Recently, I upgraded from the 5D Mark II to the Mark III. I absolutely love the Mark III, but I was having trouble getting accurate focus with my manual lenses through the viewfinder. With the 5D Mark II, Canon made different focusing screens that you could purchase and swap out. There were other third-party focusing screens you could purchase as well, including split focusing screens, and precision matte focusing screen. I was a little disappointed to find out that the Canon did not provide this capability to the Mark III (sort of). Canon has listed the 5D Mark III's focusing screen as a not user-replaceable. Maybe it's a push to drive sales of more Auto Focus lenses? In any case, what I was able to do is fit the 5D Mark II's Eg-S Precision Matte focusing screen, into the 5D Mark III. Because the Eg-s Focusing screen is meant to fit into the Mark II, it is missing some of the side grooves that are present in a Mark III focusing screen. However, they are nearly identical in size, and I was able to install it without any modification to the screen. It has been holding for several weeks now, and seems to fit securely.
I made a short video below showing the process of changing the focusing screen in the Mark III with an Eg-s Focusing screen.
I made a short video below showing the process of changing the focusing screen in the Mark III with an Eg-s Focusing screen.
This method saves you a lot of money from buying specialized, third-party focusing screens. At the time of this posting, the Eg-s Focusing screen for the 5D Mark II is only $35 (link below).
http://www.amazon.com/Canon-Eg-S-Precision-Focusing-5D-Mark/dp/B001KBZ3S2
You can purchase specialized, third-party focusing screens that are made-to-order, from only a few online retailers. But prices for those screens are $90 +
http://www.focusingscreen.com/index.php?cPath=21_134
Hope this helps! Let me know if you have any questions!
http://www.amazon.com/Canon-Eg-S-Precision-Focusing-5D-Mark/dp/B001KBZ3S2
You can purchase specialized, third-party focusing screens that are made-to-order, from only a few online retailers. But prices for those screens are $90 +
http://www.focusingscreen.com/index.php?cPath=21_134
Hope this helps! Let me know if you have any questions!