Does Sigma HSM work the Same Way as USM

The reason I ask is that I found my new Sigma HSM lens would not allow
manual focus unless the AF switch is off. I thought one of the
advantages of USM or HSM is that you can always manually focus the
lens regardless of AF function. This is certainly the case on all my
USM lenses, even the cheap ones.

"panabiker" <ghuang@comcast.net> wrote in message
news:55681195-2801-4db6-a948-db029eaed665@p25g2000hsf.googlegroups.com...
> The reason I ask is that I found my new Sigma HSM lens would not allow
> manual focus unless the AF switch is off. I thought one of the
> advantages of USM or HSM is that you can always manually focus the
> lens regardless of AF function. This is certainly the case on all my
> USM lenses, even the cheap ones.

Hello.

Sounds like a Sigma design thing. I had a Sigma macro where manual focus
needed to move a switch and a focusing ring whereas on the Canon macro it
was just one switch.

Regards, Ian.

panabiker wrote:
> The reason I ask is that I found my new Sigma HSM lens would not allow
> manual focus unless the AF switch is off. I thought one of the
> advantages of USM or HSM is that you can always manually focus the
> lens regardless of AF function. This is certainly the case on all my
> USM lenses, even the cheap ones.

My Sigma 12-24 doesn't have a manual focus switch.

--
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Paul Furman wrote:
> panabiker wrote:
>> The reason I ask is that I found my new Sigma HSM lens would not
>> allow manual focus unless the AF switch is off. I thought one of the
>> advantages of USM or HSM is that you can always manually focus the
>> lens regardless of AF function. This is certainly the case on all my
>> USM lenses, even the cheap ones.
>
> My Sigma 12-24 doesn't have a manual focus switch.

FWIW, my Tokina 12-24 does, but it's flipped by sliding the focus ring
forwards or backwards. Can be missed pretty easily.

--
Jeff R.

On Thu, 17 Jul 2008 11:46:15 +1000, in rec.photo.digital "Jeff R."
<contact.me@this.ng> wrote:

>Paul Furman wrote:
>> panabiker wrote:
>>> The reason I ask is that I found my new Sigma HSM lens would not
>>> allow manual focus unless the AF switch is off. I thought one of the
>>> advantages of USM or HSM is that you can always manually focus the
>>> lens regardless of AF function. This is certainly the case on all my
>>> USM lenses, even the cheap ones.
>>
>> My Sigma 12-24 doesn't have a manual focus switch.
>
>FWIW, my Tokina 12-24 does, but it's flipped by sliding the focus ring
>forwards or backwards. Can be missed pretty easily.

But the Tokina doesn't have it's own focus motor (USM/HSM/etc), it
uses the cameras screw drive.

me@mine.net wrote:
> On Thu, 17 Jul 2008 11:46:15 +1000, in rec.photo.digital "Jeff R."
> <contact.me@this.ng> wrote:
>
>> Paul Furman wrote:
>>> panabiker wrote:
>>>> The reason I ask is that I found my new Sigma HSM lens would not
>>>> allow manual focus unless the AF switch is off. I thought one of
>>>> the advantages of USM or HSM is that you can always manually focus
>>>> the lens regardless of AF function. This is certainly the case on
>>>> all my USM lenses, even the cheap ones.
>>>
>>> My Sigma 12-24 doesn't have a manual focus switch.
>>
>> FWIW, my Tokina 12-24 does, but it's flipped by sliding the focus
>> ring forwards or backwards. Can be missed pretty easily.
>
> But the Tokina doesn't have it's own focus motor (USM/HSM/etc), it
> uses the cameras screw drive.

Oh.
Forgive my ignorance.
'fraid I don't dwell on these mechanics.

Carry on...

--
Jeff R.

<me@mine.net> wrote in message
news:4fgu745c56n3ql4i9ff8soae72mkpc3g2b@4ax.com...
> On Thu, 17 Jul 2008 11:46:15 +1000, in rec.photo.digital "Jeff R."
> <contact.me@this.ng> wrote:
>
>>Paul Furman wrote:
>>> panabiker wrote:
>>>> The reason I ask is that I found my new Sigma HSM lens would not
>>>> allow manual focus unless the AF switch is off. I thought one of the
>>>> advantages of USM or HSM is that you can always manually focus the
>>>> lens regardless of AF function. This is certainly the case on all my
>>>> USM lenses, even the cheap ones.
>>>
>>> My Sigma 12-24 doesn't have a manual focus switch.
>>
>>FWIW, my Tokina 12-24 does, but it's flipped by sliding the focus ring
>>forwards or backwards. Can be missed pretty easily.
>
> But the Tokina doesn't have it's own focus motor (USM/HSM/etc), it
> uses the cameras screw drive.

The Tokina lenses for use with Cano bodies must have their own motors as
there is no screw drive from Canon bodies to the lenses.

Regards, Ian.