DA SCM 300MM fr lens- auto focus not working?

Sank63 · 09-17-2022, 08:09 AM

I bought this lens second-hand a few months ago. Had my K-70 body with me to test it. Worked great.
In the last few weeks the auto focus has stopped working. Have tried on my k-70 and k-5 bodies. Have cleaned the contacts, that didn't help.
Having the same problem with a Sigma wide angle lens I bought at the same time.
Any ideas on trouble shooting?

photoptimist · 09-17-2022, 08:32 AM - **1 Like**

Define "stopped working":
* no movement at all,
* hunts unsuccessfully,
* error messages,
* consistently out-of-focus,
* does not work in live view, etc.

**UncleVanya** · 09-17-2022, 11:19 AM

Originally posted by Sank63

I bought this lens second-hand a few months ago. Had my K-70 body with me to test it. Worked great.
In the last few weeks the auto focus has stopped working. Have tried on my k-70 and k-5 bodies. Have cleaned the contacts, that didn't help.
Having the same problem with a Sigma wide angle lens I bought at the same time.
Any ideas on trouble shooting?

It’s odd that both stopped. What’s the sigma model?

On the k-5 and the da 300 lens I assume you have switched the af/mf switches back and forth and both are set to AF?

Do any of your lenses work in autofocus?

Did you turn on back button autofocus and forget? (When I first started using this feature I forgot at least one time and panicked.

**ehrwien** · 09-17-2022, 01:57 PM

If it's not solved by what UncleVanya suggested, could there be dust on the AF sensor on the bottom of the camera?

Sank63 · 09-18-2022, 06:25 PM

Originally posted by photoptimist

Define "stopped working":
* no movement at all,
* hunts unsuccessfully,
* error messages,
* consistently out-of-focus,
* does not work in live view, etc.

Thanks for the quick responses.
- It doesn't hunt it doesn't do anything. The camera message says MF
- I have checked all the different settings, both on the camera and on the lens. When I have it in AF mode, it won't fire until I manually get the focus right.
- In AF mode no problem. I can click away, in focus or not.
- All my other lenses, 100mm DA, 35MM DA, my 55-300 all focus with no problem.
- Sigma lens is 10-20MM F3.5 EX DC HSM

I don't know f this matters, I bought both of them second hand from a local guy. They both worked for a while.

**UncleVanya** · 09-19-2022, 05:01 AM

Originally posted by Sank63

Thanks for the quick responses.
- It doesn't hunt it doesn't do anything. The camera message says MF

That’s odd. I don’t believe I’ve ever seen an sdm failure that said MF. Also the Sigma HSM lens isn’t likely to suffer lens motor failure. Do the sdm contacts appear ok? Honestly this is a really confusing problem.

Originally posted by Sank63

- I have checked all the different settings, both on the camera and on the lens. When I have it in AF mode, it won't fire until I manually get the focus right.
- In AF mode no problem. I can click away, in focus or not.

Did you mean AF in both sentences? Or is one meant to say MF? AF mode with an MF lens triggers “catch in focus” mode. On lenses with physical AF/MF switches, you put the lens switch on MF and leave the body switch on AF to enable this mode.

Originally posted by Sank63

- All my other lenses, 100mm DA, 35MM DA, my 55-300 all focus with no problem.

If that’s a non-PLM 55-300 then all of those lenses are screw drive. The two lenses failing all use the “sdm” type system. The Sigma uses a different motor technology, but it still relies on the sdm contacts and protocols in the camera.

Originally posted by Sank63

I don't know f this matters, I bought both of them second hand from a local guy. They both worked for a while.

Any detail could help but I’m not sure that this one is relevant. Used lenses are typically more prone to failure than new, but this failure is really odd. It feels like a problem with the body.

kkoether · 09-22-2022, 06:18 PM

It's a long shot but check the mounting screws on the mount of your camera's. I've seen and had them become slightly loose and cause focus issues. Especially with longer, heavier lenses. I recently had a friend with a Canon that had the same issue with his long zoom lens. Just be careful tightening them. They are a fine thread and can strip easily. Good Luck.

09-17-2022, 08:09 AM	#1
Sank63 New Member Join Date: Sep 2022 Posts: 3	DA SCM 300MM fr lens- auto focus not working? I bought this lens second-hand a few months ago. Had my K-70 body with me to test it. Worked great. In the last few weeks the auto focus has stopped working. Have tried on my k-70 and k-5 bodies. Have cleaned the contacts, that didn't help. Having the same problem with a Sigma wide angle lens I bought at the same time. Any ideas on trouble shooting?

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09-17-2022, 08:32 AM - 1 Like	#2
photoptimist Pentaxian Join Date: Jul 2016 Photos: Albums Posts: 5,123	Define "stopped working": * no movement at all, * hunts unsuccessfully, * error messages, * consistently out-of-focus, * does not work in live view, etc.

09-17-2022, 11:19 AM	#3
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,403	Originally posted by Sank63 I bought this lens second-hand a few months ago. Had my K-70 body with me to test it. Worked great. In the last few weeks the auto focus has stopped working. Have tried on my k-70 and k-5 bodies. Have cleaned the contacts, that didn't help. Having the same problem with a Sigma wide angle lens I bought at the same time. Any ideas on trouble shooting? It’s odd that both stopped. What’s the sigma model? On the k-5 and the da 300 lens I assume you have switched the af/mf switches back and forth and both are set to AF? Do any of your lenses work in autofocus? Did you turn on back button autofocus and forget? (When I first started using this feature I forgot at least one time and panicked.

09-17-2022, 01:57 PM	#4
ehrwien Site Supporter Join Date: May 2016 Posts: 2,782	If it's not solved by what UncleVanya suggested, could there be dust on the AF sensor on the bottom of the camera?

09-18-2022, 06:25 PM	#5
Sank63 New Member Join Date: Sep 2022 Posts: 3 Original Poster	Originally posted by photoptimist Define "stopped working": * no movement at all, * hunts unsuccessfully, * error messages, * consistently out-of-focus, * does not work in live view, etc. Thanks for the quick responses. - It doesn't hunt it doesn't do anything. The camera message says MF - I have checked all the different settings, both on the camera and on the lens. When I have it in AF mode, it won't fire until I manually get the focus right. - In AF mode no problem. I can click away, in focus or not. - All my other lenses, 100mm DA, 35MM DA, my 55-300 all focus with no problem. - Sigma lens is 10-20MM F3.5 EX DC HSM I don't know f this matters, I bought both of them second hand from a local guy. They both worked for a while.

09-19-2022, 05:01 AM	#6
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,403	Originally posted by Sank63 Thanks for the quick responses. - It doesn't hunt it doesn't do anything. The camera message says MF That’s odd. I don’t believe I’ve ever seen an sdm failure that said MF. Also the Sigma HSM lens isn’t likely to suffer lens motor failure. Do the sdm contacts appear ok? Honestly this is a really confusing problem. Originally posted by Sank63 - I have checked all the different settings, both on the camera and on the lens. When I have it in AF mode, it won't fire until I manually get the focus right. - In AF mode no problem. I can click away, in focus or not. Did you mean AF in both sentences? Or is one meant to say MF? AF mode with an MF lens triggers “catch in focus” mode. On lenses with physical AF/MF switches, you put the lens switch on MF and leave the body switch on AF to enable this mode. Originally posted by Sank63 - All my other lenses, 100mm DA, 35MM DA, my 55-300 all focus with no problem. If that’s a non-PLM 55-300 then all of those lenses are screw drive. The two lenses failing all use the “sdm” type system. The Sigma uses a different motor technology, but it still relies on the sdm contacts and protocols in the camera. Originally posted by Sank63 I don't know f this matters, I bought both of them second hand from a local guy. They both worked for a while. Any detail could help but I’m not sure that this one is relevant. Used lenses are typically more prone to failure than new, but this failure is really odd. It feels like a problem with the body.

09-22-2022, 06:18 PM	#7
kkoether Pentaxian Join Date: Jul 2008 Location: Huber Heights, OH, USA Photos: Gallery \| Albums Posts: 731	It's a long shot but check the mounting screws on the mount of your camera's. I've seen and had them become slightly loose and cause focus issues. Especially with longer, heavier lenses. I recently had a friend with a Canon that had the same issue with his long zoom lens. Just be careful tightening them. They are a fine thread and can strip easily. Good Luck.