Old Eyes

[Quiet]

I recently got back into photography with a Rebel T7 (not T7i). All is marvelous until I put one of my old M42 mount manual lenses on it. I just can't focus well on the cut frame viewscreen without a microprism/split image focusing screen.

I can find one of those online for 20-ish dollars but I'm not doing surgery on my new camera and the local Canon dealer told me it won't fit a T7 anyway. The screen in question is advertised as fitting a T5.

Can the dimensions or mounting frame of aT7's viewscreen really be different from all the preceeding "T" iterations before it? I'm kinda passionate about using old glass on this marvelous new camera and would appreciate any help.

[wq9nsc]

I started out in the film with split image focus screen and those truly were great for manual focusing.

If you find a split image focusing screen for your camera check carefully because many of these impact the accuracy of exposure metering.  I looked into one of these when I bought my first 1 series digital back in 2005 and I recall at the time that if you installed that screen you lost the ability to achieve accurate auto exposure in most metering modes.

Rodger

[Quiet]

Wq9nsc, thanks for a caveat that hadn't occured to me. I've been so frustrated with my newly discovered suckiness at manual focusing that I haven't thought beyond it.

But I'd be happy to accept having to compensate for or bracket around wonky exposures in order to get crisp focus. Otherwise, using my Takumars has been a joy in Av mode.

[Waddizzle]

@Quiet,

Unfortunatley, the focusing screens in digital Rebels are NOT user replaceable.   There is not option manual screen made available by Canon.  Any manual focusing screen from a third party manufacturer should be regarded with the highest degree of skepticism.  The only way to replace a focusing screen is to let it be replaced in the factory, and even then there is only one focusing screen for the digital Rebel cameras.

[Quiet]

"there is only one focusing screen for the digital Rebel cameras."

I would think so. Why vary that one simple and cheap component within the same series of mass produced cameras?

Ergo, any aftermarket screen that fits a T5 should work in a T7.

I will call the local repair shop to see if they would install a screen I get online and hand to them. I have no desire to install it myself. I can't imagine a simple non-moving and properly shaped piece of plastic causing any harm beyond the exposure inaccuracy mentioned above.

[Waddizzle]

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@Quiet wrote:

"there is only one focusing screen for the digital Rebel cameras."

I would think so. Why vary that one simple and cheap component within the same series of mass produced cameras?

Ergo, any aftermarket screen that fits a T5 should work in a T7.

I will call the local repair shop to see if they would install a screen I get online and hand to them. I have no desire to install it myself. I can't imagine a simple non-moving and properly shaped piece of plastic causing any harm beyond the exposure inaccuracy mentioned above.

---

Personally, I would not modify the camera.  I recall looking into this when I still had my T5.  When I realized that Canon did not make a manual focusing screen, I gave up on the idea for a couple of reasons.

There is no guarantee that AF would still be operatble.  All indicators suggested that AF would never be the same.  Changing focusing screens on more advanced cameras involves telling the camera what type of focusing screen you are using, and the T5 had no provision for such an accommodation. 

I could not be certain that the manual focusing screen would work with all focal lengths, or aperture settings.  Finally, I looked at how well after market battery grips worked the camera.  Battery grips do not work very well because the camera is not designed for it.

My conclusion was that the focusing screen seemed to be built into a larger overall assembly, which was not designed to be disassembled and reassembled.  There seemed to be some unknown degree of precise calibration involved in its' assembly.  I doubt if the averrage local camera shop "has the right stuff" to redesign the camera.

[Quiet · Accepted solution]

Well argued, Waddizzle. I hereby abandon the focus screen approach pricipally because I don't want to put my autofocus at risk. I could live with exposure silliness and just bracket a lot, but accidentally toasting the AF functionally would leave me with a camera that neither I nor the computer could focus at all.

Thanks.

[kvbarkley]

You can use live view and magnify the image, though I much prefer the viewfinder. 

[Quiet]

"You can use live view and magnify the image, though I much prefer the viewfinder. "

Yes, I've tried that and it's swell indoors but without a hood I'm finding the LCD screen to be utterly useless outdoors. Having an old, heavy telephoto hanging off the front of the camera while peeping through a hood/magnifier on the back seems like a bit much.

I just have to come the rest of the way into the 21st Century and buy more AF lenses. 😄

[jrhoffman75]

"There is no guarantee that AF would still be operatble.  All indicators suggested that AF would never be the same.  Changing focusing screens on more advanced cameras involves telling the camera what type of focusing screen you are using, and the T5 had no provision for such an accommodation. "

The autofocus path has nothing to do with the viewfinder focus screen. The autofocus light path is directed to a sub mirror below the main mirror. 

The reason for the custom setting for some screens is that the difference in light transmission could affect the exposure metering. If more or less light is being transmitted the camera needs to know.