Can my eyepiece be out of focus (Not Diopter!)?

Wilt wrote in post #18161995
The diopter merely puts in-focus or out-of-focus the contents of the viewfinder...the LCD text as well as the image formed on the focusing screen.
Take the lens off the camera and refocus the diopter so that you can best see the a) focus points and the b) center circle (spot area) and the c) in-viewfinder control status displays. All THREE need to be 'in focus' simultaneously, or you have an internal issue with alignment of the focus screen with the SI plate with the control status LCD.
Then put the lens back on, and see how Live View focus coicides (or not) with the viewfinder image of the image on the focus screen.

Okay, I just did that. At the same diopter setting I have been using (down 5 clicks), all three are in focus and tack sharp in the viewfinder.

I focused with auto focus, checked the LCD and it's tack sharp (looks a little blurry through viewfinder.

Next I focused manually so the image in the viewfinder was TACK SHARP. I switched to the LCD and zoomed in - completely blurry.

The LCD and the viewfinder (image on the focus screen) do not coincide at all.

Scott

That confirms that your focusing screen is out of position.
Had it been the mirror, the AF system wouldn't work either.

apersson850 wrote in post #18162025
That confirms that your focusing screen is out of position.
Had it been the mirror, the AF system wouldn't work either.

Yeah, the AF system is working just fine. Sounds like a trip to Canon is inevitable.

Thank you.

I don't know how it's mounted in this camera. I have cameras where the user can replace the focusing screen in a simple way, and these models are completely different. Maybe it's just a loose screw.

I looked closely at it and it appears to be in place and secure. I wonder if it's actually the prism that's loose or out of alignment (that's what CPS said it might be).

rrblint wrote in post #18161898
Most probably it's the focus screen that's out of alignment. It needs to be shimmed. The diopter adjustment will not affect the focus of the image, only the display below the image.

I think I was not clear with this post. Allow me to clarify: The diopter adjustment does not affect the focus of the image on the focus screen, but will of course, make the image on the focus screen appear blurry even if it is in focus. The reason that I brought this up is that someone in a previous post implied that the diopter could affect the actual focus of the image on the focus screen which it cannot.

No, but it can make a sharp image on the focusing screen to seem blurry. I think that's what was intended with the remark.

rrblint wrote in post #18162132
I think I was not clear with this post. Allow me to clarify: The diopter adjustment does not affect the focus of the image on the focus screen, but will of course, make the image on the focus screen appear blurry even if it is in focus. The reason that I brought this up is that someone in a previous post implied that the diopter could affect the actual focus of the image on the focus screen which it cannot.

Yes, I may have misinterpreted your response, since it would absolutely affect the appearance of everything in the viewfinder. Obviously the diopter will not affect the outcome on the sensor, as Wilt explained in greater detail.

In either case, the power of the internet seems to have determined a misaligned focusing screen appears to be at fault.

Colorblinded wrote in post #18162392
Yes, I may have misinterpreted your response, since it would absolutely affect the appearance of everything in the viewfinder. Obviously the diopter will not affect the outcome on the sensor, as Wilt explained in greater detail.

In either case, the power of the internet seems to have determined a misaligned focusing screen appears to be at fault.

It could still be the primary mirror as well. The primary mirror has no impact to AF as some light passes through and reflects down to the AF sensor by the secondary mirror. I'm still voting for the focus screen though.

gjl711 wrote in post #18162399
It could still be the primary mirror as well. The primary mirror has no impact to AF as some light passes through and reflects down to the AF sensor by the secondary mirror. I'm still voting for the focus screen though.

It could, but every time I've run in to something like this it's been the screen. Primary mirror alignment issues have always been weirder than this in the cases I've seen.

Needs service either way, and they'll figure it out.

Yea,I'm going with the focus screen as well.

The first mirror affects manual focus and the second mirror affects AF focus.
When you focus through viewfinder with AF the photos are sharp.
When you focus through viewfinder manually the photos are blurry.
On Nikon D90 (and other Nikon DSLRs also) you have 2 screws and with them you can adjust
the position of both mirrors if the focus is not "spot on".
One screw adjusts manual focus and the other screw adjusts AF focus.
I don't know, how would focusing screen (plastic plate with focusing points) affects manual focus.

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I would say the focus screen needs reshimmed as well.

If the primary mirror isn't stopping in the correct position, then it affects AF as well, since the secondary AF mirror is mounted on the back of the primary one.

If the focusing screen is misaligned it affects how AF is seen in the viewfinder (but not the picture itself) as well as how manual focus is perceived (which will affect the picture).
The focusing screen must be at exactly the same optical distance from the lens mount as the sensor is, or it will not truly represent the focus in the image.

^^^^THIS.