Tamron SP AF90mm f/2.8 1:1 Macro Lens question.... "What does this do"

I have recently purchased a second hand Tamron SP AF90mm f/2.8 1:1 Macro lens for my EOS20D - I'm really happy with it.

I have one question though (since it didn't come with the manual) - what is the switch for "FULL / LIMIT" used for?

Thanks

Depth of Field scale, I think.

Here is the manual:

http://www.tamron.com/​assets/pdfs/272E.pdf

I was wrong - it is a 'focus limiter'

See page 7 in that manual.

Right - focus limiter - so that when you're using it as a "normal" lens, not in macro, it won't try to rack out all the way to 1:1 while seeking a good focus. Thanks for the link kiwibloke - mine was also a used/no manual purchase.

Google found it for me - in about 0.2 seconds - according to them.

Thanks.... and Merry Christmas

Easy solved, everyone beat me to it lol. Enjoy the lens it is a great unit.

when you turn the switch to "LIMIT" it will limit the focus to about 4:1. So you can use this when shooting long distance pics e.g. portrait with the lense. Focus will be quicker & as lense will have to travel less to focus i.e from infinity to 4:1. When shooting macro switch to full. Or another way is to manually turn focus ring all the way to 1:1 and then turn switch to "LIMIT" and now autofocus will focus from 1:1 to 4:1 only thus making macro focus easy.