Hi guys!
Since ive never owned a FF or manual focus lens i thought id check with you.
Im also one of those who are getting the 5Dmk2 and the first lens im getting with it is the 35L, and when it comes to wideangle lens im starting to wounder if theres any alternative lenses that i chould check out.

Since you have to use manual focus, are you guys using splitscreens? How does that affect when you use regual EF AF lenses?

Is there any fast lenses around 20mm that you recomend or should i just go for the 17-40L.

Fast? No, not many fast primes around 20 that will save you money. Always the Oly 18/21 f/3.5 which are small and great performers. Of course, the 18 is around $800+ and the 21 $450+. Oly 24mm f/2.8 is in the $150-$200 range.

I use the Ee-S focusing screen with lenses, some fast (f/1.2-f/1.4), some slower (f/2.8... slow).

Fast around 20mm starts to be more like 2.8.
See the current CZ 21 and Nikon 14-24 discussion. Most of the people in this forum are shooting the 14-24 Nikon on Canon.

As far as focus screen, I perfer split prism because it's brighter on slow lenses than the Ee-S.

Leica has a new introduced an M-mount (rangefinder only) 21mm F1.4 and 24mm F1.4 - both knock outs (in terms of MTF s and cost) , but.....

As others have said, when you get under or around 18-25mm you typically start at 2.8 - one that springs to mind that would require modification to either the lens or your 5D2's mirror is the stellar Leica 19/2.8 ver2, but there are a number of lenses in that range from Nikon - including the Ai/AiS primes, the spectacular 14-24G with special Hubsand adapter, the Contax CZ 21/2.8 (and it's pending ZE replacement), etc.

Don't think you'll find many fans of the 17-40 in this neck of the woods. ;>

I really like my 24L... plenty of CA but it is generally uniform across the frame and thus correctable.

My Tokina 17/3.5 ATX-Pro has unpredictable yellow/blue CA that worsens in the corners making it practically uncorrectable.

I'm holding out for the ZE 21mm as I'm a prime kinda guy, but the Nikon 14-24 is a good option especially if you want a big range in one big lens.