Executive Summary
Buy the Canon Ec-A, it is super good.
The Long Version
I've tried the K3 based screen from focusingscreen.com, which is of similar layout and type to the offerings from KatzEye, and the Ec-A is absolute night-and-day better than that screen.
I there is a certain romance about manual focus lenses. The well-damped focus rings, the now (mostly) absent depth-of-field scales, the built-like-a-tank-ness of the old Taks and the new Zeiss and Voigtlanders. It's a wonderful experience.
That is until you try to focus them.
Now I knew what I was getting into when I went mostly manual, and I was proactive and got myself a screen. Did some reading and found that the K3 seemed like a popular option. It had the split prism and microprism collar I grew familiar with in an old Olympus OM-4T. And I got some great pictures. The K3 was miles ahead of the ME-60 or whatever comes stock in the K5.
But recently I've done a couple of photo shoots. Engagement pictures. Some newborn pics. Stuff where timing is everything and sharp focus is critical. Needless to say, my keeper ratio was disappointingly low. Pictures that I thought were in focus were ever so slightly, but ever so critically, out of focus. Despair! I love my lenses (especially the Zeiss 85 (holy man!)), but how could I continue with such a hit or miss keeper ratio?
I thought about it. Selling them. All of them. But, I decided to hold off and purchase the Ec-A. I had done some reading and stumbled across some information on it. It was a microprism spot only. No split prism. This was just fine with me. I always had better results with microprisms anyway. More importantly, it does not use a micro-array of honeycomb shaped lenses, it has a true matte (ground glass) finish. This is huge for anyone using fast primes. It gives a much, much stronger impression of what in focus is. It is like night and day between the K3 and Ec-A.
Now I bought mine off of ebay (uncut) and cut it myself, which was a bit of a harrowing experience, but focusingscreen.com also carries precut ones (provided they are in stock). Either way, if you are in the market for a new screen, I'd put my money on the Ec-A.
You can check out more technical information on the matte area of the Ec-A
here and the more traditional micro-array (often called precision matte)
here.
Last edited by feilb; 11-16-2011 at 08:39 AM.