Alternative focusing screen for Canon EOS
I'm new on this SLR autofocus camera, and noted that the viewfinder doesn't help a lot when doing manual focus. I searched the 'net and found this "alternative focusing screen" for SLR/DSLR cameras, but nothing specific to my 3000V.
Is there any drawback on using alternative focusing screens in a Canon EOS SLR/DSLR, to help manual focusing?
Apparently, they make the viewfinder image more dark (microprism focusing screen), but other than that, is there any side effects? Does it affect the autofocus (I think no, but not sure)?
Is there an alternative focusing screen for the Canon EOS 3000V (film camera)?
Links I found about these subject that seems provide some information:
Focusing Screen in Wikipedia
Focusing screens available for Canon EOS 50/55 (film camera)
I'm trying my best here.