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Jeremy Collins
Filming CRT TV's / Clear Scan Issue (Canon XH-A1)
on Dec 29, 2011 at 9:16:27 pm

Hey All,

I'm having an issue that I can't seem to figure out:

I have a project where I need to film 9 separate old CRT TV's at the same time. I'm using an Canon XH-A1.

I knew I'd have to use the clear scan function to removing the rolling bars, but I've been worried that the different TV's will fall under different clear scan frequencies. So I plugged in 2 of the TV's and decided to play around with it. I was able to remove the first TV's rolling black bars with a frequency of 60.1Hz (the minimum I can go to on my camera), however on the second TV, I couldn't remove them at all. The best I can get is slow rolling bars at 60.1Hz, but they are still pretty dominant.

From what I understand, the clear scan function is more designed to shooting CRT monitors, but I didn't know if anyone had every dealt with something like this, knows a workaround, or if I am just kind of screwed.

Thank you in advance!


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Todd Terry
Re: Filming CRT TV's / Clear Scan Issue (Canon XH-A1)
on Dec 30, 2011 at 1:41:38 am

[Jeremy Collins] "From what I understand, the clear scan function is more designed to shooting CRT monitors"

Well, clearscan modes are for any conditions where you need very precise control over shutter speed to reduce flickering or phasing... such as monitors, fluorescent instruments, or HMIs.

Your problem is interesting...

One question, which your post didn't specify... are these CRTs television monitors, or computer monitors? Your question didn't say which.

If they are television monitors, I can't think of an explanation for why that is happening. In that case, a clearscan shutter speed of 60.1 should wipe out any bars or scanning.

One suggestion would be to power your camera from AC power, not the camera battery. That would make sure that the camera and monitors are all phasing together.

If they are computer monitors, it may be that the refresh rate on some of the monitors is not 60Hz, which is what you would need them to be for the 60.1 shutter speed to work. Try going in to the control panel and double-checking to make sure each monitor is 60Hz (on PCs that would be CONTROL PANEL > DISPLAY > SETTINGS > ADVANCED > MONITOR).

As a last resort, you might try shooting at a lower shutter speed, such as 1/24th or so. If you don't have much action in the frame, that might look ok.

You also didn't tell us what your framerate is. I'm guessing 24p (Canon's 24f), but you didn't say. You might try shooting at other framerates, 30p (30f), or 60i... and (assuming one of those gives you clear results) converting that footage to whatever framerate your project is.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Jeremy Collins
Re: Filming CRT TV's / Clear Scan Issue (Canon XH-A1)
on Dec 30, 2011 at 3:28:55 am

Hi Todd,

Thanks for getting back to me. It actually is a CRT TV, not a computer monitor. I am shooting 24p. I tried AC power, as well as different frame rates, but got the same result.

I tried some other CRT TV's and they all were fine with the 60.1 clearscan. It's this one which is odd. I may need to simply disgard it from this project since I can't think of anything else.

Thanks again!


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Todd Terry
Re: Filming CRT TV's / Clear Scan Issue (Canon XH-A1)
on Dec 30, 2011 at 4:17:56 am

That's weird, Jeremy... can't really come up with an explanation for it.

Sounds like the easiest thing would be to junk that particular monitor and replace it with another, if it is just one out of the nine that is causing problems.

There are other solutions, but they would be more complicated... like gutting the monitor housing and replacing the tube with another screen (it could be an LED), or doing a lot of screen replacement in post. That might require a fair bit of rotoscoping work and motion tracking if your shots have movement.

Good luck!

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Jeremy Collins
Re: Filming CRT TV's / Clear Scan Issue (Canon XH-A1)
on Dec 30, 2011 at 4:26:40 am

Yeah, I think I'm just going to swap it out, seems the most painless. Thanks again for your help Todd!


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