18-135mm autofocus only works in liveview

**HeavyCorPhotography** · 05-16-2021, 10:45 AM

I've got a brand new K-70, less than 500 photos through it so far. Any other lens I've put on the camera has worked just fine, but I recently picked up a used 18-135mm DA WR lens and the autofocus only locks in live view.

With live view off (just looking through the view finder like normal), when it tries to autofocus, it goes back and forth, never locks and beeps at me and usually stops just out of focus.

I've already tried cleaning the contacts and that hasn't helped. Wondering if there's anything else I can troubleshoot to try and fix the problem.

I'm probably not going to bother sending it for repairs, because it still technically works. But it's still a bummer. Since I got it used off someone online, there's no sending it back.

**caliscouser** · 05-16-2021, 11:18 AM

Try different distances, 5ft, 10ft, 20ft, distance. Different focal lengths, 18, 50, 135. Any patterns, or same in all situations?

**Kevin B123** · 05-16-2021, 12:24 PM - **1 Like**

It should work in both OVF and LV, I think you have dust on the auto focus sensor, I'm not sure where that is but liberal use of a rocket blower into and around the inside of the mirror box may fix it.

Prohibitiory · 05-16-2021, 12:30 PM

Originally posted by Kevin B123

It should work in both OVF and LV, I think you have dust on the auto focus sensor, I'm not sure where that is but liberal use of a rocket blower into and around the inside of the mirror box may fix it.

Good tip!!

stevebrot · 05-16-2021, 12:33 PM

Originally posted by Kevin B123

I think you have dust on the auto focus sensor,

Brand new camera and other lenses AF fine, though not a bad idea though if having PDAF problems in general.

Steve

stevebrot · 05-16-2021, 12:57 PM

Originally posted by HeavyCorPhotography

I'm probably not going to bother sending it for repairs, because it still technically works.

Since other lenses work fine, it is most probably a lens issue. PDAF (viewfinder) and CDAF (live view) work differently with PDAF tending to falter if there are issues with the light pathway to the AF sensor (per @Kevin B123; comment above) or optical issues with the lens itself.

Does this happen at all focal lengths and focus distances?

What are the other lenses that are working fine?

Steve

C_Jones · 05-16-2021, 01:35 PM

You may want to try the lens on another Pentax camera to see if you get the same results. If it works on another camera, then it may be your camera that has a connection issue.

**HeavyCorPhotography** · 05-16-2021, 02:47 PM

Originally posted by C_Jones

You may want to try the lens on another Pentax camera to see if you get the same results. If it works on another camera, then it may be your camera that has a connection issue.

It has the same issue on my K-50 (My only other AF Pentax)

Originally posted by stevebrot

Since other lenses work fine, it is most probably a lens issue. PDAF (viewfinder) and CDAF (live view) work differently with PDAF tending to falter if there are issues with the light pathway to the AF sensor (per @Kevin B123; comment above) or optical issues with the lens itself.

Does this happen at all focal lengths and focus distances?

What are the other lenses that are working fine?

Steve

I've been doing some more testing. Up to 50mm the AF will lock through the viewfinder. At 50mm it struggles a little bit, but does eventually focus. Anything over 50mm won't lock the AF, and searches back and forth before stopping.

stevebrot · 05-16-2021, 04:24 PM

Originally posted by HeavyCorPhotography

It has the same issue on my K-50 (My only other AF Pentax)

Looks like it is the lens.

Originally posted by HeavyCorPhotography

I've been doing some more testing. Up to 50mm the AF will lock through the viewfinder. At 50mm it struggles a little bit, but does eventually focus. Anything over 50mm won't lock the AF, and searches back and forth before stopping.

I suspect there is misalignment in that portion of the zoom range that results in an ambiguous pattern to the PDAF sensor. You may want to test the lens for centering defect at the longer end of its range.

If return is not an option, perhaps partial or full refund from the seller?

Steve

**DWS1** · 05-16-2021, 05:24 PM

Sounds like a lens problem.

**HeavyCorPhotography** · 05-16-2021, 07:45 PM

Originally posted by stevebrot

I suspect there is misalignment in that portion of the zoom range that results in an ambiguous pattern to the PDAF sensor. You may want to test the lens for centering defect at the longer end of its range.

If return is not an option, perhaps partial or full refund from the seller?

Steve

I'm gonna try contacting the guy I got it from, but I'm not super hopeful. Kind of what happens trying to go the cheap route sometimes.

**photogem** · 05-16-2021, 08:49 PM

Send the lens back, if paid with paypal you have some chance!

sbc · 05-17-2021, 03:21 AM

I encountered an opposite problem with one of my earlier 16-85s. It would only AF in OVF and not LV. I returned it to B&H for a fully functioning one.

peggers · 05-17-2021, 04:17 AM

Don't forget the basics. Make sure all the contacts are clean. Maybe also get a screwdriver and check that all the screws are nice and tight too.

**HeavyCorPhotography** · 05-17-2021, 02:59 PM

good news is, I looked back through his listing that I had saved, and he does have a 30 day no question return policy. So I've contacted him to get it sent it back. Sucks that it didn't work out because I was really excited for this lens, but at least the seller is accepting returns.

05-16-2021, 10:45 AM	#1
HeavyCorPhotography Site Supporter Join Date: May 2015 Photos: Albums Posts: 82	18-135mm autofocus only works in liveview I've got a brand new K-70, less than 500 photos through it so far. Any other lens I've put on the camera has worked just fine, but I recently picked up a used 18-135mm DA WR lens and the autofocus only locks in live view. With live view off (just looking through the view finder like normal), when it tries to autofocus, it goes back and forth, never locks and beeps at me and usually stops just out of focus. I've already tried cleaning the contacts and that hasn't helped. Wondering if there's anything else I can troubleshoot to try and fix the problem. I'm probably not going to bother sending it for repairs, because it still technically works. But it's still a bummer. Since I got it used off someone online, there's no sending it back.

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05-16-2021, 11:18 AM	#2
caliscouser Site Supporter Join Date: Sep 2014 Location: SF Bay Area, CA Photos: Albums Posts: 1,037	Try different distances, 5ft, 10ft, 20ft, distance. Different focal lengths, 18, 50, 135. Any patterns, or same in all situations?

05-16-2021, 12:24 PM - 1 Like	#3
Kevin B123 Loyal Site Supporter Join Date: Jul 2016 Location: Hampshire Photos: Gallery \| Albums Posts: 3,176	It should work in both OVF and LV, I think you have dust on the auto focus sensor, I'm not sure where that is but liberal use of a rocket blower into and around the inside of the mirror box may fix it.

05-16-2021, 12:30 PM	#4
Prohibitiory Pentaxian Join Date: Jan 2020 Location: Buckinghamshire, UK Posts: 471	Originally posted by Kevin B123 It should work in both OVF and LV, I think you have dust on the auto focus sensor, I'm not sure where that is but liberal use of a rocket blower into and around the inside of the mirror box may fix it. Good tip!!

05-16-2021, 12:33 PM	#5
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Kevin B123 I think you have dust on the auto focus sensor, Brand new camera and other lenses AF fine, though not a bad idea though if having PDAF problems in general. Steve

05-16-2021, 12:57 PM	#6
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by HeavyCorPhotography I'm probably not going to bother sending it for repairs, because it still technically works. Since other lenses work fine, it is most probably a lens issue. PDAF (viewfinder) and CDAF (live view) work differently with PDAF tending to falter if there are issues with the light pathway to the AF sensor (per @Kevin B123; comment above) or optical issues with the lens itself. Does this happen at all focal lengths and focus distances? What are the other lenses that are working fine? Steve

05-16-2021, 01:35 PM	#7
C_Jones Pentaxian Join Date: Sep 2012 Location: NY Photos: Gallery \| Albums Posts: 6,088	You may want to try the lens on another Pentax camera to see if you get the same results. If it works on another camera, then it may be your camera that has a connection issue.

05-16-2021, 02:47 PM	#8
HeavyCorPhotography Site Supporter Join Date: May 2015 Photos: Albums Posts: 82 Original Poster	Originally posted by C_Jones You may want to try the lens on another Pentax camera to see if you get the same results. If it works on another camera, then it may be your camera that has a connection issue. It has the same issue on my K-50 (My only other AF Pentax) Originally posted by stevebrot Since other lenses work fine, it is most probably a lens issue. PDAF (viewfinder) and CDAF (live view) work differently with PDAF tending to falter if there are issues with the light pathway to the AF sensor (per @Kevin B123; comment above) or optical issues with the lens itself. Does this happen at all focal lengths and focus distances? What are the other lenses that are working fine? Steve I've been doing some more testing. Up to 50mm the AF will lock through the viewfinder. At 50mm it struggles a little bit, but does eventually focus. Anything over 50mm won't lock the AF, and searches back and forth before stopping.

05-16-2021, 04:24 PM	#9
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by HeavyCorPhotography It has the same issue on my K-50 (My only other AF Pentax) Looks like it is the lens. Originally posted by HeavyCorPhotography I've been doing some more testing. Up to 50mm the AF will lock through the viewfinder. At 50mm it struggles a little bit, but does eventually focus. Anything over 50mm won't lock the AF, and searches back and forth before stopping. I suspect there is misalignment in that portion of the zoom range that results in an ambiguous pattern to the PDAF sensor. You may want to test the lens for centering defect at the longer end of its range. If return is not an option, perhaps partial or full refund from the seller? Steve

05-16-2021, 05:24 PM	#10
DWS1 Site Supporter Join Date: Aug 2018 Location: Arkansas, USA Posts: 1,169	Sounds like a lens problem.

05-16-2021, 07:45 PM	#11
HeavyCorPhotography Site Supporter Join Date: May 2015 Photos: Albums Posts: 82 Original Poster	Originally posted by stevebrot I suspect there is misalignment in that portion of the zoom range that results in an ambiguous pattern to the PDAF sensor. You may want to test the lens for centering defect at the longer end of its range. If return is not an option, perhaps partial or full refund from the seller? Steve I'm gonna try contacting the guy I got it from, but I'm not super hopeful. Kind of what happens trying to go the cheap route sometimes.

05-16-2021, 08:49 PM	#12
photogem Site Supporter Join Date: Apr 2015 Posts: 3,520	Send the lens back, if paid with paypal you have some chance!

05-17-2021, 03:21 AM	#13
sbc Pentaxian Join Date: Mar 2008 Photos: Albums Posts: 357	I encountered an opposite problem with one of my earlier 16-85s. It would only AF in OVF and not LV. I returned it to B&H for a fully functioning one.

05-17-2021, 04:17 AM	#14
peggers Senior Member Join Date: Apr 2012 Location: Endeavour Hills, Victoria, Australia Photos: Gallery Posts: 210	Don't forget the basics. Make sure all the contacts are clean. Maybe also get a screwdriver and check that all the screws are nice and tight too.

05-17-2021, 02:59 PM	#15
HeavyCorPhotography Site Supporter Join Date: May 2015 Photos: Albums Posts: 82 Original Poster	good news is, I looked back through his listing that I had saved, and he does have a 30 day no question return policy. So I've contacted him to get it sent it back. Sucks that it didn't work out because I was really excited for this lens, but at least the seller is accepting returns.