What is the litle slide button for???

Next to the view finder to the left there is a control button it slides up and down , read whole manual and cannot figure out what its for ?

That is diopter adjustment. Push it up and down and look through view finder and you fill see it get blurrier or clearer. I just picked the middle and put my glasses on......LASIK at the eye doctor is next years Christmas present for me,

I tried it last night kind of like an adjustment for someone that was going to take glasses off I think however with my coke bottle glasses it did not at all take enough of the blur out.

It is in the book look for the above in the index you will find.

See you