Sometimes and sometimes.
If it is bright out and your eyepiece covers your eye, you can make out some
detail...enough to aim with.
If the mirror is properly sealed you aren't using internal metering, you
shouldn't need to caver it
at least on Canon 630's
andy schmitt
-Original
Can one see thru the prism/viewfinder on an SLR with a pinhole drilled
body cap?
principally: yes. but you need a considerable amount of light.
Does one need to cover the eyepiece on an SLR conversion to prevent
stray light entering thru the eyepiece?
Depends on the quality of the camera
