T3i sharpness and diopter

[GWK]

I have a T3i. When I set the diopter so that the autofocus ‘squares’ are sharp (-2 notches from center,on the wheel for me) my pictures are blurry. When I adjust the diopter to +5 “notches” on the wheel, the squares are blurry, but when I focus to the least blurry view I can get with that blurry diopter setting, my pictures are very sharp. Are my eyes or is the camera messed up? (I don’t wear corrective lenses). Thanks.

[cicopo]

The diopter doesn't effect the photo. It's there to allow people like me to see properly without my drug store bought reading glasses, which in general I need to put back on to carefully examine the image on the LCD after taking the photo. Set the diopter so that what you see with the shutter button 1/2 depressed is at it's clearest (after the AF has finished focusing).

[GWK]

Thanks for the reply, Cicopo...If I'm manually focussing, the diopter adjustment  sure seems to have an effect on the photo, as I adjust the lens to match the sharpness that I see in the viewfinder. I'm often shooting wildlife in the woods, where autofocus is often impossible (tree branches, etc.). 

[ebiggs1]

"If I'm manually focussing, the diopter adjustment  sure seems to have an effect on the photo"

It does when you use manual focus.  It does not when you use auto focus.

Modern DSLRs are generally not user friendly for manual focus.  There are MF screens for some models that help.

[GWK]

Thanks ebiggs1. As mentioned, shooting in the woods (owls, etc.,) often requires the selective focus of 'manual', in order to isolate a creature perched in branches, or in marsh grasses. I do believe I'm just outside the diopter adjustment for the normal eye T3i...I'll report on the '-2 dioptric adjustment' piece I ordered for my mildly nearsighted right eye 🙂 . Cheers.

[GWK]

Think I may have resolved…while I don’t wear corrective lenses, I do have an uncorrected ‘ -1.50’ in my right eye. Gonna order a corrective -2.00 dioptric adjustment piece from Canon to see if that gives me better focus/diopter 'sync'.

[cicopo]

When you've had a chance to try it let us know your thoughts.

[GWK]

I'll let you know, cicopo, thanks.

[jrhoffman75]

I believe the T3i has an in camera diopter range of +1 to -3; that should accommodate your vision. The add on diopter is additive; with it on the camera would then be -1 to -5.

I agree with ebiggs1 that manually focusing on the viewfinder groundglass can be difficult depending on the subject. But, there is no physical linkage between the eyepiece and the lens. If the desired subject looks sharp in the viewfinder it will be sharp on the sensor (as long as you don't change anything.)

Something sounds wrong to me. Try testing in conditions where you can both manually and auto focus. If I switch to manual focus on lens and hold down shutter button the focus point lights and beeps when image is visually in focus (when I have the focus squares in focus with diopter). If I then turn diopter everything gets blurry; no amount of lens adjustment changes that. Which is what I would expect.

Is your left eye "normal". What happens if you try with that eye.

Some situations lend themselves to focus-recompose. Choose a single focus point that is close to your desired subject (to minimize required camera motion), place that on the subject, allow camera to auto focus, switch to manual focus and recompose. You could also manually focus and allow the foucus point to light and then recompose.

[GWK]

jrhoffman75....thanks for that. I've been messing with it all morning (and ordered the -2 diopter). Anyway, following your advice, I think things just may be adjusting back my way 🙂   Thanks for your help. I'll have a diopter for my retirement, lol. Cheers.Thanks again.