[niceshot]

Thanks for that thought. Yes the pair of gold pins are elevated and do recede down when pressure is place on them...just like the other K3 body I own... Maybe there is a connector behind them that I can't see, but getting in that far into the body looks pretty involved.

I think you will find out the manual/auto focus switch is the culprit. It is probable not fully engaging there for fooling the electronics circuitry of the camera.

[photogem]

Thanks! I do have a Sigma HSM 8-16 and 70-200 and they both work. Any suggestions?

Now, the 8-16 for sure is HSM. It is clear then that lenses with an inbuilt motor do work.

But there exist four Sigma 70-200's for Pentax, it is always good to be really clear which one it is because 2 of those have HSM as well!
You see this on the contacts as well, all lenses with an internal motor such as the Sigma HSM's do have those additional 2 contacts as shown HERE on the far right sight (2 gold plated square contacts)


But if it is a Sigma screwdrive lens and it works (which is really strange because those 2 Sigma lenses have a lot of elements and material to be moved by the motor) then only an expert can search further

[waynetc]

Now, the 8-16 for sure is HSM. It is clear then that lenses with an inbuilt motor do work.

But there exist four Sigma 70-200's for Pentax, it is always good to be really clear which one it is because 2 of those have HSM as well!
You see this on the contacts as well, all lenses with an internal motor such as the Sigma HSM's do have those additional 2 contacts as shown HERE on the far right sight (2 gold plated square contacts)


But if it is a Sigma screwdrive lens and it works (which is really strange because those 2 Sigma lenses have a lot of elements and material to be moved by the motor) then only an expert can search further

thanks for the info. My copy of the Sigma 70-200 states Sigma apo DG 70-200 1:2.8 II Macro HSM on it, has a label on it that states EX SIGMA and has the AF/MF switch on the side, so I'm pretty sure it has the screw drive option. Best Regards.

[photogem]

thanks for the info. My copy of the Sigma 70-200 states Sigma apo DG 70-200 1:2.8 II Macro HSM on it, has a label on it that states EX SIGMA and has the AF/MF switch on the side, so I'm pretty sure it has the screw drive option. Best Regards.

The switch on the side has zero to do with your problem.
As you can clearly see, it is an HSM lens and thus it has it's own HSM motor inside.
So it is not screwdrive!


So HSM, SDM and DC Motor lenses work but screwdrive lenses don't work:
Obviously a problem with the screwdrivemotor and to be sent it for repair.

[waynetc]

Sorry for the confusion - I thought HSM meant screw drive. Lenses that do not work are Pentax 55-300 DA 4-5.8, 35 2.4, 50 1.8, Macro 50 2.8 and Tamron 10-24 3.5-4.5 Di SP. Lenses that do work are the Sigma DG 70-200 1:2.8 II Macro HSM and 8-16 4.5-5.6 HSM DC.

[photogem]

Sorry for the confusion - I thought HSM meant screw drive. Lenses that do not work are Pentax 55-300 DA 4-5.8, 35 2.4, 50 1.8, Macro 50 2.8 and Tamron 10-24 3.5-4.5 Di SP. Lenses that do work are the Sigma DG 70-200 1:2.8 II Macro HSM and 8-16 4.5-5.6 HSM DC.

So it is either the mechanism of your K3 or the screwdrive-motor: Repair!
If the screwdrive-rod moves in and out when you change the M-AF-switch, then the switch itself is alright!

M-AF-switch:
https://www.pentaxforums.com/forums/attachments/172-pentax-k-3-k-3-ii/570826...prestigeaf.jpg

Rod (top arrow):
https://www.pentaxforums.com/forums/members/85274-photogem/albums/13024-sole...ture127236.jpg

a thread with a similar problem:
https://www.pentaxforums.com/forums/172-pentax-k-3-k-3-ii/440903-mysterious-...f-problem.html
when it was the switch (note the mentioning of this noice like a food-processor in the last post!)

[niceshot]

So it is either the mechanism of your K3 or the screwdrive-motor: Repair!
If the screwdrive-rod moves in and out when you change the M-AF-switch, then the switch itself is alright!

M-AF-switch:
https://www.pentaxforums.com/forums/attachments/172-pentax-k-3-k-3-ii/570826...prestigeaf.jpg

Rod (top arrow):
https://www.pentaxforums.com/forums/members/85274-photogem/albums/13024-sole...ture127236.jpg

a thread with a similar problem:
a mysterious k3 af/mf-problem... - PentaxForums.com
when it was the switch (note the mentioning of this noice like a food-processor in the last post!)

I told him this already, best thing for him to do is pack it up and send to Precision.

[waynetc]

Thank you all so much for the help on this! I agree that without me taking the camera apart further (I did remove the mount ring to inspect and test the mechanics and swapped that with the ring from the other K3) there is nothing more to do except send it out. I'll update here once it is looked at.

[waynetc]

Let me throw this out there to see what anyone thinks as I get ready to start a deep dive into this K3 or before I send it out or trade it in.

I've watched the video that was kindly posted in this thread.


Here's what we know - HSM lenses work, anything else needs to be focused manually.

When I first turn the camera on I hear the AF motor in the body activates with for example a 50mm DA lense.

Try to take a shot and no sound from AF motor, I can focus manually, see the red dot and hear the beep, then activate the shutter (in AF)


When I place the camera into live view and move the camera around I hear the AF motor in the body as I move the camera to what would require different focal lengths motor responds - nothing changes in where the lens is focused.

So I wonder if what I think is a rod that rotates as the motor activates is not actually turning as the motor moves. I wonder if that rod is secured in that motor with a set screw? The spring load tab that would actually move the focal length of the lens moves freely. Note that if I watch that tab when I first turn the camera on that tab on the rod does not move...if I do the same on the working K3 the tab slightly 'jiggles' on power up. I wish I had a diagram inside the body!


Any thoughts?

[photogem]

So it is either the mechanism of your K3 or the screwdrive-motor: Repair!
If the screwdrive-rod moves in and out when you change the M-AF-switch, then the switch itself is alright!

M-AF-switch:
https://www.pentaxforums.com/forums/attachments/172-pentax-k-3-k-3-ii/570826...prestigeaf.jpg

Rod (top arrow):
https://www.pentaxforums.com/forums/members/85274-photogem/albums/13024-sole...ture127236.jpg

a thread with a similar problem:
a mysterious k3 af/mf-problem... - PentaxForums.com
when it was the switch (note the mentioning of this noice like a food-processor in the last post!)

I told him this already, best thing for him to do is pack it up and send to Precision.

To Precision?

All I read here in this forum about Precision doesn't that great to me.


Anyway: You didn't tell him here in this thread to send his K3 in to precision.
So I don't quite understand why you wrote this?
Maybe I missed something?

[photogem]

Any thoughts?

This is the lever moved by another motor in the K3 for diaphragma-control!

Has nothing to do with the screwdrive motor!

[waynetc]

This is the lever moved by another motor in the K3 for diaphragma-control!

Has nothing to do with the screwdrive motor!

Thank you - I'm just guessing as I go here.. Let me ask one more (what may be a stupid) question.. do all AF lenses have a motor in them and the contacts in the body send a signal to the lens to move the focal length?

[niceshot]

To Precision?

All I read here in this forum about Precision doesn't that great to me.


Anyway: You didn't tell him here in this thread to send his K3 in to precision.
So I don't quite understand why you wrote this?
Maybe I missed something?

No is told i him is is probable the linkage in the maul auto focus switch, to which he said it is a little beyond his skill set. SO that is why ok with you???

[photogem]

Thank you - I'm just guessing as I go here.. Let me ask one more (what may be a stupid) question.. do all AF lenses have a motor in them and the contacts in the body send a signal to the lens to move the focal length?

no, only lenses which have SDM + SM or Pulse or DC-motors.
You recognize those lenses having those 2 additional contacts.

Most Pentax AF lenses just have the screwdrive mechanism inside them but no motor.

[waynetc]

no, only lenses which have SDM + SM or Pulse or DC-motors.
You recognize those lenses having those 2 additional contacts.

Most Pentax AF lenses just have the screwdrive mechanism inside them but no motor.

Thanks again - If the lens has the screw drive mechanism to propel autofocus (for example the 55 - 300 DA HD ED WR) what in the camera body moves the glass inside the lens

I probably did not properly describe my skill level..I'm not 'that' bad The video posted was a great guide... Here's the body opened up. I found no loose ribbon cables or broken wires. At this point it's all back together again and the original problem remains, otherwise it works as before. Any specific place I should look? The lever with the spring under it on the left side near the ring works fine when the AF / M switch is toggled. I'd open it up again if there is something I should take a harder look at.