Diopter adjustment

dilip1234

My doubt may appear silly, and if found, so kindly excuse me. I have doubt whether the diopter in the camera needs to be adjusted at all on modern DSLR's.
During the pre digital days, you had to see through the view finder, adjust the lens manually until the image is perfectly sharp and then take the picture. There were no lights or beeps to let you know the camera had been focused - everything was manual. If the diopter was not aligned to the optical perfection of the photographer, the camera would also be seeing what the person did, and one would end up with an image that was out of focus.
Now we have intelligent cameras that when the focus is right, the circular light blinks in the view finder, and during auto focus a beep confirms the fact. It is irrelevant how you see through the view finder.
So while taking pictures using a modern DSLR, does the perfect adjustment of diopter in any way affect the sharpness of the picture?
I welcome expert views.

bruto

No, the diopter adjustment affects only the eyepiece, and the auto focus sees through its own system, so it will be as accurate as it's adjusted to be whether or not you see clearly.

This was actually true before, except that viewing was the quickest way to confirm focus. Back in the old days you could set a lens to hyperfocal distance (middle of the infinity mark on the hash mark for the chosen aperture) and get focus even if the viewfinder was broken. Cameras with no rangefinder could be zone focused using the distance scale on the lens.

The only real function of the diopter is for the convenience of the user, and to make manual focusing more accurate. The focus confirmation dot will only light for the chosen auto focus spot, and though pretty good it's not perfect with manual lenses, so it's good to have as sharp a viewfinder view as you can get, especially given how marginal the image is on low end DX finders to start with.

Also, of course, the diopter influences how clearly you see the printed info in the screen, so it's a good idea to adjust it at least well enough to see the focus confirmation dot! I'm pretty far sighted and use a magnifying eyepiece in part because it increases the positive diopter past the cheesy .5 my D3200 offers.

dilip1234

Thanks Bruto. Now it is very clear and my doubt is cleared. Have a good day.