rolly wheel next to viewfinder ( e-510)

[Kofman13]

i have an olympus e-510 and first day i had it i was fumbling about and turned the jog wheel on the right side of the viewfinder. didnt really change much. i made the view finder a tiny bit out of focus.... whats it do and what did i do by turning it?

 

[Big]

It's the dioptric knob to adjust to people's personal vision. For example, if you wore glasses, it would be adjusted differently than mine since I don't wear any.
If you look real close there should be a notch where "normal" would be I guess. If you moved it, just adjust it back to where it's comfortable to your eyes.