[anemone]

I have K-3 with 190k shots taken so there isn't that much to lose.

Only WR lenses behave correctly, all other lenses have some electrical problems. I believe seals tighten the mount enough so it doesn't let lens twist. The mount is too loose and I can twist it as far as the locking pin let lens move. When normally taking photos and supporting lens with my hand I easily get dropped to manual focus mode. Moving the lens a bit helps get back to autofocus.

So far I have tried to clean the contacts with isopropyl-alcohol. And I have measured the mount. It is as flat as my dial indicator can tell. Does anyone have any tricks to tighten the mount and make the electrical contacts better?

Sending the camera to service isn't that cost effective.

[MarkJerling]

I would consider it highly unlikely if the issues you are experiencing are in any way due to a problem with your camera's mount. Can you list the lenses you're having problems with?

[UncleVanya]

Buy the adaptist multimount and replace it? It doesn't have full WR however.

[Not a Number]

There are semi-circular band springs on the camera mount side that add tension to the lens to make it fit snugly. I don't think those can be adjusted though.

Check the mounting screws on the camera body lens mount and make sure they are tight. Don't over tighten them as I think they go into the polycarbonate body and you might strip them.

[BigMackCam]

Don't over tighten them as I think they go into the polycarbonate body and you might strip them.

Good advice, although the K-3 body is magnesium alloy over a steel chassis - no polycarbonate in sight

I routinely wipe down my camera body and lens flanges with a micro fiber lens cloth. Always surprised by the black residue I get from both. Years ago in the middle of an event shoot, my Tamron 28-75 wouldn't work. Cleaned as above and no problem since. Had it happen with a rental 645Z and my 645 FA 8-160, wiped both clean and fixed.

Night before a shoot, always a gear check, in camera card format and flange wipe. Never used any solvents.

[Not a Number]

Good advice, although the K-3 body is magnesium alloy over a steel chassis - no polycarbonate in sight

Based on the damage (see thread linked below) to the mount on a K5ii and length of the screws it doesn't seem to be the screws are anchored into the magnesium chassis.

https://www.pentaxforums.com/forums/114-maintenance-repair-articles/306083-k-...nt-repair.html

[stevebrot]

Only WR lenses behave correctly, all other lenses have some electrical problems.

I would consider it highly unlikely if the issues you are experiencing are in any way due to a problem with your camera's mount. Can you list the lenses you're having problems with?

I concur. If the springs had lost tension, WR lenses would be the first to fail to make contact. I think it would be helpful to find out which lenses are having "electrical problems" and the nature of the electrical problems. Is the body not detecting the data pin (AF lens not detected)? Is there no power to the in-lens motor (power contacts failing) for lenses having that feature? Is there a general failure of the mount contacts (F--- )?

If another body is available, do the affected lenses similarly fail on that body?


Steve

[stevebrot]

Good advice, although the K-3 body is magnesium alloy over a steel chassis - no polycarbonate in sight

Based on the damage (see thread linked below) to the mount on a K5ii and length of the screws it doesn't seem to be the screws are anchored into the magnesium chassis.

https://www.pentaxforums.com/forums/114-maintenance-repair-articles/306083-k-...nt-repair.html

Based on the various cutaway and body breakdown photos available on the Web, I believe it is safe to say that the mount on K-3, as with other contemporary Pentax bodies, screws into the composite material mirror box assembly.

https://www.pentaxforums.com/forums/172-pentax-k-3/241399-cutting-up-k-3-a.html


Steve

[anemone]

Pentax lenses:
18-135 WR works always.
DA 18-55 (no WR) loosest of them all but works most of the time
Sigma lenses:
Sigma 150-500 horrible on tripod
Sigma 70-300 has problems sometimes.
Sigma 18-50 has problems sometimes too

I'll try the microfiber cleaning of the flanges. It's quite understandable how it can make the electrical part fail. Something gets between contacts if flanges or mount isn't clean. Let's see what happens.

[stevebrot]

Sigma 150-500 horrible on tripod

Are you mounting the camera or the lens to the tripod when using this lens.


Steve

[stevebrot]

Pentax lenses:
18-135 WR works always.
DA 18-55 (no WR) loosest of them all but works most of the time
Sigma lenses:
Sigma 150-500 horrible on tripod
Sigma 70-300 has problems sometimes.
Sigma 18-50 has problems sometimes too

I'll try the microfiber cleaning of the flanges. It's quite understandable how it can make the electrical part fail. Something gets between contacts if flanges or mount isn't clean. Let's see what happens.

"Horrible", "problems sometimes", and "electrical part fail" does not mean much. Does this mean that you are not willing to share how these lenses are failing or is there a language problem? If language, perhaps you could share the details in Finnish and we can do our best using available translation tools to figure out what is happening with your camera.

Despite not having much information, here are a few observations:

• I only see one WR lens on your list, so I am going to consider that aspect of the original post unimportant ("red herring")
• It is unclear what is meant by "loose"
  • Do you mean the lens is not held firm to the mount face (wobbles or can be lifted off so that daylight may be seen between the flange faces)? -or-
  • Do you mean that the lens is free to rotate out of registration for the mount contacts (retention pin is not holding lens in place)? -or-
  • Do you mean something else?
• You mentioned AF failures in your original post. Is that true for all the lenses on your list with the exception of the DA 18-135?

Steve

[BigMackCam]

Based on the damage (see thread linked below) to the mount on a K5ii and length of the screws it doesn't seem to be the screws are anchored into the magnesium chassis.

https://www.pentaxforums.com/forums/114-maintenance-repair-articles/306083-k-...nt-repair.html

Based on the various cutaway and body breakdown photos available on the Web, I believe it is safe to say that the mount on K-3, as with other contemporary Pentax bodies, screws into the composite material mirror box assembly.

Indeed, it looks like the mount isn't attached to the chassis itself. I'm sure there must be a good reason for that (something to do with alignment and adjustment, perhaps?), but it seems like a missed opportunity in terms of making the mount robust... maybe, like the wings of an aircraft, there's supposed to be a degree of flexibility to avoid breakage under stress? Interesting... That certainly makes me even less inclined to let a heavier lens dangle un-supported on occasion...

[stevebrot]

but it seems like a missed opportunity in terms of making the mount robust...

There is a whole school of thought around the idea that having the mount as a breakaway part is better than using it as a tool to deform and damage the camera chassis. Even traditional film SLRs use fairly small and shallow screws that easily pull free. That being said, I am not sure that stripping out the mount positions on the mirror box is so great either. Replacement of that unit is not minor and involves significant alignment and calibration tasks.

That certainly makes me even less inclined to let a heavier lens dangle un-supported on occasion...

Yep...I would suggest that one consider whether they would hang said lens from a body piercing as a point of comparison.


Steve

[BigMackCam]

i would suggest that one consider whether they would hang said lens from a body piercing as a point of comparison.

LOL