Beattie Screens and Canon 1Ds

I seem congenitally unable to shoot a level horizon, even have some

trouble when using a bubble level. On a separate note, I also

sometimes have trouble focusing manually when my eyes get tired. Since

I like macro, this is a serious matter!

For a long time I've been pondering using a focus screen. As I

understand it, some of these might help with both the problems

above--The ones with a split-image focusing circle in the center AND a

grid of vertical and horizontal lines.

As I understand it, Canon doesn't make a screen for my 1Ds that does

both of the above, but I believe Beattie does. I have this one in mind:

http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=4463&is=REG

To my knowledge I've never even met anyone who actually used one of

these on an autofocus camera, and the day of manual-focus cameras was

before my photographic time. I've done some research on the internet,

but not found a ton of information. I'd appreciate it if anyone can

comment on some things I _THINK_ I know and verify them, and maybe

answer some questions.

As I understand it, I'd have to make an adjustment in the Personal

Functions on my 1Ds to use one of these without exposure compensation.

Am I correct that if I make the PF adjustment, I won't have any

further issues in changing exposure because of the screen?

Am I correct that the Beattie screen linked above will do what I think

it will? Is there a better product?

My understanding is that the split image screens don't work as well

with dim light, so that if I was using (for instance) my 300/4 and a

2x teleconverter or similar f/8 combination, I'd not gain as much

benefit from the screen.

I think I may lose spot-metering with this screen, not sure.

My understanding is that installation of this screen is not terribly

difficult. Am I right?

Anything else I should know or consider? I don't expect this to

magically solve all my problems, but I think it will improve matters.

Do I have realistic expectations?

Any input from people who use or have used these screens is very

appreciated!

Mike, someone else will have to help you with Beattie-specific information, but here's a few points that might help.

1. The screen-dependent setting you are thinking of is CF-0 (on the -3 and -1v, and I assume it is the same on the pro digital bodies. Extra-bright screens use CF-0-0 (becuse this capability came in with the -3 which has an extra-bright screen as standard) and standard screens use CF-0-1. Presumably CF-0-0 will be the best choice for a Beattie screen.

2. Even Canon's own screens with focusing aids or clear centres (split-image, cross-split, microprism, etc.) make some (but, fortunately, not all) metering modes unreliable. Check your documentation. The same presumably applies to Beattie screens.

3. It is not the brightness of the light, or lack of it, that creates a problem with focusing aids like split-image, but the aperture of the lens. If that is too narrow for the angle at which the prisms are cut, then one or the other half of the split will black out, which one depends on exactly where your eye is. Conversely, with wide-aperture lenses and narrow-cut prisms, focusing accuracy is inadequate. In MF days Canon made three versions of the microprism screen to accommodate this. Modern high-end AF bodies have high-precision wide-aperture and low-precision narrow-aperture sensors for exactly the same reason.

It sounds as if you are interested in the narrow-aperture end. You had better talk to Beattie about what they can provide. If they do a selection, you should be able to focus at f/5.6 (the narrow-aperture Canon microprism screen I had in my original F-1, type G, I think, achieved that) but f/8 may be a problem.