But you won't get 10mm out of it, you have to account for your crop factor, 1.5 or 1.6 so it's going to be 15 or 16mm.

Alan.

Yes I realise this.

I want 10mm so I can have a cropped equiv to what we used to call wide - 16mm.

That's why I wasn't going to get one as I was going full frame with a EF 17-40

Now I'm staying with my cropped 40d for a while, I want the wide 10mm or 12mm so I get 16mm or 18mm.

10mm on the 40D works out to be a 16mm anyway which is as low as you can get on a full frame anyway...

It all depends on what you want to do or where your future lies if you get a full frame... I tried the 10mm out on my 400D to see if i would use a wide angle lens and now want to invest in the 17-40mm for my FF camera

I use the 17-40, its looooovely

Cant comment on the lenses you have quoted, but my bro in law uses this one:

http://www.canon.co.uk/For_Home/Prod..._USM/index.asp

Not sure on your budget, but he has taken some stunning landsacepes and panoramas with it.

A bit over my budget I'm afraid Dawn. Perhaps that's one for my full frame future plus It wouldn't be 16mm wide on a cropped sensor anyway - about 24mm.

The two that I'm looking at are

Sigma 10-20mm f/4-5.6 EX DC HSM

Sigma 12-24mm f/4.5-5.6 EX DG ASHPHERICAL HSM

I've a head to head review in one of the recent fot mags with 10-20 Vs 12-24. I'll dig it out and scan it for you. nothing like independent advice eh? LOL

Actually don't have time to find the results right now but generally the 12-24 'wins' on overall quality. Google some online searches which is what I did. In the end though it's so close I think it's just a case of which suits you more as both are well proven and capable by thousands and thousands of buyers. I did say earlier the Tokina 12-24 is acknowledged as 'better' if you were looking at that focal length but I doubt most of us can tell much difference certainly at DX format.

Having not bought any kit for a while I was slightly shocked at the high street prices on Saturday. I knew prices would be a bit dearer than they were a few months ago but I was surprised by how much more things were.

Anyway - having made up my mind, I thanked the shopkeeper for his help, came home and bought the 10-20 online

It is a very enjoyable lens. You will see I have posted a few pictures taken with my 10-20 over the last week or so.

It's a shame regarding the High Street retailers, they just can't compete with box shifting warehouses. Although as an ideal principle most of us want the personal service, and support the shop in the street, often it means paying 25% or even 50% more. Having said that, you often now end up with shop assistants that know little about the product. They just sell you the item you want and you walk out the door.