Focus problem - is this a fault in the G7 camera

XVOYAGERX wrote:

I f the video is important to you Always` use M/Focus, i never use Auto-Focus even on my GH5, no Auto-Focus system is immune to the `hunting-Bug` even Phase-Detect!!

I know what you mean...If the subject is always a set distance to the camera such as a performer on stage then there should be no reason not to use MF like you suggested.

Brian

hindesite wrote:

What you describe is not a camera fault.

However, you haven't said what lens you are using, and how well the G7 performs AF with different lenses does vary, and especially so for non-DFD lenses.

With quick DFD lenses the disruption to focus is minimal and may not even be noticeable.

I'm using 14-140mm Panasonic lens f3.5 - f5.6 with the stabilizer turned on.

Brian

I took a look at some of my video clips that had the focusing problem and most of the time the subject goes out of focus during zooming while video recording. There are two ways the camera goes out of focus.

1. Focusing while zooming in/out. So one frame will be in focus and the next frame id out-of-fous etc.

2. refocusing after I have zoomed in/out. This is a problem as it can be out of focus for a second or two before it finds the correct focus.

But there are time when I have not zoomed when it goes out of focus, maybe the camera needs to recheck the focus at times. In one case a person held up a card that appeared in center of the frame causing the camera to refocus yet before then someone had moved around the room and the camera dd not go out of focus.

The G7 camera currently has the following setting for video:

AFS/AFF set to AFS

Continuous AF = ON

Metering mode = Focus and measure subject on the center of the screen

MP4  28M/50fps

Brian

Brisn5757 wrote:

I took a look at some of my video clips that had the focusing problem and most of the time the subject goes out of focus during zooming while video recording. There are two ways the camera goes out of focus.

1. Focusing while zooming in/out. So one frame will be in focus and the next frame id out-of-fous etc.

2. refocusing after I have zoomed in/out. This is a problem as it can be out of focus for a second or two before it finds the correct focus.

This information is fairly critical and glad you mentioned it. In this case this is likely normal behavior. This lens is not a true parfocal lens (meaning it doesn't maintain focus during zooming). Panasonic cameras however do "simulate" parfocal in software, but this means the lens has to refocus while you are zooming to try to maintain focus on the subject. It may not always get it right.

The aperture you set it at may matter too depending on how the lens is designed (how the variable max aperture changes). For example setting it at f/5.6 or smaller may help (or it may make it worse than setting at f/3.5 so it is always wide open).

But there are time when I have not zoomed when it goes out of focus, maybe the camera needs to recheck the focus at times. In one case a person held up a card that appeared in center of the frame causing the camera to refocus yet before then someone had moved around the room and the camera dd not go out of focus.

The G7 camera currently has the following setting for video:

AFS/AFF set to AFS

Continuous AF = ON

Metering mode = Focus and measure subject on the center of the screen

MP4 28M/50fps

Brian

This behavior likely has to do with two factors. Given you set focus to center, then the change in the center triggers a refocusing and by holding up a card, the focus plane changed.

In the second case, the person moving around the room may not have moved over the center focus area or even if they did, they may have stayed on the same focus plane (moving across the frame, rather than toward or away from camera).

JakeJY wrote:

Brisn5757 wrote:

I took a look at some of my video clips that had the focusing problem and most of the time the subject goes out of focus during zooming while video recording. There are two ways the camera goes out of focus.

1. Focusing while zooming in/out. So one frame will be in focus and the next frame id out-of-fous etc.

2. refocusing after I have zoomed in/out. This is a problem as it can be out of focus for a second or two before it finds the correct focus.

This information is fairly critical and glad you mentioned it. In this case this is likely normal behavior. This lens is not a true parfocal lens (meaning it doesn't maintain focus during zooming). Panasonic cameras however do "simulate" parfocal in software, but this means the lens has to refocus while you are zooming to try to maintain focus on the subject. It may not always get it right.

The aperture you set it at may matter too depending on how the lens is designed (how the variable max aperture changes). For example setting it at f/5.6 or smaller may help (or it may make it worse than setting at f/3.5 so it is always wide open).

But there are time when I have not zoomed when it goes out of focus, maybe the camera needs to recheck the focus at times. In one case a person held up a card that appeared in center of the frame causing the camera to refocus yet before then someone had moved around the room and the camera dd not go out of focus.

The G7 camera currently has the following setting for video:

AFS/AFF set to AFS

Continuous AF = ON

Metering mode = Focus and measure subject on the center of the screen

MP4 28M/50fps

Brian

This behavior likely has to do with two factors. Given you set focus to center, then the change in the center triggers a refocusing and by holding up a card, the focus plane changed.

In the second case, the person moving around the room may not have moved over the center focus area or even if they did, they may have stayed on the same focus plane (moving across the frame, rather than toward or away from camera).

Thanks for your feedback JackIY.

In the case of the parade I video recorded it was a dull overcast day and from the stills I took while recording the aperture was mostly f3.5 with a shutter speed of 1/250.

In the case of the card that might have caused the camera to refocus. The person was at one stage moving towards the audience and closer to the camera than the card was and there were people standing near by behind the card he had in his hand. But a chance in focal point was worth considering. It may also depend on how long the person is close to the camera before the camera decides to refocus.

Brian

Brisn5757 wrote:

What I'm trying to find out is if I have a fault on my G7 camera or does this normally happen with the G7 camera.

When video recording the focus will change for a moment and what I'm recording goes out of focus. There doesn't seem a reason why the camera should attempt to refocus after it has correctly focused on a subject. There is nothing that becomes near the camera for the change in focus to happen. It can happen once within a 5 minute video clip and goes out of focus for a few seconds. It's enough ruin an important moment.

The camera is set to AFS/AFF

What I need to know is do owners of the G7 camera also have this problem?

If needed I could upload a video clip example.

Brian

Here is an example

https://youtu.be/PAakOpQ6G_I

Can someone see why the camera went out of focus?

Brian

Brisn5757 wrote:

Here is an example

https://youtu.be/PAakOpQ6G_I

Can someone see why the camera went out of focus?

Examples are always useful!

If you look close, there is zooming going on just before the camera loses the focus. I tend to avoid zooming while filming, mainly because it looks "unprofessional".

Another thing is that if there is a lot of shake, then it can be very difficult for the AF algorithm to keep the subject in focus (shaky video is also annoying to watch). The basic idea of contrast-detect auto-focus (CDAF) is that it measures the contrast (sharpness) in the user/camera-defined area(s)*. Then the camera adjusts focus back-and-forth, until the contrast is maximized. This is when the camera assumes that the focus is right.

When the screen is shaking, the contrast at the focus area(s) constantly goes up and down, making it really hard for the camera know if the area is in focus or not. Also, shake causes motion blur to individual frames, so even if they are perfectly in focus, the contrast can be low (and constantly changing).

The AE/AF lock button can be configured to temporarily lock the focus for situations when you suspect that the camera might lost the focus (without moving the AF/MF lever around that button). I prefer to have set the 'AE/AF lock button hold' ON. This way when I press the button once, it locks the exposure/focus until I press the button again.

P.S. If you record audio, then an external physically isolated microphone is recommended, as the internal microphone will record all the sounds when pressing the buttons. Alternatively, the touch screen can be used to change the setting silently.

*What focus method / areas / patterns do you use (left keypad button)? I gave my recommendations for this in earlier post.

pannumon wrote:

Brisn5757 wrote:

Here is an example

https://youtu.be/PAakOpQ6G_I

Can someone see why the camera went out of focus?

Examples are always useful!

If you look close, there is zooming going on just before the camera loses the focus. I tend to avoid zooming while filming, mainly because it looks "unprofessional".

Another thing is that if there is a lot of shake, then it can be very difficult for the AF algorithm to keep the subject in focus (shaky video is also annoying to watch). The basic idea of contrast-detect auto-focus (CDAF) is that it measures the contrast (sharpness) in the user/camera-defined area(s)*. Then the camera adjusts focus back-and-forth, until the contrast is maximized. This is when the camera assumes that the focus is right.

When the screen is shaking, the contrast at the focus area(s) constantly goes up and down, making it really hard for the camera know if the area is in focus or not. Also, shake causes motion blur to individual frames, so even if they are perfectly in focus, the contrast can be low (and constantly changing).

The AE/AF lock button can be configured to temporarily lock the focus for situations when you suspect that the camera might lost the focus (without moving the AF/MF lever around that button). I prefer to have set the 'AE/AF lock button hold' ON. This way when I press the button once, it locks the exposure/focus until I press the button again.

P.S. If you record audio, then an external physically isolated microphone is recommended, as the internal microphone will record all the sounds when pressing the buttons. Alternatively, the touch screen can be used to change the setting silently.

*What focus method / areas / patterns do you use (left keypad button)? I gave my recommendations for this in earlier post.

Thanks pannumon for your reply.

I have other video clips of the parade where I have altered the zoom slightly and it has not effected the focus. I also have a steady shot the I panned as float went past me and there was a refocus by the camera but I think I also slightly altered the zoom for the panning float. I usually use a monopod but as the camera is lighter than my Canon 70D camera I decided to hand hold the camera.

It's difficult to find a pattern as to when refocusing is likely to occur as sometimes I can alter the zoom and it has no effect on the focusing except in some cases the refocusing takes place as I'm altering the zoom then it does not try to refocus when I have finished zooming.

I've used this G7 camera overseas and have not had many refocusing problems. The parade seemed to bring out the worst in the camera for refocusing. Maybe it was due to a lack of light at the time due to being a dull overcast day, as you say it depends on contrast for focusing or maybe due to me turning the camera off a lot during the parade to reduce the use of the battery (50fps seems to use more battery power).

I'm also wondering if it's the speed that I zoom or the amount that I zoom that's causing this refocusing problem.

In my case I moved the camera from a float down to one of the performers shaking hands with the children as soon as the camera left the float it went out of focus but did not change to the correct focus like it normally does a second or so later. So I had a badly focused performer shaking hands.

Brian

Its a darn shame, because the video quality from your G7 is superb, i have the exact same problem with my fz2000, it will hunt every now and again, even when i had it on a beanbag (rock-steady} at a river bank, so darned annoying, i know what you are going through, i have also yet to test my GH5 after i installed the latest firmware, folks have stated it makes one hell of a difference to its focusing, and the G9`s, i really hope so!!...

Thanks for these tips my friend, i must try them out soon, weather at the moment is he**ish here in Scotland!!     

Brisn5757 wrote:

What I'm trying to find out is if I have a fault on my G7 camera or does this normally happen with the G7 camera.

When video recording the focus will change for a moment and what I'm recording goes out of focus. There doesn't seem a reason why the camera should attempt to refocus after it has correctly focused on a subject. There is nothing that becomes near the camera for the change in focus to happen. It can happen once within a 5 minute video clip and goes out of focus for a few seconds. It's enough ruin an important moment.

The camera is set to AFS/AFF

What I need to know is do owners of the G7 camera also have this problem?

If needed I could upload a video clip example.

Brian

Some are saying that zooming is causing the Panasonic Camera to refocus after viewing my first example so I've included this example to say the camera not refocusing when zooming.

Brian

Brisn5757 wrote:

What I'm trying to find out is if I have a fault on my G7 camera or does this normally happen with the G7 camera.

When video recording the focus will change for a moment and what I'm recording goes out of focus. There doesn't seem a reason why the camera should attempt to refocus after it has correctly focused on a subject. There is nothing that becomes near the camera for the change in focus to happen. It can happen once within a 5 minute video clip and goes out of focus for a few seconds. It's enough ruin an important moment.

The camera is set to AFS/AFF

What I need to know is do owners of the G7 camera also have this problem?

If needed I could upload a video clip example.

Brian

Not happy with the focus problem with my G7 camera I did some tests using 45-150mm lens and found it was not the camera but the 14-140mm lens that was causing the problems.

I was able to create the lens refocusing problem by quickly zooming in or out a short zooming amount using the 14-140mm zoom lens. It looks like the lens starts focusing in the wrong direction and keeps focusing for a near object putting the picture completely out of focus then after a short period it starts to focus for a far object and gets the picture in focus again.

I thought at first it was the speed at which the lens focuses but there are times when this lens is able to quickly focus. I also turned off the lens stabilizer to see if it made any difference but it didn't.

If it was the camera at fault then there would be more reports from owners of this camera.

I wonder if camera lens have a software update?

Brian

Brisn5757 wrote:

Brisn5757 wrote:

What I'm trying to find out is if I have a fault on my G7 camera or does this normally happen with the G7 camera.

When video recording the focus will change for a moment and what I'm recording goes out of focus. There doesn't seem a reason why the camera should attempt to refocus after it has correctly focused on a subject. There is nothing that becomes near the camera for the change in focus to happen. It can happen once within a 5 minute video clip and goes out of focus for a few seconds. It's enough ruin an important moment.

The camera is set to AFS/AFF

What I need to know is do owners of the G7 camera also have this problem?

If needed I could upload a video clip example.

Brian

Not happy with the focus problem with my G7 camera I did some tests using 45-150mm lens and found it was not the camera but the 14-140mm lens that was causing the problems.

I was able to create the lens refocusing problem by quickly zooming in or out a short zooming amount using the 14-140mm zoom lens. It looks like the lens starts focusing in the wrong direction and keeps focusing for a near object putting the picture completely out of focus then after a short period it starts to focus for a far object and gets the picture in focus again.

I thought at first it was the speed at which the lens focuses but there are times when this lens is able to quickly focus. I also turned off the lens stabilizer to see if it made any difference but it didn't.

If it was the camera at fault then there would be more reports from owners of this camera.

I wonder if camera lens have a software update?

Brian

You can find all firmware updates here:

http://av.jpn.support.panasonic.com/support/global/cs/dsc/download/

G7 still has focus hunting (just google "G7 Focus Hunting" for lots of videos and forum links). I don't think it's only the lens. Has to do with the focus algorithms. The 45-150mm might have helped because the zoom range is a lot less and it is possible it also is closer to par focal.

There was also an autofocus hack that helped on the GH5 that perhaps would help here (basically involve setting the shutter speed a bit faster for faster focusing in 4K).

JakeJY wrote:

Brisn5757 wrote:

Brisn5757 wrote:

What I'm trying to find out is if I have a fault on my G7 camera or does this normally happen with the G7 camera.

When video recording the focus will change for a moment and what I'm recording goes out of focus. There doesn't seem a reason why the camera should attempt to refocus after it has correctly focused on a subject. There is nothing that becomes near the camera for the change in focus to happen. It can happen once within a 5 minute video clip and goes out of focus for a few seconds. It's enough ruin an important moment.

The camera is set to AFS/AFF

What I need to know is do owners of the G7 camera also have this problem?

If needed I could upload a video clip example.

Brian

Not happy with the focus problem with my G7 camera I did some tests using 45-150mm lens and found it was not the camera but the 14-140mm lens that was causing the problems.

I was able to create the lens refocusing problem by quickly zooming in or out a short zooming amount using the 14-140mm zoom lens. It looks like the lens starts focusing in the wrong direction and keeps focusing for a near object putting the picture completely out of focus then after a short period it starts to focus for a far object and gets the picture in focus again.

I thought at first it was the speed at which the lens focuses but there are times when this lens is able to quickly focus. I also turned off the lens stabilizer to see if it made any difference but it didn't.

If it was the camera at fault then there would be more reports from owners of this camera.

I wonder if camera lens have a software update?

Brian

You can find all firmware updates here:

http://av.jpn.support.panasonic.com/support/global/cs/dsc/download/

G7 still has focus hunting (just google "G7 Focus Hunting" for lots of videos and forum links). I don't think it's only the lens. Has to do with the focus algorithms. The 45-150mm might have helped because the zoom range is a lot less and it is possible it also is closer to par focal.

There was also an autofocus hack that helped on the GH5 that perhaps would help here (basically involve setting the shutter speed a bit faster for faster focusing in 4K).

Thanks JackJY for the info and the link.

I don't normally record in 4k but might do so later on.

Brian

Brisn5757 wrote:

JakeJY wrote:

Brisn5757 wrote:

Brisn5757 wrote:

What I'm trying to find out is if I have a fault on my G7 camera or does this normally happen with the G7 camera.

When video recording the focus will change for a moment and what I'm recording goes out of focus. There doesn't seem a reason why the camera should attempt to refocus after it has correctly focused on a subject. There is nothing that becomes near the camera for the change in focus to happen. It can happen once within a 5 minute video clip and goes out of focus for a few seconds. It's enough ruin an important moment.

The camera is set to AFS/AFF

What I need to know is do owners of the G7 camera also have this problem?

If needed I could upload a video clip example.

Brian

Not happy with the focus problem with my G7 camera I did some tests using 45-150mm lens and found it was not the camera but the 14-140mm lens that was causing the problems.

I was able to create the lens refocusing problem by quickly zooming in or out a short zooming amount using the 14-140mm zoom lens. It looks like the lens starts focusing in the wrong direction and keeps focusing for a near object putting the picture completely out of focus then after a short period it starts to focus for a far object and gets the picture in focus again.

I thought at first it was the speed at which the lens focuses but there are times when this lens is able to quickly focus. I also turned off the lens stabilizer to see if it made any difference but it didn't.

If it was the camera at fault then there would be more reports from owners of this camera.

I wonder if camera lens have a software update?

Brian

You can find all firmware updates here:

http://av.jpn.support.panasonic.com/support/global/cs/dsc/download/

G7 still has focus hunting (just google "G7 Focus Hunting" for lots of videos and forum links). I don't think it's only the lens. Has to do with the focus algorithms. The 45-150mm might have helped because the zoom range is a lot less and it is possible it also is closer to par focal.

There was also an autofocus hack that helped on the GH5 that perhaps would help here (basically involve setting the shutter speed a bit faster for faster focusing in 4K).

Thanks JackJY for the info and the link.

I don't normally record in 4k but might do so later on.

Brian

The advanced manual might be a good resource too.

I presume you tried setting it to AFS to see if it helps and also tried the different AF modes (like face detect, 49 area, single area, described in page 151). If not, it's worth a try. And I presume you are shooting in creative video mode (mode dial switched to it as per page 126). This is the only mode where all the movie settings are actually fully applied and you can setting your shutter speeds manually.

ftp://ftp.panasonic.com/camera/om/dmc-g7_adv_en_om.pdf

JakeJY wrote:

Brisn5757 wrote:

JakeJY wrote:

Brisn5757 wrote:

Brisn5757 wrote:

What I'm trying to find out is if I have a fault on my G7 camera or does this normally happen with the G7 camera.

When video recording the focus will change for a moment and what I'm recording goes out of focus. There doesn't seem a reason why the camera should attempt to refocus after it has correctly focused on a subject. There is nothing that becomes near the camera for the change in focus to happen. It can happen once within a 5 minute video clip and goes out of focus for a few seconds. It's enough ruin an important moment.

The camera is set to AFS/AFF

What I need to know is do owners of the G7 camera also have this problem?

If needed I could upload a video clip example.

Brian

Not happy with the focus problem with my G7 camera I did some tests using 45-150mm lens and found it was not the camera but the 14-140mm lens that was causing the problems.

I was able to create the lens refocusing problem by quickly zooming in or out a short zooming amount using the 14-140mm zoom lens. It looks like the lens starts focusing in the wrong direction and keeps focusing for a near object putting the picture completely out of focus then after a short period it starts to focus for a far object and gets the picture in focus again.

I thought at first it was the speed at which the lens focuses but there are times when this lens is able to quickly focus. I also turned off the lens stabilizer to see if it made any difference but it didn't.

If it was the camera at fault then there would be more reports from owners of this camera.

I wonder if camera lens have a software update?

Brian

You can find all firmware updates here:

http://av.jpn.support.panasonic.com/support/global/cs/dsc/download/

G7 still has focus hunting (just google "G7 Focus Hunting" for lots of videos and forum links). I don't think it's only the lens. Has to do with the focus algorithms. The 45-150mm might have helped because the zoom range is a lot less and it is possible it also is closer to par focal.

There was also an autofocus hack that helped on the GH5 that perhaps would help here (basically involve setting the shutter speed a bit faster for faster focusing in 4K).

Thanks JackJY for the info and the link.

I don't normally record in 4k but might do so later on.

Brian

The advanced manual might be a good resource too.

I presume you tried setting it to AFS to see if it helps and also tried the different AF modes (like face detect, 49 area, single area, described in page 151). If not, it's worth a try. And I presume you are shooting in creative video mode (mode dial switched to it as per page 126). This is the only mode where all the movie settings are actually fully applied and you can setting your shutter speeds manually.

ftp://ftp.panasonic.com/camera/om/dmc-g7_adv_en_om.pdf

I've had the camera for a year and have mainly used it for taking photos.
My camera setting is in the P Code for most things and focusing at the center spot.
I also press the movie button rather than press the shutter button when recording video as the camera can set itself up for the condition of the scene and I can take snap shots while video recording .
I have not considered other settings but it might be worth while experimenting now that I can cause the camera to go out of focus when I want it to (at least most of the time).

Brian

Brisn5757 wrote:

JakeJY wrote:

The advanced manual might be a good resource too.

I presume you tried setting it to AFS to see if it helps and also tried the different AF modes (like face detect, 49 area, single area, described in page 151). If not, it's worth a try. And I presume you are shooting in creative video mode (mode dial switched to it as per page 126). This is the only mode where all the movie settings are actually fully applied and you can setting your shutter speeds manually.

ftp://ftp.panasonic.com/camera/om/dmc-g7_adv_en_om.pdf

I've had the camera for a year and have mainly used it for taking photos.
My camera setting is in the P Code for most things and focusing at the center spot.
I also press the movie button rather than press the shutter button when recording video as the camera can set itself up for the condition of the scene and I can take snap shots while video recording .
I have not considered other settings but it might be worth while experimenting now that I can cause the camera to go out of focus when I want it to (at least most of the time).

Brian

This is the part that Panasonic cameras can get confusing. When pressing the record button in any other mode on the mode dial, the video recording settings are fully automatic. For example even if you set a ISO, the video will not respect that setting, but rather will be full auto. Only in the Creative Video Mode on the mode dial does it actually follow your settings for aperture, shutter, and ISO. There were other threads where people got confused by this, so this is just something to be aware of.

For peace of mind I put another 14-140mm lens on my camera when in a camera shop, went outside to find out if I had the same focusing problem with the camera and it looks like its a characteristic of the lens.

Someone claims to have solved the problem

https://www.youtube.com/watch?v=rZ6574vvUQU

I have not checked out what he suggests

Brian