[AnotherVoice]

Here I am at Rocky Mountain National Park, armed w/ my K-3iii, 300mm f4, and the 1.4 TC, chasing through the terrain looking for a moose. 30 min or so in the cold/wind and it quits autofocusing. I pull the TC. No change. Live view works but very slowly. Swap lenses and the camera works fine. Later, back in the cabin - no change. I put the lens on the K-1ii and it works like a champ. Any suggestions to get it working on the K-3iii again?

[Haenzel]

Here I am at Rocky Mountain National Park, armed w/ my K-3iii, 300mm f4, and the 1.4 TC, chasing through the terrain looking for a moose. 30 min or so in the cold/wind and it quits autofocusing. I pull the TC. No change. Live view works but very slowly. Swap lenses and the camera works fine. Later, back in the cabin - no change. I put the lens on the K-1ii and it works like a champ. Any suggestions to get it working on the K-3iii again?

With what lens did you swap it? Perhaps the batteries had become too cold to deliver enough power for the 300mm?

[jgnfld]

Here I am at Rocky Mountain National Park, armed w/ my K-3iii, 300mm f4, and the 1.4 TC, chasing through the terrain looking for a moose. 30 min or so in the cold/wind and it quits autofocusing. I pull the TC. No change. Live view works but very slowly. Swap lenses and the camera works fine. Later, back in the cabin - no change. I put the lens on the K-1ii and it works like a champ. Any suggestions to get it working on the K-3iii again?

Well on the surface you have a power issue that the cold is bringing out. What were the temps? Did you try cleaning contacts on both with alcohol somewhere warm? Did the state of charge go down drastically as the cold hit the insides after a tiime? (W/o my battery grip w/ the big Pentax battery like the K-3iii uses on, I really notice the state of charge draining away very fast below about -6C with my KP and it is then useless after a few shots w/o replacing the battery with a warm one from an inside pocket which itself will need swapping after a short while. The battery grip, though obviates this well for my purposes.)

[mlag]

I guess you mean the lens with SDM motor for focussing?
The basics
- check/clean lens/camera/extender contacts , especially the two inner that drive focus motor....
- check all (lens and camera) auto manual focus switches, change position to test for bad switch contacts or position.
- focus limiter , set to nearfar/ range accidently (outside is far, testing inside is near?)
- if you test other lenses, test only with lenses with el. motor focus (PLM SDM HSM). Screwdrive focus is different .
- charge battery ( too low voltage sometimes affects focus motors, especially heavy (tele) lenses)
- check in warm circumstances, after lens & camera climatised. Affects also battery...
- ...
- unexpected focus setting on camera ( off center point versus center zone, ..., shutter/ release priority etc...) from earlier session?


Reset camera?
Failed sdm motor seems unlikely because it works on K1....

[nixxo2002]

its a SDM issue . SDM sometimes gives problem in cold weather conditions . it happened to me a few times . SDM need to warm up

[ramseybuckeye]

I agree with mlag's suggestions, and the others thinking the cold is the enemy here, cold hates batteries. Another thing you have to watch with the 300 is that the focus switch is very easy to move without trying, especially when you are wearing gloves. Even if it does work on the other camera, a little dirt or film on the contacts of the lens or the camera can cause this, there can be very slight contact alignment difference from one camera to another, where a slight amount of dirt could affect one, but not the other. So make sure you clean all of those surfaces good.

[kkoether]

I had an issue with my K-3 and DA* 60-250mm lens a number of years ago. The focus got erratic and quit. It turned out the small phillips screws in the lens mount on the camera we slightly loose. I carefully tightened them back up and the problem went away. I can see cold weather opening tolerances and causing a similar issue. Be careful if you do tighten those screws. They are easy to strip. I now occasionally will check them to insure they are tight. My K-3 was a little over 2 years old at that time.

[vimlr007]

Assume this is the DA* 300 ?

My SDM did not die -- but it just seemed sluggish -- converted to screw drive and now it is way better

Takes all the contact power problems and cold SDM problems away as the camera is directly doing the focus through the screw drive !

vimlr007

[AfterPentax Mark II]

As it works on the K-1 II it is more likely the K-3 Mark III died. Or as the K-1 was kept in warm surroundings the battery power was up to scratch. Then the K-3 Mark III just needed to be resuscitated...

[UncleVanya]

Here I am at Rocky Mountain National Park, armed w/ my K-3iii, 300mm f4, and the 1.4 TC, chasing through the terrain looking for a moose. 30 min or so in the cold/wind and it quits autofocusing. I pull the TC. No change. Live view works but very slowly. Swap lenses and the camera works fine. Later, back in the cabin - no change. I put the lens on the K-1ii and it works like a champ. Any suggestions to get it working on the K-3iii again?

What was the other lens that worked on the k3iii?

[AnotherVoice]

The lens that worked on the K-3iii was the D-FA 21mm. I swapped the 300/TC to the K-1 (accepting the vignetting), and ran with the 11-18 on the K-3iii for the rest of the trip. I just got back home and tomorrow will try the (now warm) 300 on the K-3iii with a fresh battery. Hopefully it was just the cold. I'll report back. I appreciate all the help/advice/comments!

[photogem]

If the D-FA 21mm lens worked on your K3-III, it is not the K3-III !!!
The D-FA21 has as well its own motor!

Most likely as many others guessed it: It is the SDM-motor DA*300mm/f4, a common problem and best to be solved by converting it to screw-drive (which is faster but louder).

[vimlr007]

If the D-FA 21mm lens worked on your K3-III, it is not the K3-III !!!
The D-FA21 has as well its own motor!

Most likely as many others guessed it: It is the SDM-motor DA*300mm/f4, a common problem and best to be solved by converting it to screw-drive (which is faster but louder).

I agree -- I found the 300 screw drive AF to be faster than the SDM --- if you are not comfortable converting yourself (and you do need a K-5 to do it I think; as I had) then send to UncleVanya !

[UncleVanya]

I agree -- I found the 300 screw drive AF to be faster than the SDM --- if you are not comfortable converting yourself (and you do need a K-5 to do it I think; as I had) then send to UncleVanya !

Often failing sdm is slow and unsure long before it is dead. In my own testing I see little difference in focus speed between both systems if the sdm is healthy. I have seen weird edge cases where a lens functioned fine until the focus situation was difficult. One lens in particular (50-135) was unable to focus in low light and low contrast scenarios until I converted it. As a control I tested my own working sdm copy of the lens and it has no issues on the same focus targets. Because of this I think sdm gets tarred as far slower than it can be. But without a comparison device with a known good motor, the end user has no way to know that their sdm might be starting the failure journey.

[AnotherVoice]

I just tried the lens K-3iii combination and it appears that the cold/power theory is what happened. They play as well together as ever! Thanks for all the advice and suggestions!