Autofocus issues

davidhobbsm · 02-05-2019, 09:17 AM

Hi,

My K3 which I've had for a number of years no seems to be suffering from Autofocus issues. Whilst the camera is focusing correctly on LiveView - for it seems to be backfocussing otherwise. I'm seeing this behaviour with a number of lenses. Is there anything I can do - or does it need to be serviced.

if it does need to be serviced where is the b est place to get this done at areaosnable cost? I'm based in Seattle.

David

labidas · 02-05-2019, 09:31 AM - **1 Like**

Pentax has AF microadjustment available in the menus.
If it just started happening out of the blue, the issue might be somewhere else.
Maybe there's some dust interfering with the focusing? (you have to check the mirror, sub-mirror and AF module).
Additionally, the sub-mirror might have delamination spots which also interfere with the focusing. These can be "removed" temporarily by swiping the sub-mirror softly.

You can also check the screws on your mount and on the lens. Make sure they are tight.

Also, clean the contacts in the camera and on the lens.

If nothing helps or you don't want to risk anything doing yourself, take it to servicing. Can't recommend any place, I'm not from the US.

**twilhelm** · 02-05-2019, 09:38 AM - **1 Like**

Gently clean the mirror box with a rocket blower. Every camera I’ve had from every manufacturer, has developed autofocus issues from dust in the mirror box. Live view uses the sensor to focus whereas when you aren’t in live view, the camera has a small transparent mirror under the main mirror which is part of the auto focus system. Dust and debris on this mirror will affect the focus.

davidhobbsm · 02-05-2019, 09:56 AM

Thanks for your quick responses. I did try using the rocket blower, but hasn't fixed the issue so far. I'll try a more thorough attempt on all of the above suggestions, and report back.

pschlute · 02-05-2019, 05:00 PM - **1 Like**

Originally posted by davidhobbsm

I'll try a more thorough attempt on all of the above suggestions

That means using the "sensor clean" menu of the camera to lift the mirror out of the way so your blower can get access to the AF module. This also means the sensor is exposed so don't prod it with the blower head. Keep the camera mount pointing down at all times.

ps....don't sneeze

labidas · 02-05-2019, 06:35 PM

Originally posted by pschlute

That means using the "sensor clean" menu of the camera to lift the mirror out of the way so your blower can get access to the AF module. This also means the sensor is exposed so don't prod it with the blower head. Keep the camera mount pointing down at all times.

ps....don't sneeze

No need. You can lift the mirror with your fingertip.

**Larrymc** · 02-05-2019, 08:29 PM

The sub mirror behind the main mirror could have debris on it which can cause erratic auto focus problems sometimes focusing sometimes not. If you have doubts about cleaning it you might want to send it for service. As has been said the AF sensor lens needs periodic cleaning for the best AF response.

02-05-2019, 09:17 AM	#1
davidhobbsm New Member Join Date: Oct 2013 Posts: 13	Autofocus issues Hi, My K3 which I've had for a number of years no seems to be suffering from Autofocus issues. Whilst the camera is focusing correctly on LiveView - for it seems to be backfocussing otherwise. I'm seeing this behaviour with a number of lenses. Is there anything I can do - or does it need to be serviced. if it does need to be serviced where is the b est place to get this done at areaosnable cost? I'm based in Seattle. David

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02-05-2019, 09:31 AM - 1 Like	#2
labidas Forum Member Join Date: Apr 2018 Location: Tartu Posts: 82	Pentax has AF microadjustment available in the menus. If it just started happening out of the blue, the issue might be somewhere else. Maybe there's some dust interfering with the focusing? (you have to check the mirror, sub-mirror and AF module). Additionally, the sub-mirror might have delamination spots which also interfere with the focusing. These can be "removed" temporarily by swiping the sub-mirror softly. You can also check the screws on your mount and on the lens. Make sure they are tight. Also, clean the contacts in the camera and on the lens. If nothing helps or you don't want to risk anything doing yourself, take it to servicing. Can't recommend any place, I'm not from the US.

02-05-2019, 09:38 AM - 1 Like	#3
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	Gently clean the mirror box with a rocket blower. Every camera I’ve had from every manufacturer, has developed autofocus issues from dust in the mirror box. Live view uses the sensor to focus whereas when you aren’t in live view, the camera has a small transparent mirror under the main mirror which is part of the auto focus system. Dust and debris on this mirror will affect the focus.

02-05-2019, 09:56 AM	#4
davidhobbsm New Member Join Date: Oct 2013 Posts: 13 Original Poster	Thanks for your quick responses. I did try using the rocket blower, but hasn't fixed the issue so far. I'll try a more thorough attempt on all of the above suggestions, and report back.

02-05-2019, 05:00 PM - 1 Like	#5
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,215	Originally posted by davidhobbsm I'll try a more thorough attempt on all of the above suggestions That means using the "sensor clean" menu of the camera to lift the mirror out of the way so your blower can get access to the AF module. This also means the sensor is exposed so don't prod it with the blower head. Keep the camera mount pointing down at all times. ps....don't sneeze

02-05-2019, 06:35 PM	#6
labidas Forum Member Join Date: Apr 2018 Location: Tartu Posts: 82	Originally posted by pschlute That means using the "sensor clean" menu of the camera to lift the mirror out of the way so your blower can get access to the AF module. This also means the sensor is exposed so don't prod it with the blower head. Keep the camera mount pointing down at all times. ps....don't sneeze No need. You can lift the mirror with your fingertip.

02-05-2019, 08:29 PM	#7
Larrymc Site Supporter Join Date: Jun 2014 Location: Mississippi, USA Posts: 5,252	The sub mirror behind the main mirror could have debris on it which can cause erratic auto focus problems sometimes focusing sometimes not. If you have doubts about cleaning it you might want to send it for service. As has been said the AF sensor lens needs periodic cleaning for the best AF response.