Focusing screens

[chameleon]

Is it worth using focusing screens? I've seen the Canon Ef-D and Eg-D screens, I assume they are just a framing overlay for getting horizontal n verticals right? Personally I'm very bad for slightly off kilter photos. I quite like the idea of the Ef-S which aids focussing with a wide 1.8 or 2.8 lens. Are they easy to fit?

 

[thompo]

I have the EF-s in my 40d.

Deffo makes manual focusing a bit easier. Though it seems a lot darker using non 2.8 lenses.

Took about 5mins to fit

 

[pearce_jj]

I read somewhere the standard screen is only good for manual focusing at >f2.8, dunno if that's right though.