Pentax 645N - Page 63

Notes on Accessories
The following conditions do not allow autofocusing
or manual focusing with the in-focus indicator in the
viewfinder. Use the manual focus mode to focus on
the subject with the aid of the matte field surround-
ing the autofocus frame. See page 58 for manual
focusing.
a) When using special effect filters or “Magic Image
Attachment’.
b) When using Extension Tubes or an Auto Bellows
for close-up photography.
Using A Polarizing Filter
When using an ordinary polarizing filter; the half
mirror incorporated into the autofocus system
reduces the effectiveness of the autofocus function
when used in combination with an ordinary polariz-
ing filter. Use a CIRCULAR POLARIZING FILTER
for proper autofocus operation.