View Full Version : How do you read IRE levels in Canon XH A1?


Kareem Dimashkie
February 27th, 2009, 11:38 AM
Hi everyone,

I am shooting on a green screen, and I was advised to set the green screen's IRE level in the camera to 50. How can the XHA1 allow me to see what IRE level the green screen is at?

Thanks,
Kareem Dimashkie

Brian Pratt
February 27th, 2009, 12:38 PM
Can't help you on IRE levels but some good help info here

General Specialist: Greenscreen and Bluescreen Checklist (http://generalspecialist.com/2006/10/greenscreen-and-bluescreen-checklist.asp)

Petri Kaipiainen
February 28th, 2009, 06:18 AM
I do not think you can check the levels on camera, you need vectorscope for that. Or something like DVRack or Canon Console which I use for greenscreen checking (level thin line at 50 IRE means flat even light).

One workaround is to have editor handy: shoot the backgound on tape and capture (or capture straight to HDD if possible), and use the scopes in the editor. Better than nothing.

One method would be to use zebra, set zebra level as low as possible and overexpose a bit, this would show the evennes of the light. Simple calculations could also give you the 50% level: zebra at 75% and one f-stop overexposure should give zebras at 50%.

Hope these ideas help.

Don Palomaki
February 28th, 2009, 08:15 AM
You can approximate IRE metering for a uniformly lit flat field object, such as a green screen in manual exposure mode using the meter scale in the upper left corner.

The triangle in the top center of the scale corresponds to approximately 50 IRE, and the scale divisions are in about 10 IRE steps. If you adjust the exposure so the exposure indicator marker that slides below the scale is in the center under the triangle the brightness is about 50 IRE.