Focusing screens

Hi all,
this is more of a questions about preference and accuracy of certain screens than anything else.

The more I play with my 85L wide open, the more I don't trust the AF. This is on an old 1Ds2 so MFA isn't an option. When it hits focus, it's brilliant. But that slight softness when it's off by a little bit annoys me. And I'm happy to MF, but I'd like a screen to give me a better look at what is going on.

So... Ec-A, B, L and S.

I think the main question is going to be which is prefered between Ec-A and Ec-B to be honest.

I think don't the L will be a whole lot of help over the Ec-B.

How dark does the Ec-S actually go on f/4 and narrower lenses? I'll mostly have f/2.8 or faster lenses on, but the 15-30mm and 24-105mm are slower, and the 70-200mm will be with an extender on too so I don't want to have those too dark to be using.

They're also about $70 each over here plus shipping so I don't really want to grab a couple just to try and find out I'm not happy with them.

Any experiences will be greatly appreciated!

The Ec-S is fine with f/4 lenses. I have it permanently installed in one body. It's actually more of a problem with very fast lenses - the spot metering circle can be hard to see.

I do use the stock screen in my other body, which I use with an f/4 + converter (so f/5.6) lens.

I own and have extended experience with an Ec-B split screen and Ec-S screen for improving manual focus accuracy. Ec-B will work with your 1Ds II and when you can find a high contrast line in your target which is vertical or diagonal (crossing the horizontal split image line), its very easy to line up the split image for MF accuracy. A great retro feature and is really accurate! However the split is a small area in the center of the image, so some recompositon may be likely after establishing MF.
Another consideration is that the small circular split area can get quite dark (half of it) when the lens is slower ie slower than f2.8. The smaller, very dark area may change (increase) your exposure, especially with the MF/recompose issue on top of it. I found with an f2.8 aperture the exposure difference was typically very small, on the order of 1/3-1/2 stop. Canon recommends changing the exposure to center weight average, but again, the difference was small with fast lenses, but could be much more with slower lenses. Of course the magnitude of this exposure change will vary with composition.

Ec-S screens were introduced after the 1DSII was released. Notice that it is not listed in the CF 00 list? Cameras designed with the Ec-S screen have an exposure compensation algorithm built in to its screen selection menu which is non-linear, so cannot be simulated with a simple exposure compensation. The light loss at f2.8 is about 1/2 stop, f5.6 about 1 1/3 stop. Of course this light loss due to the focusing screen will tend to over expose your shot. See the table at the bottom of this article
http://photo.net …gital-camera-forum/00GrRY

The Ec-S has a steeper parabola, so snaps into and out of focus more quickly than the standard screen. Thus its more obvious you are passing through the point of focus as you turn the focus ring. However there is no definitive cue as to maximal focus. In that regard its like the normal screen.

If accuracy is a priority I would try the Ec-B screen. Ec-S makes finding the focus much faster, easier, but does not aid nearly as much in the accuracy.
Mike K

Thanks, this is exactly the sort of responses I was after.

And yeah I did notice that the Ec-S wasn't listed which is why I thought I'd enquire a bit further as to experiences using it. It sounds like Ec-B is the way to go