Sigma 17-70mm what is "IF"?

i just ordered this lens from amazon and realized there are two versions of it.

one is "IF"
http://www.amazon.com …ance#moreAboutT​hisProduct

and this one isnt, but its a few dollars more.
http://www.amazon.com …314001&pf_rd_i=​B000EGAMBW

whats the difference?

As far as I can tell it's a Typo. I think it should be AF as in Auto Focus.

"IF", as it relates to lenses, usually means "internal focus(ing)"

In this case, it is probably a typo, even though, according to the product info, it does offer "inner focusing".

i just wanted to make sure i ordered the right lens...lol had me worried.

runninmann wrote in post #3480479
"IF", as it relates to lenses, usually means "internal focus(ing)"

Which means, that the lens does not externally telescope to zoom, but handles it internally. Better for cleanliness

Deckham wrote in post #3480512
Which means, that the lens does not externally telescope to zoom, but handles it internally. Better for cleanliness

No, that internal zooming. Internal focus means the front element doesn't rotate and length doesn't change during focusing.

i would tell you to buy it from sigma4less, but apparently their site isnt working right now . they ahve it for 319.

e r y k wrote in post #3480523
i would tell you to buy it from sigma4less, but apparently their site isnt working right now . they ahve it for 319.

i looked at sigma 4 less but i wanted to expedite shipping and when you added in the shipping cost it was cheapest for me from amazon (47th street photo).

runninmann wrote in post #3480518
No, that internal zooming. Internal focus means the front element doesn't rotate and length doesn't change during focusing.

Then I stand corrected.
Naked, shivering, and corrected.

Deckham wrote in post #3480638
Then I stand corrected.
Naked, shivering, and corrected.

That's kind of scary!

47th St. Photo, are these guys reliable or are they one of the "infamous" NY dealers?

00silvergt wrote in post #3481903
47th St. Photo, are these guys reliable or are they one of the "infamous" NY dealers?

i bought through amazon, and checked the reseller ratings through amazon... there were a few complaints but not enough to worry me compared to the positive ones.

http://www.amazon.com …er=&seller=A1P9​QRDRYY6FXL

According to Sigma, the 17-70 does feature "IF," so it's probably not a typo. However venders often don't include some things in the name and when it comes to a big vender hub like Amazon, things can get confusing.

http://www.sigmaphoto.​com …s.asp?id=3315&n​avigator=6

just thought it was strange and kinda worried me, i didnt see the other lens (with the full title) until i already ordered the first one. and the one i ordered is cheaper, from the same vendor... probably a damn grey market...lol

Mrvile wrote in post #3482999
According to Sigma, the 17-70 does feature "IF," so it's probably not a typo. However venders often don't include some things in the name and when it comes to a big vender hub like Amazon, things can get confusing.

http://www.sigmaphoto.​com …s.asp?id=3315&n​avigator=6