Setting a Sekonic lightmeter for the Canon XL-H1

David W. Jones · January 11th, 2007, 04:25 PM

Well Call me old fashion, but I still enjoy being able to reach for a light meter. Especially when lighting a scene before a camera and monitor ever gets near the set.

Here is a down and dirty way to spec the meter to your camera....

The first thing you need to do when using a light meter with a video camera
is calibrate the meter's ISO number to match the the camera you are using.
This can be done by flat lighting an 18 percent gray card, and then shoot the card with your camera.
Look at what the camera shows for an F-stop, for example F5.6 shooting at 1/60th of a second.
Set the light meter for the same frame reading that you are shooting with your camera,
and then take a reading with the meter.
Change the ISO number until the F-stop showing on the light meter matches the F-stop of the camera.
This will give you the ISO number for that video camera, for example ISO 320,
and will allow you to calibrate the the metering system of the camera and the light meter together.

This should get you into the ballpark.

Floris van Eck · January 12th, 2007, 05:55 PM

Thanks for all the feedback. The method described by David W. Jones sounds like a good starting point. I do have a powerbook 12" with Final Cut Pro so I might be able to use the waveform monitor in there as well.

But then I first need to study the subject. I have no idea how it works.

Floris van Eck · January 13th, 2007, 03:55 PM

I did some testing today with a gray card and I found the following numbers:

-3db is the equilivant of ISO 200
0db is the equilivant of ISO 320
+3db is the equilivant of ISO 400
+6dbis the equilivant of ISO 800
+12db is the equilivant of ISO 1250
+18db is the equilivant of ISO 2500+

I tested them with the default camera settings and a shutter speed of 1/50 with the mode select set to HD (50i). I also tested the Panalook custom preset and got the same results at -3db and 0db. I am sure there will be custom presets that do impact the results but I have not tested all of them yet. I am going to do more extensive testing later on. The results seem right as I heard before that the Canon XL-H1 had a ISO rating of 320.

My only question is what is the difference between -3db and 0db in terms of image quality? With -3db, the camera should rate ISO 200. So is there a penalty I pay in terms of image quality? Otherwise, I will use the -3db setting whenever possible and only go up when there is not enough light.

At least I have a good starting point now.

A. J. deLange · January 16th, 2007, 10:26 AM

Interesting! Thanks for doing that work.

The only difference you should see between -3 dB and 0 dB gain settings is a bit more noise at 0. You'll have to decide for yourself whether you want the speed and can live with the noise or can't tolerate the noise and will sacrifice the speed. In well lit situations it should make very little difference which setting is used. In natural light situations look for the noise in shadow areas as that is where it will be most prevalent though in some scenes (indoor at night w/o supplemental lighting) the whole frame may be "crawling" with noise.

Floris van Eck · January 16th, 2007, 11:10 AM

The strange thing is: why would they call it -3db? As I see it, -3db should have been 0db and +18db should have been +36. The minus gain number makes no sense to me. So I suspected that 0db is the lowest setting and -3db does add some trickery to go even lower. Now you have -3db which is the lowest factor... then you have the A (Auto Gain) and then 0db. I just think they could and should have done this in a different way.

I am currently shooting theatre. The play is called "Mistero Buffo" and only has white lighting. So everything is black or white to say so. I did some tests and you really see the increased noise in higher gain settings.

Like you said, the black areas are the worst in terms of grain.

Shawn Alyasiri · January 16th, 2007, 01:06 PM

"this one goes to 11..." :)

A. J. deLange · January 16th, 2007, 02:48 PM

Gain is a relative thing i.e. it must always be specified relative to some reference point in the system. As we are not being told what the referernce point is the absolute gain is meaningless. It is probable that the labels represents the gain of an amplifier some where in the middle of the chain and that the numbers are the actual gain of this amplifier (i.e. the reference point is it's input). -3dB gain means that if you put 141 millivolts in you get 100 millivolts out (that's right - it doesn't amplify, it attenuates). 0 dB would mean 141 mV in gives 141 mV out, +3 dB would mean 200 mV out for 141 mV in etc.

January 11th, 2007, 04:25 PM	#16
David W. Jones Trustee Join Date: Dec 2006 Location: Little Rock Posts: 1,383	Well Call me old fashion, but I still enjoy being able to reach for a light meter. Especially when lighting a scene before a camera and monitor ever gets near the set. Here is a down and dirty way to spec the meter to your camera.... The first thing you need to do when using a light meter with a video camera is calibrate the meter's ISO number to match the the camera you are using. This can be done by flat lighting an 18 percent gray card, and then shoot the card with your camera. Look at what the camera shows for an F-stop, for example F5.6 shooting at 1/60th of a second. Set the light meter for the same frame reading that you are shooting with your camera, and then take a reading with the meter. Change the ISO number until the F-stop showing on the light meter matches the F-stop of the camera. This will give you the ISO number for that video camera, for example ISO 320, and will allow you to calibrate the the metering system of the camera and the light meter together. This should get you into the ballpark.

January 12th, 2007, 05:55 PM	#17
Floris van Eck Major Player Join Date: Jan 2006 Location: The Netherlands Posts: 993	Thanks for all the feedback. The method described by David W. Jones sounds like a good starting point. I do have a powerbook 12" with Final Cut Pro so I might be able to use the waveform monitor in there as well. But then I first need to study the subject. I have no idea how it works.

January 13th, 2007, 03:55 PM	#18
Floris van Eck Major Player Join Date: Jan 2006 Location: The Netherlands Posts: 993	I did some testing today with a gray card and I found the following numbers: -3db is the equilivant of ISO 200 0db is the equilivant of ISO 320 +3db is the equilivant of ISO 400 +6dbis the equilivant of ISO 800 +12db is the equilivant of ISO 1250 +18db is the equilivant of ISO 2500+ I tested them with the default camera settings and a shutter speed of 1/50 with the mode select set to HD (50i). I also tested the Panalook custom preset and got the same results at -3db and 0db. I am sure there will be custom presets that do impact the results but I have not tested all of them yet. I am going to do more extensive testing later on. The results seem right as I heard before that the Canon XL-H1 had a ISO rating of 320. My only question is what is the difference between -3db and 0db in terms of image quality? With -3db, the camera should rate ISO 200. So is there a penalty I pay in terms of image quality? Otherwise, I will use the -3db setting whenever possible and only go up when there is not enough light. At least I have a good starting point now.

January 16th, 2007, 10:26 AM	#19
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	Interesting! Thanks for doing that work. The only difference you should see between -3 dB and 0 dB gain settings is a bit more noise at 0. You'll have to decide for yourself whether you want the speed and can live with the noise or can't tolerate the noise and will sacrifice the speed. In well lit situations it should make very little difference which setting is used. In natural light situations look for the noise in shadow areas as that is where it will be most prevalent though in some scenes (indoor at night w/o supplemental lighting) the whole frame may be "crawling" with noise.

January 16th, 2007, 11:10 AM	#20
Floris van Eck Major Player Join Date: Jan 2006 Location: The Netherlands Posts: 993	The strange thing is: why would they call it -3db? As I see it, -3db should have been 0db and +18db should have been +36. The minus gain number makes no sense to me. So I suspected that 0db is the lowest setting and -3db does add some trickery to go even lower. Now you have -3db which is the lowest factor... then you have the A (Auto Gain) and then 0db. I just think they could and should have done this in a different way. I am currently shooting theatre. The play is called "Mistero Buffo" and only has white lighting. So everything is black or white to say so. I did some tests and you really see the increased noise in higher gain settings. Like you said, the black areas are the worst in terms of grain.

January 16th, 2007, 01:06 PM	#21
Shawn Alyasiri Major Player Join Date: Sep 2005 Location: Bloomington, IL Posts: 256	"this one goes to 11..." :)

January 16th, 2007, 02:48 PM	#22
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	Gain is a relative thing i.e. it must always be specified relative to some reference point in the system. As we are not being told what the referernce point is the absolute gain is meaningless. It is probable that the labels represents the gain of an amplifier some where in the middle of the chain and that the numbers are the actual gain of this amplifier (i.e. the reference point is it's input). -3dB gain means that if you put 141 millivolts in you get 100 millivolts out (that's right - it doesn't amplify, it attenuates). 0 dB would mean 141 mV in gives 141 mV out, +3 dB would mean 200 mV out for 141 mV in etc.