Weird problems with image at DVinfo.net

Simon Frances · January 26th, 2008, 06:49 PM

I shot some footage a couple of days ago just as a test and have noticed the following problems:

The obvious light flickering, which if you look closely is across the whole picture, although not as noticeable as in the original footage. The cars seem to have a strobing effect and the image is rapidly going in and out of focus (more noticeable when looking at the building on the right in the long shot.

I also note the motion blur on the cars don’t seem right.

It was shot in PAL, 35 mbps (VBR), 25p, 1920 x 1080. The shutter was set to 1/50, can’t remember what the iris was set too but I think around f/4 but could be less, gain was set to -3 and manual white balance. Not sure whether auto or manual focus.

Link to compressed footage.
(FYI, It’s download: 2.2.mov)

Link to original footage.

Any help would be greatly appreciated.

Regards,

Simon

Paul Joy · January 26th, 2008, 07:11 PM

The compressed footage looks very strange Simon, Does the original show the pulsating effect on the tree's etc too?

I looks like a compression artifact to me, but I really don't know how the camera could be made to do something like that. My guess would be that you have some kind of fault there if the uncompressed footage looks the same.

Could you post a shorter clip of the original footage - 525Mb is a lot to dl.

Steven Thomas · January 26th, 2008, 07:34 PM

Very strange!
It can't be anything like auto exposure since it does not react that fast (as it should not) and it appears that only the horizon and above flickered. I have never seen this with my EX1.

Have you seen this on any other footage you shot?
I wonder if the auto knee was being weird? This may explain it. Were you using a standard gamma? With cine gammas this is fixed.

Uwe Boettcher · January 27th, 2008, 01:11 AM

Hello!

I think, it is the auto focus.
If you look at around 1 minute you can see it switching between the cars and the trees.

Your car has a nice sound!!!

Kind regards,
Uwe

Simon Frances · January 27th, 2008, 07:56 AM

Hi Guys,

[Paul]
The uncompressed footage (original) exhibits the same problems. The original footage is the BPAV folder so I don't think I can make it shorter, or can I?

[Steven]
The settings changed in picture profile were: High SAT, Detail Off, CINE 4, Black -3, Black Gamma -2. All the rest were set to default, although Knee was grayed out.

Manual Focus Assist and Steady Shot were both set to OFF.

As for some of the footage I’ve shot, I’m not overly impressed with the quality. I don’t know if this is down to this specific camera though.

I had a check through some other test footage and noticed the same but with artificial lighting, please click here.

[Uwe]
I was charging up the battery after not using it for the last four months. :)

Regards,

Simon

Uwe Boettcher · January 27th, 2008, 08:14 AM

Hello Simon!

Did you do a manual focus test?

At the end of your clip i think, the focus is on the branches of the tree. So the building ist not sharp!

Uwe

Simon Frances · January 27th, 2008, 08:36 AM

Hi Uwe,

I've tried both manual and auto, however I would like to be able to work in auto focus should I want to. I used to have a Canon A1 prior to this and got better results both with the auto focus and the picture quality. Then again it could just be my camera.

Uwe Boettcher · January 27th, 2008, 09:17 AM

Hi Simon!

The auto focus is really not as good, as it should be. No comparison to the Z1.

I think you are right and the EX1 is flawed!

Kind regards,
Uwe

Simon Frances · January 28th, 2008, 05:26 AM

Please also note, the links in the other posts are no longer active, as I've been having problems with my hosting. I've now changed my hosting company and here are the new links: Test clip 1. and the compressed clip, Test clip 2.

Thanks,

Simon

Paul Curtis · January 28th, 2008, 06:28 AM

There's an insane amount of sharpening and ringing around the edges of everything this could be 'eating' into the branches and creating a pulsing effect - in other words the effect is a post effect, either in camera electronics or in your workflow.

Does all your footage look like this? Can you shoot some more and compare?

paul

Simon Frances · January 29th, 2008, 05:19 AM

Quote:

Originally Posted by Paul Curtis

There's an insane amount of sharpening and ringing around the edges of everything this could be 'eating' into the branches and creating a pulsing effect - in other words the effect is a post effect, either in camera electronics or in your workflow.

Hi Paul,

I've been so focused on the light flickering, that I didn't realize the sharpening. I do know it’s not a post issue though, as it’s the same on the original footage.

Quote:

Originally Posted by Paul Curtis

Does all your footage look like this? Can you shoot some more and compare?

I’ve only noticed this effect on occasions; I THINK it seems to be brought on when there is some kind of prominent light source, be it natural or artificial, as per the footage.

Can anyone else see whether their camera is exhibiting these issues, under similar conditions or otherwise?

It would be interesting to also include using auto focus.

Thanks in advance,

Simon

Sean Donnelly · January 29th, 2008, 09:07 PM

I recently shot with the camera in similar conditions, and didn't noticed anything like this. You mentioned the knee settings were grayed out, is it possible you were on auto-knee? The rest of the image seems to remain stable, however the sky is flickering. My guess is the subject matter was "fooling" the auto-knee much like an autofocus system can fluctuate in very low contrast situations, causing it to jump between extremes. Just a thought, but it looks to me like at the high point of the flickering is that the sky is blooming around the branches.

January 26th, 2008, 06:49 PM	#1
Simon Frances Regular Crew Join Date: Aug 2007 Location: London, UK Posts: 58	Weird problems with image I shot some footage a couple of days ago just as a test and have noticed the following problems: The obvious light flickering, which if you look closely is across the whole picture, although not as noticeable as in the original footage. The cars seem to have a strobing effect and the image is rapidly going in and out of focus (more noticeable when looking at the building on the right in the long shot. I also note the motion blur on the cars don’t seem right. It was shot in PAL, 35 mbps (VBR), 25p, 1920 x 1080. The shutter was set to 1/50, can’t remember what the iris was set too but I think around f/4 but could be less, gain was set to -3 and manual white balance. Not sure whether auto or manual focus. Link to compressed footage. (FYI, It’s download: 2.2.mov) Link to original footage. Any help would be greatly appreciated. Regards, Simon

January 26th, 2008, 07:11 PM	#2
Paul Joy Major Player Join Date: Mar 2007 Location: Norfolk, UK Posts: 627	The compressed footage looks very strange Simon, Does the original show the pulsating effect on the tree's etc too? I looks like a compression artifact to me, but I really don't know how the camera could be made to do something like that. My guess would be that you have some kind of fault there if the uncompressed footage looks the same. Could you post a shorter clip of the original footage - 525Mb is a lot to dl. __________________ Blog: www.pauljoy.com Company: www.videotrader.co.uk

January 27th, 2008, 07:56 AM	#5
Simon Frances Regular Crew Join Date: Aug 2007 Location: London, UK Posts: 58	Hi Guys, [Paul] The uncompressed footage (original) exhibits the same problems. The original footage is the BPAV folder so I don't think I can make it shorter, or can I? [Steven] The settings changed in picture profile were: High SAT, Detail Off, CINE 4, Black -3, Black Gamma -2. All the rest were set to default, although Knee was grayed out. Manual Focus Assist and Steady Shot were both set to OFF. As for some of the footage I’ve shot, I’m not overly impressed with the quality. I don’t know if this is down to this specific camera though. I had a check through some other test footage and noticed the same but with artificial lighting, please click here. [Uwe] I was charging up the battery after not using it for the last four months. :) Regards, Simon Last edited by Simon Frances; January 28th, 2008 at 05:25 AM.

January 28th, 2008, 05:26 AM	#9
Simon Frances Regular Crew Join Date: Aug 2007 Location: London, UK Posts: 58	Please also note, the links in the other posts are no longer active, as I've been having problems with my hosting. I've now changed my hosting company and here are the new links: Test clip 1. and the compressed clip, Test clip 2. Thanks, Simon Last edited by Simon Frances; January 29th, 2008 at 05:11 AM.

January 26th, 2008, 07:34 PM	#3
Steven Thomas Trustee Join Date: Sep 2005 Location: Gilbert, AZ Posts: 1,896	Very strange! It can't be anything like auto exposure since it does not react that fast (as it should not) and it appears that only the horizon and above flickered. I have never seen this with my EX1. Have you seen this on any other footage you shot? I wonder if the auto knee was being weird? This may explain it. Were you using a standard gamma? With cine gammas this is fixed.

January 27th, 2008, 01:11 AM	#4
Uwe Boettcher New Boot Join Date: Jan 2008 Location: Germany Posts: 21	Hello! I think, it is the auto focus. If you look at around 1 minute you can see it switching between the cars and the trees. Your car has a nice sound!!! Kind regards, Uwe

January 27th, 2008, 08:14 AM	#6
Uwe Boettcher New Boot Join Date: Jan 2008 Location: Germany Posts: 21	Hello Simon! Did you do a manual focus test? At the end of your clip i think, the focus is on the branches of the tree. So the building ist not sharp! Uwe

January 27th, 2008, 08:36 AM	#7
Simon Frances Regular Crew Join Date: Aug 2007 Location: London, UK Posts: 58	Hi Uwe, I've tried both manual and auto, however I would like to be able to work in auto focus should I want to. I used to have a Canon A1 prior to this and got better results both with the auto focus and the picture quality. Then again it could just be my camera.

January 27th, 2008, 09:17 AM	#8
Uwe Boettcher New Boot Join Date: Jan 2008 Location: Germany Posts: 21	Hi Simon! The auto focus is really not as good, as it should be. No comparison to the Z1. I think you are right and the EX1 is flawed! Kind regards, Uwe

January 28th, 2008, 06:28 AM	#10
Paul Curtis Major Player Join Date: Mar 2005 Location: canterbury Posts: 411	There's an insane amount of sharpening and ringing around the edges of everything this could be 'eating' into the branches and creating a pulsing effect - in other words the effect is a post effect, either in camera electronics or in your workflow. Does all your footage look like this? Can you shoot some more and compare? paul

January 29th, 2008, 09:07 PM	#12
Sean Donnelly Regular Crew Join Date: Jan 2008 Location: New York, NY Posts: 188	I recently shot with the camera in similar conditions, and didn't noticed anything like this. You mentioned the knee settings were grayed out, is it possible you were on auto-knee? The rest of the image seems to remain stable, however the sky is flickering. My guess is the subject matter was "fooling" the auto-knee much like an autofocus system can fluctuate in very low contrast situations, causing it to jump between extremes. Just a thought, but it looks to me like at the high point of the flickering is that the sky is blooming around the branches.