Just thought I'd post about my experience with the Katz eye split prism screen for the T2i (550d).
First of all, I'd just like to say that the ordering experience went very smoothly. Focus screen was shipped 2 days after I placed the order and the questions I had were answered very promptly by Rachael Katz. Shipped was expensive, but it arrived very quickly which was nice.
Installation went without a hitch. Very very easy to do. I didn't take any picture because I thought the pdf + pictures on the website did a fantastic job of explaining how to change the focus screen. All in all it took me about 5 minutes to change out the focus screen.
I opted for the basic focus screen for the T2i. I did not go with the optibrite treatment because I am using this mainly for my Sigma 30mm F1.4 and my Tamron 60mm F2.0. If you don't go with the optibrite treatment your screen will show more contrast and therefore theoretically it will be easier to manual focus. I also did not get the engraved focus points either, but I use center focus all the time so it would have been a waste of money for me. For those that don't know what optibrite is, it just allows you to have a brighter viewfinder when using slower lenses.
At first, I hated not having the center focus box. The more I used the split prism though, the better I liked it. Now rather than having a little box light up with focus confirmation, I would get the split prism snapping into a continuous image and the microprism donut around the split prism, become a clear bright image so I knew I had perferct focus!
While I didn't buy the focus screen for better confirmation during autofocus, it sure helps! (wanted to buy it first before I purchased some MF only lens')
Autofocus on the t2i vs manual focus:
Autofocus is much faster obviously. The tests I have done, you can autofocus in a fraction of a second where manual focus takes about 2-3 seconds to nail focus and in low light up to 5 seconds. I did say nail focus though. Manual focus for me was very accurate whereas the autofocus was just accurate. The cramped viewfinder of the t2i and rebels hadn't really bothered me up until this point, but it sure would be nice to have a better viewfinder. That is another issue though I'm afraid. While on this subject though, I have very good vision and I have to think in order to get the most out of the cramped viewfinder and the split prism you will need good vision as well, especially on wider angle lens'. The more I use the split prism the better I am getting as well so the time it takes me to focus will more than likely drop a bit, but still be nowhere near as fast as autofocus.
Thought I'd make some bullet points on some pros and cons:
Pros:
+ Great auto focus confirmation via both the split prism and microprism collar
+ Manual focus equates to focusing via 5x in live view. 10x live view is more precise.
+ Manual focus via the viewfinder is much much quicker than using liveview.
Cons:
- Lose focus point confirmation
- Can't tell what focus point your on while looking through the viewfinder
- Dark viewfinder when used with slower lenses without optibrite treatment
- Metering and more specifically spot metering may be affected at lower f stops. (I haven't noticed any change in metering)
- Low light focusing is much hard than anticipated where contrast is lacking!
As you can see, there is as many cons as there is pros. I'm no pro though and I am really loving what this split prism gives me. I am ready to add some manual focus lenses!
