Did I dream about it or not?

I remember hearing a term which I forgot.

When you have a zoom lens, you can zoom in/out and the focus will stay the same.

How is it called?
What lenses have it?

The thing is: I thought my 70-200 sigma had this characteristic, but it doesn't. I looked at all of the canon's 70-200s and BH says nothing about that.

Did I dream this up?

No you weren't dreaming,such lenses exist.

I vaguely recall it's called parfocal or something similar,and seen lists of lenses that do it.They used to be more common with manual focus lens designs but the advent of AF made it much less usefull a feature to have.

Just one side note while i have the floor so to speak - when using such a lens one must focus at the tele end and all focal lengths will be in focus.
If one focuses at the wide end then zooms to the tele end it's very likely that the focus won't be accurate.

Wow,i actually remembered the right word!

Here is a list of canon zooms that are parfocal.Note that this list may not be totally up to date with the latest lenses


http://www.rogercavana​gh.com/helpinfo/30_par​focal.stm

Parfocal...

what's funny is that my sigma is lens is not actually parfocal. I do have to refocus after zooming in/out.

Is this an assembly defect or is it happening to all of them?

I did some searching on the web and couldn't find a thing about that particular sigma being parfocal.
There was plenty of info about the canon 70-200's being so ,but it's looking alot like the sigma isn't.
An email to sigma would clear it up for sure