Diopter adjustment

Soldato
Joined
23 Jul 2009
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I noticed the other day that I was having trouble focusing with my viewfinder and that the image wasn't sharp to my eyes unless I really squinted.

The display all looks pin sharp (that's how I originally set it) but the image isn't unless it's a close object. If I'm focusing on a distant object (10ft or more) then I have to set the diopter 7 clicks from the left for it to look sharp, but then close up objects don't look as sharp when I focus on them.

I assumed that the image I was looking at in the viewfinder was on one 2d plane, so I can't understand why this would be, unless this isn't the case and I'm just a bit short-sighted?

I do spend all day using a pc at work so maybe my eyes are just a bit tired, and it seems less of an issue when it's bright out (viewfinder is a bit dim on my 550d).

Anyone know what I need to do? For now I just have to trust my autofocus.
 
About a year or two ago. I was thinking along the same lines myself. I think it may be a combo of eye-fatigue and spending so much time in front of a monitor that I'm becoming short-sighted.

The only thing I thought was odd was that the diopter adjustment was a compromise. I thought once it was set correctly everything would look sharp if it was in focus, regardless of whether it was close up or far away. The setting I have now (7 clicks clockwise) seems to be perfect for mid-to long distance, but if I'm doing a macro shot it looks slightly blurry and is much sharper at 0-2 clicks from the left.
 
I thought that you set the dioptre adjustment so the focusing screen is in focus, not the subject and changing what you are focusing on should make no difference.

That way if you can focus on the focusing screen OK, you can set the focus of your subject properly.
 
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