lens codes

macca

macca

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Name
Iain
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hey guys,

on a lens you get a code ism for image stablisation. what do hsm and usm stand for?
 
ultra sonic motor
 
I think usm is Ultrasonic Motor (Canon)and hsm is Hyper sonic motor (Sigma)
 
thanx guys :D any idea what they do? is it anything like image stabilisation? im looking at a wide angle canon 10-22 or sigma 10-20 and dont want shaky pics lol
 
Its the method used to focus - USM is an ultra sonic motor - as mentioned earlier. Essentially it is near-silent and drives the focussing gear by ossilating a toothed ring. HSM is similar in technology and approach. If you have a non USM or HSM lens, just listen to the whine and whirr in comparison ;)
 
They are the focus motors usually makes for fast, quiet and smooth focus.
 
thanx guys, love the detail, very helpful :D

any idea if i can get a sigma 10-20 or canon 10-22 in ism?
 
not as of now. Bear in mind that IS is useful after you can no longer balance shutter speed against focal length. A good rule of thumb is to keep shutter speed one stop higher than focal length. For 10mm, you only need to shoot faster than a 10th of a second for a crisp image. This is an extreme example - you'd want to be at around a 100th for a REALLY crisp image without a tripod.... but the argument is, with a wide angle lens, image stabilisation is not of as much use as it is after normal focal lengths (50mm to 70mm)
 
thanks for the info jonny, will stop looking for an ism lens haha wanted 1 as my 17-85 and 100-400 lenses are both ism but no big deal. i will have to get a lens and just test it out to get what i want. thanx again guys
 
Feel better?
 
Also bear in mind that there are two types of USM, the "standard" variety and the ring-type USM which is even quieter.
 
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