dissapointed with HSM at all, specially with the price difference.

I've tried Sigma's HSM and Canon's USM, and honestly, in everyday shooting conditions, you're not going to notice any difference. Both are terrific.

Just like Canon makes Ring Type USM and Micro Motor USM, Sigma also makes TWO types of HSM. If you have a Sigma lens with a rotating focus ring and no focus distance window (Sigma 17-50, 17-70, etc) it is not the equal of Canon's Ring Type USM. (lacks FTM for example)(also slightly slower and noiser)

Other Sigma's like the 30mm, 50mm, 50-150mm, 70-200mm, etc., do have an excellent version of HSM and it is pretty much equal to Canon's USM.

I have no experience with Tamron's USD, so I can't comment.

Here are some videos so you can see and hear the difference:

Sigma 17-50 HSM

http://www.youtube.com …osmrXBFm8&featu​re=related

http://www.youtube.com​/watch?v=F14IXyqs8jw&N​R=1


VS....


Canon 17-55 USM:

http://www.youtube.com​/watch?v=VKxCzOYGWyU

http://www.youtube.com​/watch?v=IBlzJx9h2TA