Beginner Looking to know about a sigma HSM lens

shannensdaddy

shannensdaddy

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Hi
I am looking for advice .
SIGMA 17-70MM F/2.8-4 DC OS HSM MACRO - NIKON FIT what,s the difference between the HSM and non hsm version , Will the non version autofocus on the Nikon D90 ..
I know the ( HSM) Hyper Sonic Motor for fast focus but is this option not the same that is inbuilt in the D90


regards
 
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Any Sigma lens with HSM in the title means the AF motor is in the lens itself. If it doesn't have that in the title then it is likely that it requires the AF motor in the camera body and uses a screw drive. In both cases your D90 will be fine as it has an in body motor. Think of HSM as equivalent to Nikon AF-S and non HSM as AF-D/AF Nikon lenses.
 
shannensdaddy said:
Will the non version autofocus on the Nikon D90
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Yes.
shannensdaddy said:
I know the ( HSM) Hyper Sonic Motor for fast focus but is this option not the same that is inbuilt in the D90
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Sigma HSM = Nikon AF-S = Canon USM = fast, silent focusing with the focusing motor built into the lens.

The D90 does have a focusing motor built into it. That's for Nikon's first-generation autofocus system where the body motor drives the lens via a mechanical coupling. (You can see the coupling at 7 o'clock on the camera's lens mount.) It does work and you can use the non-HSM lens, but compared with the HSM version the autofocus will be slow and noisy.
 
Thanks for information ..sometimes it get a little confusing to say the least ...
 
Unfortunately Nikon's system can be confusing. They've made some questionable engineering/design decisions over the years, which have resulted in issues of incompatibility and confusion.

The most obvious of these decisions was the autofocus system. I really don't know why they decided to put the focusing motors in the camera bodies rather than the lenses(*) but it was clearly the wrong decision. Canon's solution with the focusing motors in the lenses was faster and quieter (ie better) and so Nikon had to copy it or risk being left behind.

(*) Maybe economics. Maybe it was perceived at the time to be a more cost effective solution, in the same way that Sony et al claim that in-body image stabilisation is more cost effective. Trouble is, the pro market tends to prioritise "effective" over "cost effective".
 
StewartR said:
The most obvious of these decisions was the autofocus system. I really don't know why they decided to put the focusing motors in the camera bodies rather than the lenses(*) but it was clearly the wrong decision. Canon's solution with the focusing motors in the lenses was faster and quieter (ie better) and so Nikon had to copy it or risk being left behind.
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When Canon moved to AF motors in lenses they made the very brave, and correct decision to change the lens mount as well. Nikon's decision to still use the old lens mount has led to the sometimes odd hangovers, however it has been the thick end of 20 years since Nikon released a lens that uses in body AF, so its not that confusing ;)
 
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