So I know that I want a image that can give me at least 16mm (12mm on APS-C sensors).

My problem is I don't know whether to get a lens that is a DC/EF-S or DG/EF (Sigma and Canon terms) as I want to one day upgrade to a Full Frame camera.

If I know I want to upgrade should I get full frame lenses and save myself the pain and moeny of having to buy a new set of lenses down the road?

I know what I want on focal length but I'm not sure if it's wise to buy for the future rather than the now...

HELP PLEASE...

Hi Vera
Live for now - go for the best you can get for your present camera imho. 
R

The Sigma 10-20 apparently works down to 12mm on a full frame (may have to check in terms of quality - i'm thinking lots of CA and distortion with a bit of vignetting...).  I have it for my 30D (1.6x crop) and it is a good lens - check my uploads from Westonbirt - they are all taken with it (so far).

But yeah - the here and now - good lenses dont tend to loose too much value second hand imo...

Hmm Tricky I would go for the Sigma 10-20  unless you  are sure you will upgrade to the full frame then buy the 17-40mm Canon.. Unles your trial was not  too good?  

i thought of that few days ago which is why i bought me the sigma 10-20 for £290 few days ago. This way i haven't lost much if i change my camera in future and i also can't wait to go try it out on some landscape photography now that i have just taken a weeks holiday from work.

hello PeeWee !

i understand your dilemn ! I've got the same one year ago ! So i bought a lens for my canon 20d, just for him. And about fullframe -> i've returned to classical film, because the price of full frame digital body is really big (for me lol)

... i agree with onslow and inshaala : live for now and there ! ;o)

see ya :o)

Thanx for the input guys.

I went to the British museum and tried my kit lens at 18mm on the reading room and was really disappointed at the view. The was a review in Digital Photo with the ultra wide angles and their pics give me a good idea of what to look against...

I asked Sigma to create a 10mm f:2.8, argueing that it would be cheaper to create than a zoom. They didn't respond yet, but when they do and I get, as "godfather" of the lens, my free copy, I'll send you my 10-20 zoom.

(Trying to be serious for a moment)

the 10-20 is a fine lens.  Yet I always use it at 10. as my main lens starts at 17 or so.

10, or 16 on the 350-400-40 etc , deforms a lot. All trees look like they are singing in close harmony when you tilt a bit upwards.

also, because of the enormous angle, a pola, being angle-dependant, is not always useable. It also has to be so thin that it's difficult to screw it off the lens.

you can also get bizarre light effects in a dark room with a light source in view. but that may well not be typical for this lens.

ahh...forgot: autofocus doesn't always work as everything becomes very small, excepting the forground object of course. This is no drama as you get a huge dof, but still...

Thanx for the info!
And I will gladly accept your 10 - 20mm when Sigma answers you! :)