Canon Ec-S

I switched the focusing screen of my Canon EOS 1D Mark III in order to make it easier to focus manually. I have used various manual focus lenses and all the help for that is welcome. The Canon Ec-S fosucing screen makes it a little easier to use manual focusing. The con is that it makes the viewfinder darker. Changing the screen was easy (clear instructions were provided) and currently keep Canon Ec-S screen on all the time instead of the standard screen.