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Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 6:44 pm
by Austin Spinks
I've just shot some test footage today and decided to see how far I could push it in RAW.

I've noticed that certain situations there appears to be a certain amount of flicker, like what you would see with incorrect pairing of frame rate and shutter angle.

Here is a link to what I mean - (uploaded earlier)

You can't really see an issue on vimeo, but if you download the original file (RAW to prores 422HQ conversion) You can clearly see the line flickering within the darker areas. The settings on the camera were 25FPS 180 shutter angle. You can see that there are lamps presents but i'm pretty sure they weren't turned on, so its just daylight.

I've also noticed that I get the same issue with particular bulbs, theres an energy saving bulb in my house which will give strobing no matter what settings are used on the camera, but i've just took that one as being a dodgy bulb.

Any thoughts? Could the problem in the video be caused just by pushing the raw too far?


Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 6:50 pm
by adamroberts
What was your exposure in that shot?

Looks like it might have been under exposed and by pushing it back up in post you are getting flicker from the DNGs being pushed.

What did you process the clip in?

Care to share a DNG?

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 6:58 pm
by Austin Spinks
Hi Adam,

Well I did expose for the sky to then bring back everything else.

Here is the DNG.

https://docs.google.com/file/d/0BwTKbvO ... 9PZ3M/edit

I used after effects CS6 to open the raw footage, using the standard Photoshop type sliders that you get when you open the files up.

I guess you're probably right about the under exposure, looking at the file by itself. I didn't realise this would cause the banding though!

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 7:45 pm
by Felix Steinhardt
Various people have reported this flickering.

What I see from here is that you lifted the shadows really too much. Like ISO 4000 too much.

This would be how I set the contrast.
Blacks are just faintly clipped and highlights are all pulled back

Edit: Uploaded wrong grade. Now it´s the right one

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 7:47 pm
by Austin Spinks
Guess I was maybe trying to push it a little too hard ;) Now I know though!

Cheers guys.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 7:59 pm
by adamroberts
To expose for the sky were you using the in camera zebras?

With the zebras set to 100% you will know when the sensor is clipping. You want to give everything as much exposure as possible without clipping anything that's important. So for example the sun itself might clip but your clouds don't.

John Brawley has a really good description on how he approaches exposure on the camera. He posted his thoughts on the BMCUser forum. Worth searching out and reading the full post (or he might add it here).

I'll have a look at the DNG when I get a moment.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 8:30 pm
by adamroberts
The exposure on that DNG looks fine?

Did you use the Highlight slider in camera RAW? Chatting to Christian Schmeer today about it and he seems to think that might be the cause of flicker in his footage. I'm gonna do some tests over the weekend.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 9:47 pm
by John Brawley
I wonder.....

Those that are using CS6....

If there was a slight difference in frame to frame operations....like noise reduction....

Would that cause a difference ? CS6 isn't designed for motion. I wonder if that's what we're seeing with these kinds of flickering issues.....

I'm on an iPad and can't download the clip so it's a total guess, but it just occurs to me that there's no temporal consideration for the way cs6 processes clips.....be interesting to put it through resolve....

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 9:59 pm
by adamroberts
John that was my thought to. The CameraRAW plugin might be applying adjustments specific to each frame rather than the same adjustment to all frames.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Jan 26, 2013 10:35 pm
by Austin Spinks
Very interesting guys, I'll get the footage into resolve on Monday and see if there are any differences (I also now have a feeling there may be, but you never know) and I did use the highlight slider...

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 3:12 am
by Christian Schmeer
Hi Austin, could you try the same grade (as close as possible) without using the curves or highlights / shadows / darks / blacks adjustments? Just with exposure fixed and your colour adjustments. Try that, export it and see whether the flickering is still there.

I really think the issue comes from the way Camera RAW and Lightroom handle the frames individually, as if they were separate still photographs. To the software, setting the exposure is probably not dependent on what the image contains, whereas the curves adjustments might be done after analysing the highlights and shadows contained within each image / frame. If one or a few frames are analysed differently to the others in the sequence, you'd get a flicker in the moving images that are eventually created from the individual frames. I might be totally wrong about this though...

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 1:31 pm
by Austin Spinks
I've just graded the footage like you said, only changing the colour of the grade. The issue is still present...

I also noticed something today... When I turned my camera on, with the body cap attached... I noticed that I could see the same rolling lines going down the screen. (The camera was set on prores, but I dont think that makes a difference) I'll upload both of these files shortly so you can see what I mean.
The rolling lines aren't visible immediately on my macbooks monitor (At this point I was thinking it was just on the BMCC screen.. but I recorded what I was seeing) and if you up the exposure on the grade you can see exactly what I was seeing on the screen.

Can anyone else see these moving lines while the body cap is still on the camera?

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 2:00 pm
by Austin Spinks
Here is the link to the re-grade of the original footage, without changing any sliders and just the colour temperature.

https://docs.google.com/file/d/0BwTKbvO ... dWVU0/edit


and here is the rolling line issue I mentioned, this is even visible without having to download the original file (Given that I have increased the exposure so you can see it easier)

https://docs.google.com/file/d/0BwTKbvO ... 1ORFE/edit




Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 2:10 pm
by Felix Steinhardt
I remember someone else reporting this rolling lines and they were not always there. Sometimes they were consistant, sometimes they went away after a few seconds. I´m afraid there´s some electric interference going on inside the cam.

When you take Adam Roberts Low Light example and push it 4 stops, you can see those lines, too.
http://www.imagebanana.com/view/jkn18ft7/ISO8001.jpg

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 2:13 pm
by Austin Spinks
Do you think that this problem may only be present in some cameras? Or it's a general problem because of the way the camera is built?

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 9:02 pm
by Christian Schmeer
Austin, I can't access your files. It says "You need permission to access this item."

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 9:13 pm
by Austin Spinks
Sorry about that Christian, forgot to enable public viewing. Have done that now so the files should be visible to you.

I think that the idea of some kind of internal 'interference' would seem to be quite likely. As said, the problem isn't consistent. Some times its there, sometimes its not, sometimes its there but not as bad.

I've already contacted my distributor and will try and contact black magic directly, not really sure how I go about doing that though...

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 10:31 pm
by John Brawley
Austin Spinks wrote:
I also noticed something today... When I turned my camera on, with the body cap attached.... but I recorded what I was seeing) and if you up the exposure on the grade you can see exactly what I was seeing on the screen.



I think another user on another forum reported something similar in this situation....and this is my opinion of what was happening....

When you are lifting black detail BEYOND black you're going to see these kinds of issues. Because of the RAW files and the very "honest" way it works you get everything that the sensor captures, including noise and these kinds of faults below the point where any shadow detail is captured.

It's up to you in the grade to decide where to *clip* these blacks. If you don't, you might be able to eke a bit more dynamic range out of the camera, but it will be with the chance of having issues like this.

It sounds like you're seeing it when you have a shot where black is lifted beyond where you would expect to see detail anyway. You're hitting the DR limit of the camera.

I'm on an iPad and not looking at your shots so I am also guessing from what you're describing.

jb

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 10:39 pm
by Felix Steinhardt
You should take a look at the lens cap file, John. You were involved in developing the camera so you can judge if that´s normal or not. Maybe this is firmware fixable and it´s better when you tell BMD than hundreds of customers that get stuck in "please make sure you connected the power cable" kind of answers from BMD Service.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 10:42 pm
by John Brawley
Yeah it's hard for me to judge that right now. There is definitely sensor traits you're going to see when you stretch the files. I suggest he should contact BMD support to be sure.....

The engineering team do read these forums so you can be sure they'll be looking into it anyway....

jb

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 10:45 pm
by Austin Spinks
Hi John,

I regard this to be an issue with the camera due to the fact that the problem is inconsistent. If it was there all of the time then I would just see this as a quirk of the camera, but the fact it changes by itself, without changing settings / lighting, leaving the camera by itself, suggests to me there is something else going on.

Take a look at the moving horizontal lines on the video I posted when you get the chance, I think you may be able to see my issue. You leave the camera on a while and (After a random amount of time) the problem settles... sometimes. You restart the camera and its right back there again..

Also I noticed you mentioned the issue with RAW.. this problem is consistent across all three format settings on the camera.. so isn't just a RAW issue.

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 10:53 pm
by adamroberts
Austin how did you create the "cap on" clip? Was it shot in RAW or Prores? If Prores what ISO?

It may be, as John described, that you have lifted the blacks and this is what you are seeing the scan lines.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 10:53 pm
by John Brawley
Austin Spinks wrote:
Also I noticed you mentioned the issue with RAW.. this problem is consistent across all three format settings on the camera.. so isn't just a RAW issue.

Austin.



Hi Austin.

As I said I'm just guessing. When I say RAW, it's more the philosophy behind the camera...that it's unadulterated. The ProRes also does't have any noise reduction, or other camera processing that others would expect. It's a straight conversion.

You may also have a faulty camera too of course.

The fact that it changes might also indicate to me it could be cooling related...all sensors will have different noise responses (black shading) depending on how hot they get / are. The camera does have an active cooling system, (like the Alexa) and it could be something going on there....

As I say, I'm just guessing and I'm certainly not an engineer ! The best way to pursue this would be to get in touch with support.

jb

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 11:41 pm
by Austin Spinks
The settings on the camera for the test with the lens cap on were, 800ASA 25FPS Prores.

I've sent BMD support quite a lengthly message detailing the issue (With the potential of a cooling problem.. or something along those lines) so hopefully they will get back to me promptly. I'll report back here when i receive a response.

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Jan 27, 2013 11:52 pm
by John Brawley
Austin Spinks wrote:The settings on the camera for the test with the lens cap on were, 800ASA 25FPS Prores.

I've sent BMD support quite a lengthly message detailing the issue (With the potential of a cooling problem.. or something along those lines) so hopefully they will get back to me promptly. I'll report back here when i receive a response.

Austin.


I'm only guessing. I wouldn't say for sure it's a cooling problem ! Best you let the engineers respond to this....

jb

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Mon Jan 28, 2013 12:07 am
by Felix Steinhardt
Austin Spinks wrote: You leave the camera on a while and (After a random amount of time) the problem settles... sometimes. You restart the camera and its right back there again..
Austin.


That really sounds and looks like a electromagnetic shielding problem. Maybe it´s the cooling fan changing RPM. Should be a piece of cake to shield the emitting component with some aluminium foil when it´s identified.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Mon Jan 28, 2013 12:08 am
by John Brawley
Felix Steinhardt wrote:
Austin Spinks wrote: You leave the camera on a while and (After a random amount of time) the problem settles... sometimes. You restart the camera and its right back there again..
Austin.


That really sounds and looks like a electromagnetic shielding problem. Maybe it´s the cooling fan changing RPM. Should be a piece of cake to shield the emmiting component with some aluminium foil when it´s identified.


The cooling fan doesn't change RPM. It's constant.

I don't know that it's useful to speculate more than we have on the issue without hearing from BMD.....

jb

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Mon Jan 28, 2013 8:41 am
by adamroberts
If you watch Alx's trailed you see the same rolling noise patten in the dark shot with the glasses (0:02) and to last shot with the red LEDs (1:11). Granted it's heavily compressed but they are the only 2 scenes that exhibit the issue.

viewtopic.php?f=2&t=4524

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Jan 29, 2013 2:03 pm
by Austin Spinks
Hi guys,

I've been in discussion with BMD and they have acknowledged the issue as a real problem and am now in the process of sending the camera into them for tests!


Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Jan 29, 2013 2:12 pm
by Christian Schmeer
Austin Spinks wrote:Hi guys,

I've been in discussion with BMD and they have acknowledged the issue as a real problem and am now in the process of sending the camera into them for tests!


Austin.


I have had a look at the video file you posted now. I'll have a look if the issue is present on my camera as well. Maybe I was totally wrong about it being Lightroom related on my camera as well :oops:

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Jan 29, 2013 2:27 pm
by Austin Spinks
Hi Christian,

Yeah if you could let me know if the problem can be seen on yours that would be interesting. Basically if you turn the camera on with the body cap attached, I can visibly see the horizontal lines bouncing up and down the screen, very interference like.

Here is another video that I uploaded to show BMD the problem. (Download the original file)

https://docs.google.com/file/d/0BwTKbvO ... lFbGs/edit


Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Jan 29, 2013 2:51 pm
by adamroberts
I just ran a similar test on my camera.

With the cap on.
Camera set to record ProRes.
Set to 800ISO.
Display set to max brightness.

Tried both Video and Film view and not seeing any interference on the LCD.

Recorded ProRes Film and ProRes Video with the above settings. Open in FCPX and the both clips are clean black.

Looking at the RGB parade:
Film comes out just above 0 (about 5%)
Video come out just below 0 (about -1%)

If I then boost the exposure in FCPX by 20% I get some interference in the (now grey) image. But I'd expect that as you are boosting the signal noise.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Jan 29, 2013 3:06 pm
by Christian Schmeer
Austin, do you get the interference/lines in ProRes as well? I have just shot a ProRes file with my lens cap on and upped the shadows in FCPX. There are no interference lines as shown in your video, but the 50/50 split shows (as shown in this thread: viewtopic.php?f=2&t=4269)

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Jan 29, 2013 3:32 pm
by Felix Steinhardt
mmh, another idea. Can it be caused be external EM fields like WiFi, Cell Phones etc.?
I once had a similar problem with my TV reception years ago and it was my DECT phone.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Jan 29, 2013 4:33 pm
by Austin Spinks
The issue happens whenever and wherever on the camera. It occurs on all settings and all modes!

If your camera has this issue you would certainly know about it, it does not require any post manipulation to try and pull the problem out, its blatantly there when you turn the camera on.

I believe that I just have a defective model, its good to know that others don't have this problem though, hopefully my replacement camera will be perfectly sound.

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Jan 29, 2013 5:29 pm
by A-styles
Maybe you should gel the light. But I don't know what type of bulb you used or what the color balance is. And did you have the focus assist on if so that could be the camera trying to help you focus. I'm just trying to help based on what you wrote.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Jan 29, 2013 5:34 pm
by adamroberts
A-styles wrote:Maybe you should gel the light. But I don't know what type of bulb you used or what the color balance is. And did you have the focus assist on if so that could be the camera trying to help you focus. I'm just trying to help based on what you wrote.



Um... you'll notice it you read the thread that it happend with the body cap on the camera. So no light is getting in. So no gel or colour balance setting will make any difference....

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Thu Jan 31, 2013 7:05 pm
by Austin Spinks
Update: BMD received my returned camera today. Was put through testing and was shown to be faulty. New one should be on it's way soon! Hooray!

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Thu Jan 31, 2013 7:43 pm
by Felix Steinhardt
Good to hear!
I´m relieved because if someone gets a broken camera, it´s me, always been the same :mrgreen:

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Thu Jan 31, 2013 8:01 pm
by Austin Spinks
Well if you / anyone has this issue with the camera, BMD will acknowledge the problem and get it sorted ASAP!

Very good customer support.

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Thu Jan 31, 2013 8:23 pm
by Christian Schmeer
I'm glad to hear BMD took care of the problem so quickly. How did you send it to them? Did you have to send it to Australia or a local BMD representative?

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Thu Jan 31, 2013 8:48 pm
by Austin Spinks
I think there are a number of difference scenarios that can happen in the UK. I gather anyway. The main distributor for the UK is Holden. They contacted me originally alongside BMD and I assume it is either Holden or BMD themselves who will take up the problem. If its a problem like mine, where BMD want to test the product then BMD will take it on and deal with you directly. I guess if the product is clearly not acceptable then Holden will take on a replacement for you. (Or something alone those lines)

For the UK BMD have a support team down in Cheshire, they requested that I send the camera back using their UPS account, so the courier didn't cost me anything and got there next day!

Very happy with the service, just waiting to get the new camera now (Which I was told would be 2 days after they check the fault on the camera)

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Wed Feb 06, 2013 10:40 pm
by Austin Spinks
So, the DAY after I sent my camera into BMD support, I got a brand new one! (How they turned round a brand new camera for me in a single day, I don't know. But regardless its very impressive).

Luckily this one is fine, hooray!

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Wed Feb 06, 2013 11:16 pm
by adamroberts
Good to know.

I think this pretty much shows that even with all the waiting and complaining on this forum, Blackmagic is company that looks after it's customers.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Wed Feb 06, 2013 11:17 pm
by Austin Spinks
For sure! I don't have any complaints about their service at all.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Thu Apr 11, 2013 5:31 am
by Dustin Svehlak
Wanted to bump this but it looks as though I've having the same issue. Heres a video on my Dropbox showing the issue (you'll have to download to see as DB's compression is horrific)-

https://www.dropbox.com/s/0e0ewutx1vesu ... 01080p.mov

This was disappointing as I just took delivery of the camera today. It worked fine for about 10 shots then this happened. Seemed to coincide with loud music from my car... All the audio was distorted for any bass that was hitting, it was weird (just on camera mic).

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sat Apr 13, 2013 9:37 pm
by Dustin Svehlak
Just wanted to bump this again, I've been in touch with BM support and they have a couple clips and DNGs demonstrating the issue. They are scheduled to get back to me Monday so I'll report back what I find.

I'm starting to think that it may have been the bass off my car stereo, or at least something sound related. The audio was very distorted when there were any bass hits.

Has anyone else had any issues with bass causing really bad distortion with the built-in mic? It wasn't even peaking on the recording, I'm pretty stumped.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Sun Apr 14, 2013 9:44 pm
by Austin Spinks
Very difficult to see from the video - Kinda looks like big macro blocking.. Probably just the compression uploading online though.

Austin.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Tue Apr 16, 2013 1:46 pm
by Dustin Svehlak
Austin Spinks wrote:Very difficult to see from the video - Kinda looks like big macro blocking.. Probably just the compression uploading online though.

Austin.


Yeah Dropbox's compression will not show the issue. You'll have to download the file, but I'm about to remove it to make space in my cloud.

That said, Adorama graciously offered to exchange my camera, even covering shipping, so it's back to them at the moment. I'll report back if anything else goes wrong but I consider this resolved.

Also, Blackmagic support was very helpful but wanted to perform more troubleshooting. They recommended that if Adorama was offering an exchange I go ahead and make that move, so I did.

Re: Flicker/ Light Strobing Camera Issue

PostPosted: Fri Apr 19, 2013 12:36 am
by sicovanderplas
I have the same problem with strobing and flicker

Did they came to a conclussion at Adorama?