I know the Canon 70D doesn't have a user-replaceable focusing screen, and only Katz-Eye sell a microprism focusing screen (or ANY focusing screen) for this camera. It seems that you can replace the focusing screen but need to remove two screws first.
What I'd like to know is whether the Canon Matte Ef-S focusing screen that's designed for the 40-60D will work with the 70D, because it's way cheaper than the Katz-Eye one (which is $105, compared to about $30 for the Canon one). The Canon one also says it's for 1.8-2.8 lenses - what if I use 1.4?
I'm really struggling to nail focus with the Sigma 50 1.4 and its AF is unreliable, even after spending $100 on calibrating it to my 70D. I would also like to get a new manual lens (an old one, like Takumar or Helios), I really like their color rendition and only having a 50mm lens is very limiting.