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record LCD screen with 5D
I shot an LCD screen with the Canon 5D a couple weeks ago. I did a few tests and will do some more tests tomorrow. The issue that I am having is that I am seeing an interference pattern/line in the 5D footage that I do not see with my eyes and the client now objects to this for future work. I shot 1920 X 1080P, NTSC.
I minimized the objectionable pattern with a 30 fps frame rate and 1/30th second shutter speed, although the pattern is still there a bit. I realize this is not an ideal 180 degree shutter/frame rate combo. I called Canon USA today and they coincidentally suggested that this is the best rate/shutter combo based on a monitor refresh rate of 60 hz. (I am not yet sure of the monitor refresh rate).
I have a couple of questions for Creative Cow experts. 1.) Is there a 5D frame rate/shutter speed combination that can make this interference pattern go away? 2.) Does the interference pattern have anything to do with the refresh rate of the LCD monitor? If I can change the refresh rate on the LCD monitor, what is my best option? 3.) is this interference pattern due to the CMOS sensor scan behavior? 4.) Are LCD screens generally different to shoot on video than CRT screens or exactly the same? 5.) Is there a “hack” that will “clear scan” or “synchro scan” to sync and remove this pattern? Has anyone else ever had this issue with the 5D and what is your best advice (shoot with a different camera, etc.)
CHEERS LT3
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5 Replies
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Hi Laurent. Why do you want to capture it with a 5D? Are you trying to capture more than just the screen? Or if it is screen only (i.e., screencast), have you tried Camtasia?
Norman Willis
http://www.nazareneisrael.org -
Norman, This series of videos involve talking heads and a product that has an LCD interface screen. I shot the first series of videos with the Canon 5D and my tests were approved by the client. This next series of videos includes close ups of the interface screens and operators hands, etc. If I can’t fix “in camera” with the 5D to the clients satisfaction, then I will have to rent an HD camera with synchro scan to test and fix issue to client’s satisfaction and then rent same camera for the full week shoot coming up. I own the 5D. I have not tried Camtasia. Will Google Camtasia! Thanks, LT3
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You have such limited control over the shutter with a DSLR, this is a limitation of the format, you should use a HD camera. I would also recommend a CCD type sensor, like the HVX or HPX Panasonics.
Also you are not seeing interlace, but every display has a refresh rate and even though it is a progressive DSLR have a rolling shutter so the entire image is not being exposed to the sensor at the same time.
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Thank you, Michael Sacci. I was afraid the issue was inherent to the CMOS rolling shutter on the 5D and/or limited control of DSLR shutter. All the Best, LT3
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Today’s update to this thread—I just tested an HD LCD screen at the client’s headquarters. This screen is a newer model touch screen with different specs and is their current production model user screen. It looks just fine when shot with the Canon 5D. There are a few very minor banding issues when viewing a plain gray screen, but all in all, the client finds the current production screen image shot on the Canon 5D acceptable. Thanks everyone for your input! Norman, this client tells me that they DO use Camtasia frequently. All the Best, -LT3
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