Canon Camera lens

[CyberCowboy]

What's the difference between a USM lens and a non-USM lens?

Also, what is that term for the cropping that occurs in digital cameras vs 35mm? (i.e. the Canon digital Rebel has a 1.6x magnification factor or something)

 

[pyonir]

USM is Ultrasonic motor
1.6x crop factor

 

[CyberCowboy]

Does that mean it's quieter? what are the benefits?

 

[pyonir]

http://www.canon.com/technology/detail/device/usm/

 

[CyberCowboy]

OMG... i was looking for something like this on google, but didn't find it.
thanks.

 

[pyonir]

Originally posted by: CyberCowboy
OMG... i was looking for something like this on google, but didn't find it.
thanks.

Just had to type in ultrasonic motor. 😛

From experience, i can tell you that a USM lens is extremely quiet and very smooth.

 

[novon]

I have a sigma 18-200mm and it's noticably loud but not annoying. Kinda sounds cool actually, like a little robot sound. Are there any actual technical benefits to a USM?

 

[rahvin]

Originally posted by: novon
I have a sigma 18-200mm and it's noticably loud but not annoying. Kinda sounds cool actually, like a little robot sound. Are there any actual technical benefits to a USM?

Depending on what you are comparing it against, the lens could focus quicker.

 

[pyonir]

Originally posted by: novon
I have a sigma 18-200mm and it's noticably loud but not annoying. Kinda sounds cool actually, like a little robot sound. Are there any actual technical benefits to a USM?

From the linked article:

As a result, the ring USM needs no gears, provides quick start/stop response and control, and generates almost no noise.

I've noticed that a Canon USM lens has a bit of a faster auto-focus than my Sigma 70-200.