White Balance: Episdode II

Peter Koller · March 28th, 2002, 12:34 PM

I am totally enlighted and illuminated now.

Thank you for your input Bryan!

Cheers,

Bryan Johannes Onel · March 28th, 2002, 04:20 PM

<<<--
Bryan,

An 18% gray card was recommended because it is at 50 IRE's. Flesh tones are supposedly at 75 IRE's and if one were to balance to a pure white they would not look as good as a balance to the 18% grey.

a grey card is very important for exposure to find the exact zone 5 in film, im a film person, i don't work with IRE, on film you cannot measure how much it will be lit, you can only estimate, thats what the zone system is for. but for the white balance thing, 18% grey card is zone 5 so it doesn't reflect all the light it receives, you can indeed white balance with a grey card, but it doesn't reflect all the color it receives, so that is an issue. if we wouldn't care about reflectance we would try to balance the whites on a black card ! :P
but for video 18% can indeed be used. but please use filters for consistency!!!

I hope we haven't taken up too much of your time Bryan.

i will send you the bill :)
just kidding, you haven't taken too much of my time, i don't have any jobs now anyway, just boring myself, so i could as well help you guys.

C ya.

Bill Ravens · March 28th, 2002, 04:35 PM

pure white, black, or in between(i.e.18%gray) represents a pure luma signal without any chroma. The only difference is the amplitude or intensity of the luma signal. If you white balance against an 18% gray the camera will try to take any residual chroma out of the image. Residual chroma will come from the color temperature of the lighting. If you look at the signal of white, black or any gray in between with a vectorscope, you'll see absolutely no difference. The white balance procedure simply places the luma signal at the center of the color wheel. Using an 18% gray just keeps from oversaturating the light meter the way a white surface would, yet it gives you an accurate white balance. Just my .02 worth.

Greg Matty · March 28th, 2002, 09:14 PM

I just spent half an hour with my XL-1 and the gray card. The results were not much different than balancing with just a white card.

My best result was using a 1/4 CTB gel in front of the gray card and then setting white balance. The colors might have been a little bit green but I was only using the XL-1's viewfinder so I can't say for certain. I will order a 1/8 minus green and a 1/4 minus green tomorrow. When those come in I will see if I can perfect white balance with my XL-1. If I can't I will go postal.

I was hoping I could get away with just the gray card but that doesn't seem likely now. Oh well, I have learned quite a bit in the last few days thanks to all the people at this forum. Many thanks.

Greg Matty

Bryan Johannes Onel · March 29th, 2002, 07:34 AM

greg,
like i said, with a color temp. meter all your problems will be gone, it will just say what filter to use.

Bryan Johannes Onel · March 29th, 2002, 07:40 AM

bill,
it will indeed place the luma signal at the center of the color wheel, but to get it balanced just right, you would need to have full color reflectance, 18% grey does not reflect all colors the way white does, white reflects all colors, with and 18% grey card you lose some of the colors if the light source is weak, pure white doesn't.

Greg Matty · March 29th, 2002, 10:13 AM

<<<-- Originally posted by bryanthedirector : greg,
like i said, with a color temp. meter all your problems will be gone, it will just say what filter to use. -->>>

Any idea what one of these thing-a-ma-jigs cost?

Also, this is for what filter to use on the camera itself correct? I would of course still need to set some sort of white balance though. Maybe just set it to white and if it is off, let the color temp meter tell me what to do?

Greg Matty

Bryan Johannes Onel · March 29th, 2002, 12:34 PM

Any idea what one of these thing-a-ma-jigs cost?

900 dollar for the minolta model (best one) you should try to call minolta for some discount. here is a link to some info : http://www02.bhphotovideo.com/default.sph/FrameWork.class?FNC=ProductActivator__Aproductlist_html___35492___MICM3F___USA___CatID=904___SID=ED1 9FBB4CD0

Also, this is for what filter to use on the camera itself correct?

it tells you what filter to use on the lens CC (color correction) or LB (light balancing)

I would of course still need to set some sort of white balance though.

no when using such a meter you need to stop thinking about white balance. this machine does everything for you.

Maybe just set it to white and if it is off, let the color temp meter tell me what to do?

just set your cam to 3200K or 5600K and set your color meter to that same temp.

c ya

Bryan Johannes Onel · March 29th, 2002, 05:53 PM

john and peter, your welcome! :D

Bryan Johannes Onel · March 31st, 2002, 07:53 PM

hi,
i made a mistake, lighting with film is a addictive procces, all colors mixed makes white. but still you add or substract colors.
sorry.

bye

Rob Lohman · April 1st, 2002, 10:25 AM

Bryan,

I assume you mean additive (adding) instead of addictive? Those
are very different things. Just clarifying something.

Thanks for all the explenations!

Bryan Johannes Onel · April 2nd, 2002, 12:09 AM

i did mean additive rob, i guess i was in a sleepy mood.

March 28th, 2002, 12:34 PM	#16
Peter Koller Regular Crew Join Date: Feb 2002 Location: Brunn am Gebirge, Austria Posts: 161	I am totally enlighted and illuminated now. Thank you for your input Bryan! Cheers, __________________ Peter Koller Vienna, Austria http://www.kop11.com

March 28th, 2002, 04:35 PM	#18
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	pure white, black, or in between(i.e.18%gray) represents a pure luma signal without any chroma. The only difference is the amplitude or intensity of the luma signal. If you white balance against an 18% gray the camera will try to take any residual chroma out of the image. Residual chroma will come from the color temperature of the lighting. If you look at the signal of white, black or any gray in between with a vectorscope, you'll see absolutely no difference. The white balance procedure simply places the luma signal at the center of the color wheel. Using an 18% gray just keeps from oversaturating the light meter the way a white surface would, yet it gives you an accurate white balance. Just my .02 worth. Last edited by Bill Ravens; March 28th, 2002 at 05:00 PM.

March 29th, 2002, 07:34 AM	#20
Bryan Johannes Onel Regular Crew Join Date: Mar 2002 Location: Amsterdam, The netherlands Posts: 71	greg greg, like i said, with a color temp. meter all your problems will be gone, it will just say what filter to use.

March 29th, 2002, 10:13 AM	#22
Greg Matty Regular Crew Join Date: Mar 2002 Location: Kirkland, WA Posts: 177	Re: greg <<<-- Originally posted by bryanthedirector : greg, like i said, with a color temp. meter all your problems will be gone, it will just say what filter to use. -->>> Any idea what one of these thing-a-ma-jigs cost? Also, this is for what filter to use on the camera itself correct? I would of course still need to set some sort of white balance though. Maybe just set it to white and if it is off, let the color temp meter tell me what to do? Greg Matty

March 29th, 2002, 12:34 PM	#23
Bryan Johannes Onel Regular Crew Join Date: Mar 2002 Location: Amsterdam, The netherlands Posts: 71	Re: Re: greg Any idea what one of these thing-a-ma-jigs cost? 900 dollar for the minolta model (best one) you should try to call minolta for some discount. here is a link to some info : http://www02.bhphotovideo.com/default.sph/FrameWork.class?FNC=ProductActivator__Aproductlist_html___35492___MICM3F___USA___CatID=904___SID=ED1 9FBB4CD0 Also, this is for what filter to use on the camera itself correct? it tells you what filter to use on the lens CC (color correction) or LB (light balancing) I would of course still need to set some sort of white balance though. no when using such a meter you need to stop thinking about white balance. this machine does everything for you. Maybe just set it to white and if it is off, let the color temp meter tell me what to do? just set your cam to 3200K or 5600K and set your color meter to that same temp. c ya

March 28th, 2002, 04:20 PM	#17
Bryan Johannes Onel Regular Crew Join Date: Mar 2002 Location: Amsterdam, The netherlands Posts: 71	<<<-- Bryan, An 18% gray card was recommended because it is at 50 IRE's. Flesh tones are supposedly at 75 IRE's and if one were to balance to a pure white they would not look as good as a balance to the 18% grey. a grey card is very important for exposure to find the exact zone 5 in film, im a film person, i don't work with IRE, on film you cannot measure how much it will be lit, you can only estimate, thats what the zone system is for. but for the white balance thing, 18% grey card is zone 5 so it doesn't reflect all the light it receives, you can indeed white balance with a grey card, but it doesn't reflect all the color it receives, so that is an issue. if we wouldn't care about reflectance we would try to balance the whites on a black card ! :P but for video 18% can indeed be used. but please use filters for consistency!!! I hope we haven't taken up too much of your time Bryan. i will send you the bill :) just kidding, you haven't taken too much of my time, i don't have any jobs now anyway, just boring myself, so i could as well help you guys. C ya.

March 28th, 2002, 09:14 PM	#19
Greg Matty Regular Crew Join Date: Mar 2002 Location: Kirkland, WA Posts: 177	I just spent half an hour with my XL-1 and the gray card. The results were not much different than balancing with just a white card. My best result was using a 1/4 CTB gel in front of the gray card and then setting white balance. The colors might have been a little bit green but I was only using the XL-1's viewfinder so I can't say for certain. I will order a 1/8 minus green and a 1/4 minus green tomorrow. When those come in I will see if I can perfect white balance with my XL-1. If I can't I will go postal. I was hoping I could get away with just the gray card but that doesn't seem likely now. Oh well, I have learned quite a bit in the last few days thanks to all the people at this forum. Many thanks. Greg Matty

March 29th, 2002, 07:40 AM	#21
Bryan Johannes Onel Regular Crew Join Date: Mar 2002 Location: Amsterdam, The netherlands Posts: 71	bill, it will indeed place the luma signal at the center of the color wheel, but to get it balanced just right, you would need to have full color reflectance, 18% grey does not reflect all colors the way white does, white reflects all colors, with and 18% grey card you lose some of the colors if the light source is weak, pure white doesn't.

March 29th, 2002, 05:53 PM	#24
Bryan Johannes Onel Regular Crew Join Date: Mar 2002 Location: Amsterdam, The netherlands Posts: 71	to peter and john john and peter, your welcome! :D

March 31st, 2002, 07:53 PM	#25
Bryan Johannes Onel Regular Crew Join Date: Mar 2002 Location: Amsterdam, The netherlands Posts: 71	mistake hi, i made a mistake, lighting with film is a addictive procces, all colors mixed makes white. but still you add or substract colors. sorry. bye

April 1st, 2002, 10:25 AM	#26
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	Bryan, I assume you mean additive (adding) instead of addictive? Those are very different things. Just clarifying something. Thanks for all the explenations! __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

April 2nd, 2002, 12:09 AM	#27
Bryan Johannes Onel Regular Crew Join Date: Mar 2002 Location: Amsterdam, The netherlands Posts: 71	i did mean additive rob, i guess i was in a sleepy mood.