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G'day all,

I just picked up my 80-200mm f2.8 lenss today. Unfortunately there was no instruction book with it.

I've managed to figure out how the lense works but am still unsure about the little switch towards the front of the lense with a limit and full option.

Could someone please tell me what this is for?

Sounds like a focus-limiter to me, can be handy if the AF hunts due to two objects at different distances being close in the frame.

MCWB wrote:Sounds like a focus-limiter to me, can be handy if the AF hunts due to two objects at different distances being close in the frame.

So what does it do and how/when do I apply it?

Baboo I'll give this a try.
The focus limiter switch, as the name would suggest limits the focus range of the autofocus. So that effectively by flicking the switch on eg when focussing on near objects the limiting switch will tell the auto focus not to bother hunting in the far range and vice versa.

The limiting switch, once activated, will tell the autofocus computer to remain in that focus range you are working at (near or far). It really does speed up focusing because it concentrates on the band of focus you have limited it to.

You will find, however, that with the limiter switch on if you begin to ask it to focus outside that focus band it will hunt and not be able to focus until you switch it off.

I use it regularly to speed the autofocus up. For example last trip i was trying to track some galahs arriving and leaving a perch in a tree fairly high up. So I focussed on the perch normally then hit the focus limiter. It then made the autofocus stay focussed(so to speak) on that focus range even if my tracking of the birds was sidetracked it quickly regained focus because it knew not to bother focusing on e.g the branch 3 metres in front of you that just blew across your screen.
Sorry Baboo I hope this has helped. I almost confused myself. Either way experiment and you will know what i'm talking about. It's aneat trick.
cheers
marco

Thanks Marco,

I kinda understand what you're trying to say. If required, focus on the subject and then it'll limit the focusing within a specified range on either side of that original focus.

Yeah??

Baboo Good! Smack on mate. Give it a go.
Marco