The metal mirror bumper of the MX is spring loaded, and could be out of
alignment if messed with (but you can push it with finger w/o side effect).
The resting position can be adjusted through the slot screw near the metal
arm. However, it should be fixed with threadlock and next to impossible to
turn. If it turns easily, it has been messed with before. Missing washers
between the front assembly and the body is quite common for used Pentax
manual focus bodies. It causes wide angle lenses focus past infinity (24mm
or wider becomes very noticeable). Something to check when buying used.
Alan Chan
http://www.pbase.com/wlachan
I'm probably opening mself up for a flogging but here goes:
I've had only one camera so far that didn't focus properly,
by that I mean in-focus in the viewfinder wasn't in-focus on film.
That was an MX, and it was off by a mile.
What I wound up doing was re-shimming the mirror/lens mount
assembly where it attaches to the body.
It had been apart before and apparently some of the shims
had been replaced in the wrong positions, or omitted.
This was a matter of trial and error.
Here's how I checked it, I have since used this method to test
all my cameras for focus alignment.
I cut a thin piece of "ground glass" to the size of 2 frames
of 35mm film.
I then placed this glass, ground side in at the film plane
with masking tape.
I focus an image on the glass with the shutter open on
"bulb", using an 8x loupe. (Cool huh? A 35mm view camera!)
After closing the shutter I check this focus in the viewfinder.
All of my cameras have passed this test except the mentioned MX.
It took 2 days of off and on messing with this one to get it right.
I work mostly on ME, ME-S and MX bodies, and I can't for the life
of me see how a mirror can be out of alignment without being
actually bent, stops deformed or the mechanism very worn.
I understand the LX can be out because of the rubber bumper
problem but the other cameras don't use this method.
In the ME for example the mirror comes to rest on a solid metal
stop, it would take a LOT of pressure to bend this.
The ones that do have bumpers you simply turn the bumper
around to a "good spot" if it is flattened.
The ist D seems to not have a bumper either.
It of course can't be checked by the ground glass method since
it has no "film plane". Hope mine stays aligned forever!
I would be interested in hearing from others who have actually
seen a mirror out of spec, I haven't.
