Canon 70-200 2.8II IS - does the switch 1.2m - infinity matter?

The manual states that this switch might impact focusing speed? Does anybody use this switch actively and sees an impact?

It should only help make it focus faster by limiting the distance it needs to focus to your desired subject (assuming its more than 2.5m away). Obviously it takes longer to focus from MFD to infinity than from 2.5m to infinity... even though it’s fairly quick either way. It’s not something I use often, but I’ve used it occasionally when I’ve been shooting sports from the sidelines and have umpires, coaches, etc walk in front of me often or if I want to make sure that my focus stays on the other side of a fence that I’m shooting through. I can’t say if it has helped tremendously, but it doesn’t seem to slow anything down.

I haven’t yet found a use for the 2.5m-6.4m setting on my 300 2.8 IS. So if someone uses that, I’d love to hear what it’s being used for.

Lyndön wrote in post #18649316
It should only help make it focus faster by limiting the distance it needs to focus to your desired subject (assuming its more than 2.5m away). Obviously it takes longer to focus from MFD to infinity than from 2.5m to infinity... even though it’s fairly quick either way. It’s not something I use often, but I’ve used it occasionally when I’ve been shooting sports from the sidelines and have umpires, coaches, etc walk in front of me often or if I want to make sure that my focus stays on the other side of a fence that I’m shooting through. I can’t say if it has helped tremendously, but it doesn’t seem to slow anything down.

I haven’t yet found a use for the 2.5m-6.4m setting on my 300 2.8 IS. So if someone uses that, I’d love to hear what it’s being used for.

Lots of uses for that.
Birding with a feeder. Common that distance would be 3-4 metres. Perfect for that.
Today I was using 3m-10m range for small birds, using 1000mm. It's a real challenge to get an AF point on them let alone actually achieve focus.
Limiting focus range is a big help.

Ah, that makes sense. I knew there was a good reason for it, but I’m not a birder so it wasn’t immediately apparent.

Works for motor racing and aircraft in flight too.
It's rare that you'll ever be within 1.2m of a jet and it saves the AF racking all the way if you lose focus.

you don't have to be a birder to shoot close up. you could be a flowerer or a dogger .

ed rader wrote in post #18652321
you don't have to be a birder to shoot close up. you could be a flowerer or a dogger .

You do know what a “dogger” is this side of the pond?

i'm scared to ask in polite company so i'll do a google search

ed rader wrote in post #18652946
i'm scared to ask in polite company so i'll do a google search

Hint. The smiley you used at the end of your previous two posts isn’t entirely inappropriate...

Make sure your anti virus is up to date before you search. That's definitely the 'wrong end of the net'

Choderboy wrote in post #18653470
Make sure your anti virus is up to date before you search. That's definitely the 'wrong end of the net'

Dang - you just made me search for this word....

Choderboy wrote in post #18653470
Make sure your anti virus is up to date before you search. That's definitely the 'wrong end of the net'

Actually, the activity referred to has its own Wikipedia entry. Amazing how we repressed Brits have come on isn’t it?

The difficulty is avoiding double-entendres, which I have singularly failed to do in this post...

Just to save all the other non-English speaking people the trouble of seedy guessing:
Dogger (noun)
1. a broad-bowed two-masted fishing boat used especially by the Dutch in the North Sea
2. geology a formation of mid-Jurassic rocks in N England

(still doesn't answer my original question...)

To answer you original question. I think post #2 already did, but here’s my two-penn’orth.

In the case of my original f/4 version at least, the focus limiter makes AF noticeably faster and more accurate under normal (mid to long distance) conditions as it prevents excess focus movement. Occasionally, on full range the lens will fail to find focus.

Exactly the same applies to my Nikon 80-200mm f/2.8.

JohnB57 wrote in post #18653975
Actually, the activity referred to has its own Wikipedia entry. Amazing how we repressed Brits have come on isn’t it?

The difficulty is avoiding double-entendres, which I have singularly failed to do in this post...

It does seem to be unique to the Brits. Or at least they are the ones who share the fact that they participate.
There are at least a few ways the focus limiting function could be worked into an 'on topic' discussion.

For example, say you're enjoying your usual Friday night dogging at the local spot. Upon entry, the appointed dogging master of proceedings inspects any lenses to ensure the focus limit is set to 1.2m and the switch covered so that only fellow doggees you are actively participating dogging with could be photographed, not unknowing doggers further away who may not be aware and willing to give consent for the obviously NSFW photos to be taken, with obviously embarrassing consequences.

There, no double-entendres and I'm sure an entirely original description for the use of a focus limiting switch.