[rburgoss]

Not so. A simple and alarming test is to flash a strobe (off camera) at the viewfinder in B-mode or using a PC sync cable. The mirror is not light-tight against the focus screen.


Steve

BTW...neither is the non-WR K-mount...

Of course some light (flash burst) could be seen reaching the mirror at the focus screen side. That is why all the mirror/lens mount /sensor box, its all finished flat black, so no reflections can reach the sensofr causing contrast issues. If you had Anything light colored or even chromed INSIDE the mirror box (even if its a small screw head), it will cause reflections projected over the sensor.

[stevebrot]

Of course some light (flash burst) could be seen reaching the mirror at the focus screen side.

Simply do the test and recant !!!

I suppose I could post a photo, but light leaks through the viewfinder and around the mirror have been a potential issue for all of the 45+ years I have been doing SLR photography. My Ricoh XR-2s has a built-in viewfinder blind as did several other cameras of that vintage. In general, there are not a problem with the camera hand-held, but can be a serious issue when using even moderately higher ISO with a bright light source behind the camera on tripod. That would include off-camera flash or a setting sun or a sun-lit reflection.

The mirror box paint, baffles, and flocking may help a little*, but a direct hit on the sensor from above is well, a direct hit.


Steve

* the baffles and such in the mirror box are intended to dampen internal reflection due to many lenses having an image circle that projects onto the sides of the box.