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01/25/2005 03:43:15 PM · #1 |
| I know that USM stands for Ultrasonic Motor (in relation to lenses anyway) but I guess I'm not especially clear on what that means. How much better is a USM lens than a non usm? |
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01/25/2005 03:48:04 PM · #2 |
You can HEAR the difference :-)
The USM lenses are wayyyyyy quieter. The cheapy canon 28-105 USM doesn't make a peep, compared to my cheapy (yet better) 50mm F1.8 which sometimes can sound like a freight train when focusing. |
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01/25/2005 03:49:44 PM · #3 |
| Ya with the "BUZZ WHIR" of my 50 f1.8 II and the loud "CLACK" of the 20d mirror I am quite the loud photographer. =) |
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01/25/2005 03:50:12 PM · #4 |
| From what I have read a lot depends on which lens you are talking about. The USM lenses are quieter and should be faster at focusing. But just how much better they are depends on which non-USM lens you are comparing them to, there is a huge variation in both the speed and noise a non-USM lens makes with focusing. You can also do a manual focus with most USM lenses without switching the little mode switch. |
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01/25/2005 04:00:20 PM · #5 |
Originally posted by scottwilson:
You can also do a manual focus with most USM lenses without switching the little mode switch. |
That's very true. And I'll admit, I only figured that out a few weeks ago. |
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01/25/2005 04:04:46 PM · #6 |
Some people actually think that USM makes their photos sharper! Can you imagine that? :)
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01/25/2005 04:07:55 PM · #7 |
Originally posted by micknewton:
Some people actually think that USM makes their photos sharper! Can you imagine that? :) |
Oh Damn! That's another dream shattered!
Next you'll tell me you have to remove the lens cap??? |
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01/25/2005 04:09:58 PM · #8 |
I have a 35mm f/2.0 that is non-USM and buzzes like crazy. The best is when the 10D cannot find focus and the lens runs back and forth searching for it... cracks me up, and anybody standing near by.
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01/25/2005 06:04:49 PM · #9 |
The biggest thing about some USM Lens is that you can manual focus without switching from automatic. You just focus manually and it overrides the automatic.
This works great for a lens that wanders you can help it focus on a general point and then let the auto take over. This greatly reduces the wandering of some lenses.
Message edited by author 2005-01-25 18:05:27. |
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