filming computer monitors

[ben jones]

Hi every one. Im a student cinematographer about to embark on my graduation film. We are shooting in an office with a mixture of CRT and TFT monitors. Im shooting super 16mm (7229) and the camera is an sr2. Will I end up with lines on the screens due to frequency differences? If so, How can I over come this as cheaply as possible?

 

Also, I want to shoot using as much available light as possible (tight budget!) so im going to incorporate a lot of practicals. I also wish to utilise the existing office floros. I have done tests using the stills cassettes that Kodak offer, but the labs managed to missplace them. Im shooting in a week and am slightly worried about what colour they will read. Can anyone suggest a suitable method of correcting conventional floros and if not, how easy is it to correct in post?

 

Cheers, Ben (Surrey institute of art and design - England)

[Robert Hughes]

Sounds like a flicker fest. LED displays don't flicker as obviously as CRT's , so use them in your shots exclusively. Fluorescent lights flicker at 120hz; if your camera can reliably run at 24hz you should be OK.

 

Fluorescent filtration filters:

 

http://www.geocities.com/thombell/tung.html

[Brent J. Craig]

As Robert mentioned, LCD screens show no perceptible flicker on film. I believe one of the reasons LCD's were adopted so quickly in the real world is because people saw them on so many TV shows and movies. Of course the film crews used them because they were easy to shoot, but the public just thought they looked cool in the movies.

 

I have noticed that the cold-cathode backlights in some (very few) LCD's flicker at the same frequency as fluorescents. If you stick to HMI safe speeds you should be fine in all cases.

 

CRT monitors are another story. Your camera speed needs to be exactly half of their horizontal scan frequency. If the montior is at 75.000Hz, you need to shoot it at 37.500 Fps, and hold down the phase button until the roll bar moves off screen.

 

If you have control over the computers with CRTs, you may be able to make them scan at 60Hz or (rarely) at 48Hz. At 60Hz you would shoot at 30fps, 48Hz at 24fps.

 

How do you determine the scan frequency of the CRT?

1- Many monitors will display the frequency at which they are operating when you go into their setup menus.

 

2 - Windows machines let you set the scan frequency by following these steps:

-right click on the desktop

-select properties

-select the settings tab

-click advanced

-select the monitor tab

-there should be an option there called "screen refresh rate", choose a new rate and click OK. (Note that they say choosing a rate your monitor can't handle can fry the monitor - who knows if it's true?)

 

Something else to watch out for: With more than one CRT, they will all be in different phases. Removing the roll bar from one will probably show the rollbar on another.

 

The only way to do a room full of CRTs is to have a 24fps video tech come in and sync all the machines to the same source. That's expensive.

 

Also note that with careful planning you can add orange to the color of the images you show on the screens to make them look right on Tungsten film, since monitors are daylight.

 

Since fixing things in post has become so easy, more than half the time we shoot computers now the screens are either off or have greenscreen fabric taped over them. That may be an option in your case.

 

Good luck with your project.

[ben jones]

Hi Craig.

 

Thanks for your advice on the computer monitor problem! If our producer pulls his socks up, I think I may be able to get a fleet of TFT monitors which seems like the best solution. I am not entirely sure if an Arri SR2 has a phase button. I have only used an older sr before, and an AATON XTR production camera.

 

Regards, Ben (not as worried as before) Jones

[Phil Rhodes]

Hi,

 

> LED displays don't flicker as obviously as CRT's

 

> As Robert mentioned, LCD screens show no perceptible flicker on film

 

Careful - that's actually not what Robert said, even if that's what he meant to say. LED video displays, such as the types you might see strapped to a hotel sign in Las Vegas or at an open-air music concert, very definitely flicker on video and we can safely assume that there would be issues with film too.

 

I think you're actually talking about LCD displays, which are a much safer bet (although they can appear to shimmer slightly) - but mixing terminology is dangerous!

 

Phil

[Brent J. Craig]

If our producer pulls his socks up, I think I may be able to get a fleet of TFT monitors which seems like the best solution

 

I will help you translate this into Producer speak: "renting TFT monitors = less $$$ than the cost of a reshoot" :-)

 

 

I am not entirely sure if an Arri SR2 has a phase button.

<{POST_SNAPBACK}>

 

They do.

[Paul Bruening]

Hello friendly people,

 

What about using an LCD to record digital images back to cine film. I understand that an intervalometer will have to be used since exposure times vs scan lines are a factor. Mostly, how does it look? Viewsonic makes a 4K plus LCD monitor even though it is pricey. This way, I could do the anamorphic squeeze digitally, then send the stock to the lab to have the sound laid in and prints made. The issue remains, How does the image look. Will those little grid lines on the LCD screen show up?

 

Thanks,

Paul Bruening

Edited March 27, 2005 by Paul Bruening

[Phil Rhodes]

Hi,

 

> Will those little grid lines on the LCD screen show up?

 

Not if you throw it slightly out of focus.

 

The issue you will have is with contrast range. The very best current LCDs are only 800:1, which will result in a pretty flat-looking film print. I would also fear problems with hotspotting, as you are only at right-angles to the exact centre of the screen.

 

Definitely look into anything with Sony's "X-black" logo on it, which denotes the use of a modified LCD technology which offers much better blacks.

 

Phil

[John Mastrogiacomo]

Hi,

 

LED video displays, such as the types you might see strapped to a hotel sign in Las Vegas or at an open-air music concert, very definitely flicker on video and we can safely assume that there would be issues with film too.

<{POST_SNAPBACK}>

[John Mastrogiacomo]

Hi,

 

LED video displays, such as the types you might see strapped to a hotel sign in Las Vegas or at an open-air music concert, very definitely flicker on video and we can safely assume that there would be issues with film too.

<{POST_SNAPBACK}>

 

Specifically, what signs in Las Vegas are you talking about? I have never had any problems videotaping any marquee signs in Las Vegas and I have videotaped just about all of them. I haven't tried film yet, but will in the next month or so.:(

[Phil Rhodes]

Hi,

 

Then you've been very lucky - I've shot lots of LED screens at open air music concerts and they all flickered like hell.

 

Definitely something to watch out for.

 

Phil

[Owen Cant]

Hello All,

Appreciate this is a very old thread but it is very much in the vain of a test I am carrying out next week.

I will be testing a technique whereby I shoot an LCD monitor with a 16mm celluloid film camera, which is screening footage that I shot digitally. The desired effect being that the resulting 16mm footage, has everything I shot digitally, but with the look and grain of it having been shot on film.

To be specific on the kit:

-I will use a grading suite monitor, an Eizo ColorEdge CG3146

-I will be using either an SR3 or a 416 camera

-I will use an Arri Ultra 16 prime lens

-Provided I can get hold of the stocks I will test 50D 200T and 500T (looking at the different grain)

I will display the film i shot digitally in Log on the monitor, as I will be getting a log scan back from the lab, so it will be a Log to Log process in theory. 

I have done provisional tests already. And I got decent results in terms of grain but there was a moire pattern/or sync artefact in shadow and highlight parts of the image.

I have uploaded the tests here:

https://vimeo.com/manage/videos/878091516

I find it most noticeable at the start in the shadow on the left, and then towards the end of the clip in the sky highlight on the left.

In my next tests I hope to eliminate the wave pattern. I have been speaking to a number of technicians about how this might be at all possible. The recurring answer is that its not possible to sync a 16mm camera with such a modern monitor, however I wondered if there is another workaround?

Another option that has been suggested to me is to use an old CRT monitor, where it was possible to sync a 16mm camera via a speed/sync box? My issue with that though is that the image will be much lower quality than being displayed via the Eizo monitor.

Also, before it is suggested- I have looked into Digital-Film-Digital services as offered by Cinelab in London, but unfortunately that is well out of our budget. Also I am curious to explore if this DIY method will work just for the sake of exploring.

Look forward to hearing any thoughts/insights 

[David Mullen ASC]

I didn't see moire in your test but if it's there, it's not on the film -- it's just because the pattern in the monitor seen on film is interacting with the pattern of the scanner.  I don't think it's a sync issue. Try scanning at a different resolution or use a different scanner? I certainly wouldn't use a CRT monitor but maybe a higher resolution monitor might help.

 

[Owen Cant]

Hi David,

Thanks for your quick reply. It is a subtle pattern but I think the main reason it may have been hard to view, 

especially after being compressed for web is that it was in Log. I have just applied a quick Arri 709 LUT

and added a lot of contrast to make the effect more visible.

It should be quite noticeable now, particularly around 00:30-00:39

https://vimeo.com/manage/videos/878227566

Re scanner- thanks for that tip. I will speak to Kodak/Digital orchard and see what they can do on their side.

This was scanned in 1080, so I might ask for a 2K and a 4K scan to compare in my tests.

I am also wondering if it is anything to do with the framerate they (digital orchard) are scanning at? I'm thinking I should try and match the speed at which the monitor I am shooting at with the speed the scanner will be scanning at in this case?

Thanks for your help much appreciated!

[David Mullen ASC]

The wavy pulse does seem more of a refresh rate issue than moire, unfortunately you'd need to shoot tests at different shutter speeds, otherwise try finding a monitor with a higher refresh rate.

Why not just laser record your digital files to film? Is it because you need 16mm grain? You could try reducing the image to a 16mm area of a 35mm frame then, but of course, I don't know what your end goal is -- a 16mm print to show people? Or are you doing a D.I. with your 16mm project?

[Owen Cant]

Ok sure, I will be doing more tests next week and will try all the shutter speeds available on the sr3.

I will also try shooting with a few other alternative monitors with higher refresh rates and compare.

The reason we aren't laser recording the digital files to film is that its way out of our very limited film school budget- that would of course be the ideal scenario, but thats a good tip regarding reducing the image to a 16mm area of a 35mm frame.

The end goal is to give the finished project 16mm grain, that is more natural looking than any 'digital grain' one could apply in post, or the other technique of overlaying a scan of 16mm stock- both of which don't really look like 16mm to me. 

Thanks for your help- its helped me figure out what to test next.

I'll get back on here with the results,

Cheers

[Jacob Mitchell]

On 10/26/2023 at 5:11 PM, Owen Cant said:

Ok sure, I will be doing more tests next week and will try all the shutter speeds available on the sr3.

I will also try shooting with a few other alternative monitors with higher refresh rates and compare.

The reason we aren't laser recording the digital files to film is that its way out of our very limited film school budget- that would of course be the ideal scenario, but thats a good tip regarding reducing the image to a 16mm area of a 35mm frame.

The end goal is to give the finished project 16mm grain, that is more natural looking than any 'digital grain' one could apply in post, or the other technique of overlaying a scan of 16mm stock- both of which don't really look like 16mm to me. 

Thanks for your help- its helped me figure out what to test next.

I'll get back on here with the results,

Cheers

really love how this looks, let us know if you figure out a solution!