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Archive 2011 · Focus Screens
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p.1 #1 · p.1 #1 · Focus Screens

Hello everyone, a long time lurker buy not a big poster, but now I need some advice or info. I am wondering if anyone has any experiences with replacing the standard Focus Screen with a split or prism type? I last used the split with film and it is the one thing I really miss when focussing manually and would like to replace the screen with something in the line of a KatzEye screen. Any info or opinions would be appreciated. Not that it matters I guess but all my digital gear is Canon.Thanks.


Dec 17, 2011 at 10:39 PM
Mike K
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p.1 #2 · p.1 #2 · Focus Screens

As you know the split prism focusing screen can aid in quickly and reliably setting manual focus by lining up a high contrast line on both sides of the split prism. The downside is that with slower lenses (max apertures smaller than f2.8) there can be some change in exposure. With a much slower lens (ie f5.6) half of the split prism will be quite dark, perhaps even obstructing your composition. To a lesser degree this will also happen with an f4 lens. In my experience with a f2.8 zoom, the difference in exposure was usually no more than 1/3 a stop and could easily be fudged with chimping.
For a split prism focusing screen Canon recommends switching the exposure setting from the default evaluative to center weighted averaging. Do not use center spot metering, as it will certainly be inaccurate.


In addition Canon have an EX-S line of focusing screens that have more in/out of focus snap than the default screen. They have the advantage that there is a custom function setting to account for the exposure change.


Dec 18, 2011 at 01:16 AM
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p.1 #3 · p.1 #3 · Focus Screens

Mike K thanks for the info and the links. My concern was the change in exposure and the fact that one side would be dark.I checked out the links and never knew about the EOS focusing Screens, seems like the way to go.Thanks for your help and info.


Dec 18, 2011 at 01:26 AM
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p.1 #4 · p.1 #4 · Focus Screens

What canon body are you using?
Not all the canon bodies have user replaceable screens.
Off the top of my head:
1series . 5d/5d2 . 60/50/40D do .
Rebel , 7D , ( not sure about 20/30D) don't.

The bodies that do mostly have a menu option to choose the focus screen which allows the metering system to compensate. The amount of mope satin is not linear so you can't just add or take away a set amount of compensation.

Also each body that has canon screens have different ones with different code letters. The last letter is the type of screen . The most popular is the 'S' screen which is a matt ground screen (no split or lines ) that allows more precision focus with fast (faster than 2.8) lenses. With slower lenses the screen can be a bit to very dark.

If you have a body that is not user replaceable like the 7D (which is said to have a very bad screen for MF with fast lenses) you can still get screens from the companies listed above. These are generally canon screens that are then recut to fit the different body. (some will add a coating to brighten it up) . This is why they are as expensive as they are.(canon screens are pretty cheap compared to many other genuine canon bits).
Most of the sites have instructions on how to change the screens, but obviously the body won't have a setting for the new screen so your exposures may be all over the place.

Dec 18, 2011 at 09:11 AM

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p.1 #5 · p.1 #5 · Focus Screens

The screen fell out of my T2i, a camera I have disliked from day one (I have since bougth the 7D).I have a number of old MF lenses from film gear (Yashica,Minolta,Pentax) and I have bought the adapters for some of the lenses to adapt to Canon and this is why I am considering replacing the screen.

Thanks for your response and I see I have a little more research to do in deciding what screen I will try, I have far more options than I thought. Maybe I'll get to like the camera?



Dec 18, 2011 at 02:55 PM
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p.1 #6 · p.1 #6 · Focus Screens


This tutorial should give you an idea of the installation that you have to do. It's actually a fairly easy procedure with a steady hand and a pair of tweezers. On the models that Ian mentioned above, Canon's made the process even easier and offers the replacement screens. The ones that you see on the internet are usually modified versions of these.

If your old screen just fell out… you might want to make sure that the mounting bracket ("spring lock" in the above link) is stil around. It holds down the screen, and replacement screens usually don't ship with them.

People (me included) have had variable luck using the cheap ebay focusing screens. I have one in my 20D, which has the same mounting bracket system as yours. the focus screen is off - the camera backfocuses by a touch when the split prism is lined up, but it's still significantly better than when I tried to focus f/1.2 lenses with a stock screen There are ways to fix this, but it involves putting in shims to move the focusing screen position.

If you focus wide open and stop down before the shot, the split prism usually works very well. When I use my 17-85mm f/4-5.6, the situation's a bit different. At f/5.6, half of the prism is fairly dark. Moving your eye up and down helps this, but you always have one side of the circle darkened and it can sometimes be a pain to use.

Dec 20, 2011 at 05:50 PM
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p.1 #7 · p.1 #7 · Focus Screens

Keep in mind that a focusing screen may be easy to install, but you are still noodling around a very delicate area of the camera. My focusing screen from focusingscreen.com came with shims, it took multiple tries with a tripod and a re installation of the screen before I got the focus spot on. I also lost the AF red dots even after ordering the silver dot screen (be aware that their dots are just for show if that is a issue), plus the metering is now a bit fickle with certain lenses.

Dec 20, 2011 at 06:12 PM
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p.1 #8 · p.1 #8 · Focus Screens

. I will take all the advice and decided to have the screen replaced by a camera tech, and they are going to install a Katzeye and make sure it is shimmed right etc. A long ways from a $2 repair, Canon quoted me $182.00 and with the KatzEye I am looking at closer to $300.00.Still probably a lot cheaper than it would cost after I tried to repair it.Thanks to all.

Dec 24, 2011 at 08:42 PM

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