[Rainer]

I am not sure for which format I should get the lens

 

Well, eventually one important question is this:

What are the situation where you will use this lens? ... Which of

your cameras will you usually have with you in these situations.

Eventually it turns out, you will need the UWA only when you have

one certain camera with you ... in that case, you have an anwser.

 

If I compare images that I did with the EFs 10-22 on a 300D to

those I have from an EF 17-40 on a 5D, I usually prefer the latter,

but I couldn't really blame the lens for it.