PIX 2015

What about a 70-200 SAM?

Started Aug 29, 2009 | Discussions thread
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need "Real" USM/HSM to move Heavy Glass elements
In reply to redsim74, Aug 31, 2009

redsim74 wrote:

Could a SAM motor even shift the weight of glass in a 70-200/2.8 type lens?

redsim74 raise a Great Question. It is okay to used SAM motor on small & lightweight glass elements, but SAM would also labor harshly "trying" to move heavy glass elements = more miss shot. The end result of a 70-200 f/2.8 SAM would probably be equal or slower than a screw-drive Tamron 70-200 f/2.8.

Canon is also rather cheap in its implementation of USM motor in its standard zoom. But canon always uses real USM motor in its Telephoto/Super-Telephoto lens because USM offer the instant TORQUE required to moves these heavy glass elements.

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