Pentax K-R Operating Manual page 60

Adjust the viewfinder diopter to suit your eyesight.
If it is difficult to see the viewfinder image clearly, slide the diopter
adjustment lever sideways.
You can adjust the diopter from approximately -2.5 to +1.5 m-1 .
1
Look through the viewfinder and l_._
slide the diopter adjustment
lever left or right. ,
/ _ff
Adjust the lever until the AF frame in the _-":-:_
viewfinder is focused, k{ \_._',
o,nttheoa era at awhitewa,, orother
bright and consistent surface. _'_r _<
AF frame
• The Eyecup FQ is attached to the viewfinder portion when the camera leaves
the factory. Diopter can be adjusted with the Eyecup FQ attached. However.
adjustment is easier with the eyecup removed.
• To remove the Eyecup FQ, pull it out in the
direction of the arrow.
To attach the Eyecup FQ, align it with the
groove on the viewfinder eyepiece and
push it into the position, j_,_0, I
• If it is difficult to see the viewfinder image
clearly even if you use the diopter
adjustment lever, use the optional diopter
correction lens adapter M. However. the
Eyecup FQ must be removed to use this
adapter. (p.323)