Sigma 10-20mm focus ring

[Janice]

My Sigma 10-20mm has suddenly started acting a bit funny.

When I turn the focus ring it doesnt stop turning at infinity...it just carries on turning forever!!! it doesnt focus forever, just the normal range..The numbers stop at infinity but the ring doesnt.

If I take it back does it have to go to where I got it as that is Bristol and I live in Essex! Can it just be another Sigma dealer??

 

[siejones]

It's supposed to do this.

I think it's called full-time manual focusing. You can litterally hold the focus ring even when the motor in engaged.

Both my Canon 17-40 and 70-200 both do this.

 

[petemc]

Yup its meant to. Mine does too.

 

[Grendel]

......and mine

 

[Jonnyreb]

Dont worry Janice - this is something you can't break! As Sie days its an internal clutch mechanism (I cant remember what ohter lenses you use, but it's standard in most EF lenses.....)

 

[Janice]

thats funny ive had it a month or two then yesterday it seemed to make a strange noise when focusing now ive only just noticed it does this!!

So how the hell do you know when you are at the end of the focusing distance etc. keep looking at the lens to see where the infinity mark is??

Well i accept it is supposed to.....but i still cant see why! :shrug:

Id prefer to know thats my lot when I get to the end! (if you'll pardon the expression!!)

 

[Ian T]

You can break it. A mate of mine has done two of them (Canon-fit) now. They're stuck on infinity. Not sure how he managed it, unless it's the M/AF switch that's broken...

 

[Jonnyreb]

thats funny ive had it a month or two then yesterday it seemed to make a strange noise when focusing now ive only just noticed it does this!!

So how the hell do you know when you are at the end of the focusing distance etc. keep looking at the lens to see where the infinity mark is??

Well i accept it is supposed to.....but i still cant see why! :shrug:

Id prefer to know thats my lot when I get to the end! (if you'll pardon the expression!!)

There should be a marked difference in the damping when you get to closest and infinity....... Failing that, just stop focussing when the bloody object seems more sharp than soft

 

[TomB]

With mine I find it pretty easy to 'feel' when it reaches the end of the focussing distance - theres a slight but distinct sort of 'thunk' as the clutch disengages (or is it engages? dunno - not very mechanically minded!).

 

[siejones]

thats funny ive had it a month or two then yesterday it seemed to make a strange noise when focusing now ive only just noticed it does this!!

So how the hell do you know when you are at the end of the focusing distance etc. keep looking at the lens to see where the infinity mark is??

Well i accept it is supposed to.....but i still cant see why! :shrug:

Id prefer to know thats my lot when I get to the end! (if you'll pardon the expression!!)

You can kinda of feel with it hits the end...a gentle stop before it goes past.

I think it's something to do with being able to quickly manual focus overriding the auto without having to click the switch over. For instance the drive is going to auto but you hold the focus ring against it. On other lenses this would snatch at you hand and strain the motor.

I don't think I have explained that right