Auto focus is won't focus at all and is "jumpy".

liam_wilk · 07-13-2020, 03:03 PM

I am pretty new to the photography world so fair warning!!!

I haven't been able to find any issues like this so I thought I'd post. I have a Pentax kx and it works great except for the auto focus feature. I can hear the motor turn and the picture through the viewfinder will go in and out of focus several times rapidly before stopping (out of focus). It sort of jumps back and forth a few times and can't seem to focus on anything. I have cleaned the sensor and mirror on it - done a couple of other cleaning routines to see if it helps and nothing has. I updated the firmware and reset everything to factory settings as well. I also have another larger zoom lens that came with it and it does the same thing with that.

Maybe I need to clean it better or don't have something calibrated? I would take it to a camera repair shop but those are hard to find. I can try and post a video of it if it would help?

I can't seem to find anything online with the same issue - any help is much appreciated!

**FozzFoster** · 07-13-2020, 03:05 PM

Does it happen both through the viewfinder and in live view?

**pepperberry farm** · 07-13-2020, 03:21 PM

is this a new camera to you?

had it been working and now it won't auto-focus?

is with a specific lens but no other lenses?

dbs · 07-13-2020, 04:00 PM

Hi Liam

What are you and the camera trying to focus on.
By your description I think the auto - focus does not know what to focus on, I believe it works better if it has something with dark and light areas next to each other.
Have you tried to manual focus and if so was that more reliable for you ?

Dave

Not a Number · 07-13-2020, 04:03 PM

Did you clean the autofocus sensor under the mirror?

What settings are you using AF-S or AF-C?

ne! · 07-13-2020, 05:26 PM - **1 Like**

If the focus is racking like this, you may be trying to focus on a subject which is too close to the lens. If you attempt to focus on something far away does the problem persist?

**mikesbike** · 07-13-2020, 09:01 PM

What lens are you using?? Yes, if you are closer to a subject than a distance at which that particular lens is capable of focusing, the system will hunt and not succeed.

As a general rule, the AF system will do a good job as long as it has some subject in its AF points having contrasting elements and/or well-defined edges. It cannot, for example, focus on a blank wall or a clear sky. But all automatic systems can occasionally get it wrong. One of the AF points can grab onto something other than that one intends. The most accurate way to achieve focus is to set the AF points to center-only single-point spot AF, then train the camera on a part of the subject having a clear edge, achieve focus by using the half-press of the shutter button, then holding that half press to freeze that focus, you can move the camera for the composition you really want, then complete the shutter button press to fire the shot. For example, in people shots, such as portraits, using the above technique to focus on an eye, then recomposing to frame the shot, is recommended.

Last edited by mikesbike; 07-13-2020 at 09:09 PM.

liam_wilk · 07-13-2020, 11:29 PM

Fozzfoster- yes it happens with both.

Pepperberry- new camera to me, given as a “hand me down” gift. It does it with both lenses I have (the standard one it comes with and another zoom lens)

As far as focusing on a subject it has never worked with anything: close, far, light, dark it’s all the same. It makes 4 back and forth movements and doesn’t focus on anything.

The manual focus works fine it’s just the auto that seems to be confused. I know how to change the auto focus settings (which I have several times) but nothing works

liam_wilk · 07-13-2020, 11:32 PM

Ne!- yes it does, I’m beginning to wonder if the sensor or something is really dirty? I did a sensor scan where it shows the dust

liam_wilk · 07-13-2020, 11:34 PM

Originally posted by Not a Number

Did you clean the autofocus sensor under the mirror?

What settings are you using AF-S or AF-C?

Yes I did but maybe it needs it again? Not sure I got it all the way right.

edit: I am using AF-S

**ehrwien** · 07-14-2020, 07:35 AM

How exactly did you go about cleaning the inside of the camera (lens, mirror, af sensors)? I personally have never done more than carefully blowing air into it with a rocket air blower, with and without the lens cleaning / mirror up function. Well, actually just last week I noticed a little piece of dust on the mirror itself that wouldn't come off with just the air blower, so I carefully took it off with a soft, clean brush. It's helpful to hold the camera with the opening down while blowing air into it so that any dust that does come loose can fall all the way out. And using something like the O-ICK or comparable sensor cleaning kits is usually only advised when the sensor is really messy and you can't get it clean with an air blower.

liam_wilk · 07-14-2020, 08:37 AM

Originally posted by ehrwien

How exactly did you go about cleaning the inside of the camera (lens, mirror, af sensors)? I personally have never done more than carefully blowing air into it with a rocket air blower, with and without the lens cleaning / mirror up function. Well, actually just last week I noticed a little piece of dust on the mirror itself that wouldn't come off with just the air blower, so I carefully took it off with a soft, clean brush. It's helpful to hold the camera with the opening down while blowing air into it so that any dust that does come loose can fall all the way out. And using something like the O-ICK or comparable sensor cleaning kits is usually only advised when the sensor is really messy and you can't get it clean with an air blower.

I did exactly that. I bought a kit off amazon and used the air blower to clean it out then used the cleaning solution it came with to clean the sensor and mirror. I followed a few tutorials online and even made sure I wasn't breathing right into the open camera.

I will try to clean it again today but just with the air blower.

**pentaxus** · 07-14-2020, 08:50 AM

The AF sensor is on the bottom of the mirror box. Some of the light goes through the big main mirror that you see with the lens off and is directed by a smaller mirror under the main mirror to the AF sensors. Sometimes that mirror gets dirty and has to be carefully cleaned so the AF can work. Sometimes that mirror gets damaged which makes the AF not work. Sometimes the AF sensors get dirty and don't work well. If you carefully lift up the main mirror you can see the smaller mirror underneath. It should flip up under the main mirror when you do that.

liam_wilk · 07-14-2020, 01:38 PM

Originally posted by pentaxus

The AF sensor is on the bottom of the mirror box. Some of the light goes through the big main mirror that you see with the lens off and is directed by a smaller mirror under the main mirror to the AF sensors. Sometimes that mirror gets dirty and has to be carefully cleaned so the AF can work. Sometimes that mirror gets damaged which makes the AF not work. Sometimes the AF sensors get dirty and don't work well. If you carefully lift up the main mirror you can see the smaller mirror underneath. It should flip up under the main mirror when you do that.

Okay so I did that, the camera can raise the mirror for cleaning when I go into settings. I cleaned it again earlier and so far nothing has changed...

---------- Post added 07-14-20 at 01:42 PM ----------

Originally posted by mikesbike

What lens are you using?? Yes, if you are closer to a subject than a distance at which that particular lens is capable of focusing, the system will hunt and not succeed.

As a general rule, the AF system will do a good job as long as it has some subject in its AF points having contrasting elements and/or well-defined edges. It cannot, for example, focus on a blank wall or a clear sky. But all automatic systems can occasionally get it wrong. One of the AF points can grab onto something other than that one intends. The most accurate way to achieve focus is to set the AF points to center-only single-point spot AF, then train the camera on a part of the subject having a clear edge, achieve focus by using the half-press of the shutter button, then holding that half press to freeze that focus, you can move the camera for the composition you really want, then complete the shutter button press to fire the shot. For example, in people shots, such as portraits, using the above technique to focus on an eye, then recomposing to frame the shot, is recommended.

I am using the SMC Pentax DAL 52mm. It's not really a matter of knowing how to use the AF but the motor turning it back and forth rapidly whenever I've tried to use it - which has been a ton. The manual focus works fine just the auto is having issues.

---------- Post added 07-14-20 at 01:44 PM ----------

Originally posted by dbs

Hi Liam

What are you and the camera trying to focus on.
By your description I think the auto - focus does not know what to focus on, I believe it works better if it has something with dark and light areas next to each other.
Have you tried to manual focus and if so was that more reliable for you ?

Dave

Yes the manual focus works fine. As far as what the camera is trying to focus on it doesn't seem to ever matter what it is. It does the same number of "jumps" back and forth and won't focus on anything.

CarlJF · 07-14-2020, 05:23 PM

When you focus manually, does the green hexagon light up in the viewfinder ? If so, it means the AF sensor works fine since the focus confirmation is the same system. Said otherwise, the green hexagon lights up when the AF system detects the focus is ok. If there's a problem with the AF sensor, the green hexagon will not light up.

07-13-2020, 03:03 PM	#1
liam_wilk New Member Join Date: Jun 2020 Posts: 10	Auto focus is won't focus at all and is "jumpy". I am pretty new to the photography world so fair warning!!! I haven't been able to find any issues like this so I thought I'd post. I have a Pentax kx and it works great except for the auto focus feature. I can hear the motor turn and the picture through the viewfinder will go in and out of focus several times rapidly before stopping (out of focus). It sort of jumps back and forth a few times and can't seem to focus on anything. I have cleaned the sensor and mirror on it - done a couple of other cleaning routines to see if it helps and nothing has. I updated the firmware and reset everything to factory settings as well. I also have another larger zoom lens that came with it and it does the same thing with that. Maybe I need to clean it better or don't have something calibrated? I would take it to a camera repair shop but those are hard to find. I can try and post a video of it if it would help? I can't seem to find anything online with the same issue - any help is much appreciated!

07-13-2020, 11:34 PM	#10
liam_wilk New Member Join Date: Jun 2020 Posts: 10 Original Poster	Originally posted by Not a Number Did you clean the autofocus sensor under the mirror? What settings are you using AF-S or AF-C? Yes I did but maybe it needs it again? Not sure I got it all the way right. edit: I am using AF-S Last edited by liam_wilk; 07-14-2020 at 01:43 PM.

07-14-2020, 08:37 AM	#12
liam_wilk New Member Join Date: Jun 2020 Posts: 10 Original Poster	Originally posted by ehrwien How exactly did you go about cleaning the inside of the camera (lens, mirror, af sensors)? I personally have never done more than carefully blowing air into it with a rocket air blower, with and without the lens cleaning / mirror up function. Well, actually just last week I noticed a little piece of dust on the mirror itself that wouldn't come off with just the air blower, so I carefully took it off with a soft, clean brush. It's helpful to hold the camera with the opening down while blowing air into it so that any dust that does come loose can fall all the way out. And using something like the O-ICK or comparable sensor cleaning kits is usually only advised when the sensor is really messy and you can't get it clean with an air blower. I did exactly that. I bought a kit off amazon and used the air blower to clean it out then used the cleaning solution it came with to clean the sensor and mirror. I followed a few tutorials online and even made sure I wasn't breathing right into the open camera. I will try to clean it again today but just with the air blower. Last edited by liam_wilk; 07-14-2020 at 08:43 AM.

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07-13-2020, 03:05 PM	#2
FozzFoster Custom User Title Join Date: Jan 2016 Location: Alberta Photos: Albums Posts: 6,806	Does it happen both through the viewfinder and in live view?

07-13-2020, 03:21 PM	#3
pepperberry farm amateur dirt farmer Join Date: Dec 2014 Location: probably out in a field somewhere... Photos: Gallery \| Albums Posts: 41,678	is this a new camera to you? had it been working and now it won't auto-focus? is with a specific lens but no other lenses?

07-13-2020, 04:00 PM	#4
dbs Pentaxian Join Date: Jun 2010 Location: Clare Valley S A Photos: Albums Posts: 7,563	Hi Liam What are you and the camera trying to focus on. By your description I think the auto - focus does not know what to focus on, I believe it works better if it has something with dark and light areas next to each other. Have you tried to manual focus and if so was that more reliable for you ? Dave

07-13-2020, 04:03 PM	#5
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Did you clean the autofocus sensor under the mirror? What settings are you using AF-S or AF-C?

07-13-2020, 05:26 PM - 1 Like	#6
ne! Forum Member Join Date: Dec 2016 Posts: 57	If the focus is racking like this, you may be trying to focus on a subject which is too close to the lens. If you attempt to focus on something far away does the problem persist?

07-13-2020, 09:01 PM	#7
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,549	What lens are you using?? Yes, if you are closer to a subject than a distance at which that particular lens is capable of focusing, the system will hunt and not succeed. As a general rule, the AF system will do a good job as long as it has some subject in its AF points having contrasting elements and/or well-defined edges. It cannot, for example, focus on a blank wall or a clear sky. But all automatic systems can occasionally get it wrong. One of the AF points can grab onto something other than that one intends. The most accurate way to achieve focus is to set the AF points to center-only single-point spot AF, then train the camera on a part of the subject having a clear edge, achieve focus by using the half-press of the shutter button, then holding that half press to freeze that focus, you can move the camera for the composition you really want, then complete the shutter button press to fire the shot. For example, in people shots, such as portraits, using the above technique to focus on an eye, then recomposing to frame the shot, is recommended. Last edited by mikesbike; 07-13-2020 at 09:09 PM.

07-13-2020, 11:29 PM	#8
liam_wilk New Member Join Date: Jun 2020 Posts: 10 Original Poster	Fozzfoster- yes it happens with both. Pepperberry- new camera to me, given as a “hand me down” gift. It does it with both lenses I have (the standard one it comes with and another zoom lens) As far as focusing on a subject it has never worked with anything: close, far, light, dark it’s all the same. It makes 4 back and forth movements and doesn’t focus on anything. The manual focus works fine it’s just the auto that seems to be confused. I know how to change the auto focus settings (which I have several times) but nothing works

07-13-2020, 11:32 PM	#9
liam_wilk New Member Join Date: Jun 2020 Posts: 10 Original Poster	Ne!- yes it does, I’m beginning to wonder if the sensor or something is really dirty? I did a sensor scan where it shows the dust

07-14-2020, 07:35 AM	#11
ehrwien Site Supporter Join Date: May 2016 Posts: 2,782	How exactly did you go about cleaning the inside of the camera (lens, mirror, af sensors)? I personally have never done more than carefully blowing air into it with a rocket air blower, with and without the lens cleaning / mirror up function. Well, actually just last week I noticed a little piece of dust on the mirror itself that wouldn't come off with just the air blower, so I carefully took it off with a soft, clean brush. It's helpful to hold the camera with the opening down while blowing air into it so that any dust that does come loose can fall all the way out. And using something like the O-ICK or comparable sensor cleaning kits is usually only advised when the sensor is really messy and you can't get it clean with an air blower.

07-14-2020, 08:50 AM	#13
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,313	The AF sensor is on the bottom of the mirror box. Some of the light goes through the big main mirror that you see with the lens off and is directed by a smaller mirror under the main mirror to the AF sensors. Sometimes that mirror gets dirty and has to be carefully cleaned so the AF can work. Sometimes that mirror gets damaged which makes the AF not work. Sometimes the AF sensors get dirty and don't work well. If you carefully lift up the main mirror you can see the smaller mirror underneath. It should flip up under the main mirror when you do that.

07-14-2020, 01:38 PM	#14
liam_wilk New Member Join Date: Jun 2020 Posts: 10 Original Poster	Originally posted by pentaxus The AF sensor is on the bottom of the mirror box. Some of the light goes through the big main mirror that you see with the lens off and is directed by a smaller mirror under the main mirror to the AF sensors. Sometimes that mirror gets dirty and has to be carefully cleaned so the AF can work. Sometimes that mirror gets damaged which makes the AF not work. Sometimes the AF sensors get dirty and don't work well. If you carefully lift up the main mirror you can see the smaller mirror underneath. It should flip up under the main mirror when you do that. Okay so I did that, the camera can raise the mirror for cleaning when I go into settings. I cleaned it again earlier and so far nothing has changed... ---------- Post added 07-14-20 at 01:42 PM ---------- Originally posted by mikesbike What lens are you using?? Yes, if you are closer to a subject than a distance at which that particular lens is capable of focusing, the system will hunt and not succeed. As a general rule, the AF system will do a good job as long as it has some subject in its AF points having contrasting elements and/or well-defined edges. It cannot, for example, focus on a blank wall or a clear sky. But all automatic systems can occasionally get it wrong. One of the AF points can grab onto something other than that one intends. The most accurate way to achieve focus is to set the AF points to center-only single-point spot AF, then train the camera on a part of the subject having a clear edge, achieve focus by using the half-press of the shutter button, then holding that half press to freeze that focus, you can move the camera for the composition you really want, then complete the shutter button press to fire the shot. For example, in people shots, such as portraits, using the above technique to focus on an eye, then recomposing to frame the shot, is recommended. I am using the SMC Pentax DAL 52mm. It's not really a matter of knowing how to use the AF but the motor turning it back and forth rapidly whenever I've tried to use it - which has been a ton. The manual focus works fine just the auto is having issues. ---------- Post added 07-14-20 at 01:44 PM ---------- Originally posted by dbs Hi Liam What are you and the camera trying to focus on. By your description I think the auto - focus does not know what to focus on, I believe it works better if it has something with dark and light areas next to each other. Have you tried to manual focus and if so was that more reliable for you ? Dave Yes the manual focus works fine. As far as what the camera is trying to focus on it doesn't seem to ever matter what it is. It does the same number of "jumps" back and forth and won't focus on anything.

07-14-2020, 05:23 PM	#15
CarlJF Veteran Member Join Date: Sep 2014 Location: Quebec City Posts: 1,185	When you focus manually, does the green hexagon light up in the viewfinder ? If so, it means the AF sensor works fine since the focus confirmation is the same system. Said otherwise, the green hexagon lights up when the AF system detects the focus is ok. If there's a problem with the AF sensor, the green hexagon will not light up.