Author Topic: Focus limiter  (Read 2690 times)

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Offline gazraa

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Focus limiter
« on: December 10, 2008, 10:20:28 PM »
Can someone please explain to me in simple terms how you use the focus limit buttons on the 300mm f2.8 or Sony 70-300mm SSM?

I'm a little unsure how they should be used.
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Offline tpe

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Re: Focus limiter
« Reply #1 on: December 10, 2008, 10:33:07 PM »
At a guess if it is not the same as the 70-200 then (ie forward normal and back limitied to over 3m) then it is a focus and lock, free limiter like the canon ie focus on subject then turn on and you can then limit the range focused to to however many degrees of rotation around the point where you turned it on, a bit like an electronic version of the HSG version? Only wild guess though.

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Offline AScot

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Re: Focus limiter
« Reply #2 on: December 10, 2008, 10:38:04 PM »
On the 70-300G SSM the focus hold button does just that, when pressed it holds the focus allowing you to reposition your shot.

The focus mode/range switch when set to infinity-3m limits the focusing of the lens to that range, thereby increasing the speed of the lens when using the long end. The short end, below 3m is where it is slower.
Cameras, Sony A700, A850, A77, Lenses, Sony 70-300G, 16-80CZ, 28-75 f2.8 SAM, Minolta 500 f8 Reflex, 300 f4 G, 200 f2.8 G, 100 f2.8 (D) Macro, 50 f1.7, 28 f2.0, 28-135 f4, 70-210 f4,  Sigma 21-35 f3.5-4.2. Minolta TCs x1.4 & x2.

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Re: Focus limiter
« Reply #3 on: December 10, 2008, 10:38:53 PM »
Occasionally the AF will hunt and this takes time with some long lenses or macros that have a fine step in their focus control.  You use the limiter to keep the focus range limited to near the range you are working to avoid long travels to infinity (focus!) and back.

For example if you're using a long FL to focus on a nearby object, if the AF doesn't get a phase lock, it will continue running the focus to infinity and then all the way back until it sees lock.  Can be long and frustrating.  Use the locks to constrain the range.

I usually manual focus so it is not much of an issue.  I have the range limiter on a couple lenses.

Offline AScot

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Re: Focus limiter
« Reply #4 on: December 10, 2008, 10:55:33 PM »
The range limiter on the 70-300mm G SSM has 3 positions, (Full AF), (Infinity-3M) and (MF). The first and last are self explanatory, the middle one is as I said above and limits the focus travel from Infinity down to 9 Metres. Some other lenses I have with focus limiters have a low and a high setting, which works differently. The 70-300 has an SSM motor and it doesn't go to infinity and back to get a reference point like non SSM lenses. I think. :D
Cameras, Sony A700, A850, A77, Lenses, Sony 70-300G, 16-80CZ, 28-75 f2.8 SAM, Minolta 500 f8 Reflex, 300 f4 G, 200 f2.8 G, 100 f2.8 (D) Macro, 50 f1.7, 28 f2.0, 28-135 f4, 70-210 f4,  Sigma 21-35 f3.5-4.2. Minolta TCs x1.4 & x2.

Offline Fud

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Re: Focus limiter
« Reply #5 on: December 11, 2008, 12:44:31 PM »
Gazraa I think the focus limiter on the 300 F2.8 works the same as the one on my 600 F4.  What you do is undo the little screw, make sure the arrow on the small threaded ring lines up with the mark on the lens barrell and focus on an object at the distance you want to limit the focus to.  Now if you turn the small threaded ring on the lens anti-clockwise, as you look from the camera, as far as it will go and then tighten the screw the camera will now focus between the distance you set and the nearest that the camera will focus (I think that's the right way).  If you turn the threaded ring clockwise as far as it will go the lens will focus between the distance you set and infinity.
A900+VG, A77+VG, Minolta 17-35G,  Sony CZ24-70 F2.8,Sony 70-200 F2.8 SSM, Sony 70-400 SSM, Sony 135STF,85 F1.4, 200 F4 Macro, 600 F4 HS APO

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Re: Focus limiter
« Reply #5 on: December 11, 2008, 12:44:31 PM »