Pentax 6x7 Manual page 14

Unmounted lenses wh ich have not been put
back into their cases should be handled care-
fully. They should be placed on a level surface
to keep them from falling over or rolling away
and damaging the optical system .
Generally, smaller lenses should be stood on
end with the rear mount capped and facing
upwards as with the three lenses in the center
of the photo. Conversely, the SMC Fish -Eye
Takumar 35mm lens should stand on its rear
lens cap to avoid scratching its proturding
front element. Long telephoto lenses with
12
tripod mounts should be placed lengthwise on
their side ; these will topple if stood upright.
Out-of-focus, blurred photographs are almost
always caused by camera shake which results
from not holding the camera firmly enough .
This tendency is more pronounced at slow
shutter speeds and with long 67 telephotos,
in particular" due to their greater length and
forward center of gravity. Greater care is
needed with these lenses to aviod camera
shake.