How can I purchase a manual focus screen for my wonderful EOS 7D and Rebel XT?

[RobertTheFat]

I'd start with KatzEye: www.katzeyeoptics.com

I've bought a couple of screens from them, and they were prompt and reliable. Since they make their screens to order, you can choose the grid lines you want. They'll warn you that aftermarket screens for the Rebel series are less satisfactory, as they don't preserve the autofocus points in the viewfinder (although they don't affect the AF function).

[TCampbell]

Canon makes focusing screens for some models -- but not all.  

For example, Canon makes screens for the 1D and 1Ds series, but not the 1D X.  They also make them for the 5D and 5D II but not the 5D III.  They have screens for the 40D, 50D, and 60D, but not the 70D.  The Rebel series do not have optional focus screens.

Part of the reason some of the newest cameras don't have optional focus screens is the transparent LCD screen in the viewfinder on these newer cameras.  I think the 7D was the first camera to get this new feature, but now it's in the 1D X, 5D III, and 70D.  The transparent LCD is not actually "in" the focus screen... it's a layer above it.  

See:  http://www.learn.usa.canon.com/resources/articles/2013/eos1dx_intelligent_viewfinder_display.htmlp

There are third party companies that make optional focus screens, but Canon doesn't make them.  The focus screens on your 7D and Rebel XT were not designed to be customer swappable.

Another consideration is how changing the focus system alters how much light can pass through to the metering system.  On my 5D II (which does support optional focus screens and I have one on mine) you have to go into the custom settings and tell the camera which focus screen is installed or you end up with incorrect metering.  

[RobertTheFat]

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@TCampbell wrote:

Canon makes focusing screens for some models -- but not all.  

For example, Canon makes screens for the 1D and 1Ds series, but not the 1D X.  They also make them for the 5D and 5D II but not the 5D III.  They have screens for the 40D, 50D, and 60D, but not the 70D.  The Rebel series do not have optional focus screens.

Part of the reason some of the newest cameras don't have optional focus screens is the transparent LCD screen in the viewfinder on these newer cameras.  I think the 7D was the first camera to get this new feature, but now it's in the 1D X, 5D III, and 70D.  The transparent LCD is not actually "in" the focus screen... it's a layer above it.  

See:  http://www.learn.usa.canon.com/resources/articles/2013/eos1dx_intelligent_viewfinder_display.htmlp

There are third party companies that make optional focus screens, but Canon doesn't make them.  The focus screens on your 7D and Rebel XT were not designed to be customer swappable.

Another consideration is how changing the focus system alters how much light can pass through to the metering system.  On my 5D II (which does support optional focus screens and I have one on mine) you have to go into the custom settings and tell the camera which focus screen is installed or you end up with incorrect metering.  

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If Canon made a focusing screen for the 50D, it must have been a closely guarded secret. (Mine was one of the early models; maybe the screen just wasn't out yet.) I bought KatzEye screens for my 50D and my XTi, not so much for the focusing aids as for the grid lines. I've always had trouble keeping my cameras level, and the early Canon digitals (the ones I could afford, anyway) had no lines. My 7Ds have lines and focus better, so I've never felt the need for an aftermarket screen. Same with my new 5D3; I can't foresee using manual focus enough to justify the annoyance of worrying about the metering corrections.

But if the OP wants a focusing screen for his 7D, KatzEye does make one.

[TCampbell]

The "Ef-" series...  Ef-A, Ef-D, and Ef-S screens all work with the 40D, 50D, and 60D bodies.

The Ef-A is the factory standard screen.  

The Ef-D is etched with the grid lines.

The Ef-S is the super-fine screen designed for manual focusing and really only intended for use with lenses that are f/2.8 or faster.

I have an EOS System guide which is a couple of years old (so it doesn't have the newest bodies in it) -- but it lists every camera body, every lens, and every accessory Canon made at that time as well as the compatibility.  

[hsbn]

The reason Canon doesn't make screen for 5DMIII and others because those camera focus screen are not exchangeable according to Canon. Yes, people can work around that but to Canon it's more like a modification.

Focus screen is really easy to replace so I am less likely to worry about damage anything. But one thing I notice, switching focus screen may introduce dust inside your viewfinder. It doesn't affect autofocus or image but it's hell annoying. I've send my camera to Canon 3x to clean (when it still had warranty).

[ebiggs1]

Unless you like to, or are familar, with getting tools and your fingers inside the mirror box on a 7D,  DO NOT DO THIS.  It is a bad idea and Canon wil not waranty and damage you might, probably likely, do.  

[RobertTheFat]

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@ebiggs1 wrote:

Unless you like to, or are familar, with getting tools and your fingers inside the mirror box on a 7D,  DO NOT DO THIS.  It is a bad idea and Canon wil not waranty and damage you might, probably likely, do.  

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I don't disagree, but my own experience suggests that Canon isn't entirely averse to 3rd-party screens. When I installed a KatzEye screen in my 50D, the frame lines of the KatzEye didn't line up correctly with the camera's autofocus points. I sent it to KatzEye, who pronounced it a misalignment, often seen on the 50D, of the glass plate displaying the autofocus points. They sent it on to Canon, who fixed it for me under warranty.