White Balance Issue at DVinfo.net

Jeff Milligan · August 24th, 2005, 03:49 PM

I interviewed a person (head and shoulders view) at a desk under a mix of overhead fluorescent (sp?) lights and an on-camera 10 watt light. I did a custom white balance which seemed to work as usual. The EVF view also looked good. When I looked the clips afterwards on the editing monitor, there is a slow cycle of changing white balance from slightly cool to slighty warm that repeats throughout all of these clips. An interview right after that at another location with a mix of some diffused window light and the same on-camera light was fine.

I have not ever had this happen on the XL1s or the GL2. Does the XL2 continue looking for a balance after the WB indicator has stopped blinking? Any help would be appreciated. I want to prevent this from happening in the future. I also have to figure out how to deal with this in post production to use these clips.

Kelly Wilbur · August 24th, 2005, 05:21 PM

Hi Jeff,

This isn't a white balance issue...it is a shutter speed issue. If your shutter speed is set high under flourescent lights, you will see the effect you got. You need to slow your shutter speed down in order to blend together the refresh rate of the lights.

This will only happen with flourescent lights. The same thing happens when you shoot a TV with a high shutter speed. Your shutter will be out of synch with the refresh rate of the TV and you will see a black band move across the picture. Same concept.

Kelly

Jeff Milligan · August 24th, 2005, 06:58 PM

Thanks Kelly for this information. What shutter speed guidelines would you recommend to avoid this effect?

This makes sense since the fluorescent lighting was the main light and the on camera light was more of a fill. I was shooting with a narrow depth of field to reduce the distractions in the background. This would raise the shutter speed.

I have shot under fluorescent lights before without this effect but not with this lighting combination for catch lights in the eyes and to open up the dark shadows under the eyes from overhead lighting.

A. J. deLange · August 26th, 2005, 02:28 PM

Fluorescent lights go through a cycle of color temperature with each half cycle of the power line which lasts 1/120th of a second (in the US) so shutter speeds of 1/60th or 1/30th will cover more than a complete color cycle and should take care of most of the problem.

Jeff Milligan · August 26th, 2005, 03:47 PM

Thanks A.J. for the information about shutter speed settings. I will experiment with the ND filter to see how to shoot for narrow depth of field and the shutter speeds.

Stephanie Wilson · August 27th, 2005, 01:37 AM

Yes,

I blew a very important interview using a shutter speed of 500 while the studio fluorescent lights were on. Even though I used some additional stand lights the video looked like a freakin kaleidoscope and was totally unusable. Unless of course, the audience was on acid and might enjoy the show..... Unfortunately they weren't....

Steph

Graham Bernard · August 27th, 2005, 05:17 AM

Stephanie? I wonder if there is a way to "pull-back" your "ditched" video work. How about making two tracks, one with reversed field order. I use Vegas, maybe putting the same event one on top of the other and reversing the field order .. just a thought . .hmmm.. maybe a Vegas script could "do" something?

Just a thought - Grazie

Jeffrey Thayer · August 27th, 2005, 09:18 AM

I do a lot of xl2 shooting of hockey games under mercury and flourescent lighting. Every game is different and every rink is different. I use warm cards and white balancing extensively. I use the light blue and the light green cards to balance and it generally helps.

Jean-Francois Robichaud · September 24th, 2005, 10:14 AM

Now, this is very interesting. Last saturday, I shot a scene in a fast-food restaurant, under fluorescent lighting plus my own soft light source. I was wondering why the colour phase was slowly pulsating on the final image (warm-cold-warm-cold). I now understand my mistake: I used a fast shutter speed, and I can see how using a slower one would have evened out the effect. I should have known better! I solemny swear that from now on, I shall always use 1/60, unless the situation really calls for something different.

Last June, I shot a movie in Germany with my NTSC camera, under 50Hz cheap light fixtures. The strobing effect because of frequency mismatch is horrible. I know this is different, and I can't remember if I used 1/60 or not. If I didn't, I wonder if it would have helped...

Gustavo Godinho · February 16th, 2006, 11:33 AM

It happened to me some days ago and I was worried about the possibility of a camera problem.

I was shooting with a 300W as backlight, a 650W very diffused as key and a 650W fresnel to light the background, a little diffused. The room had some flo lights (ceiling) and after setting the white balance, the problem began. I said to the guy being the interviewed: "just a moment, I have to make a litte adjustment", and I just couldn´t find a way to fix the problem. I used the camera white balance presets and it was happening even on those modes!! Then, I changed to AUTO mode and the problem was gone. I´m not sure what was the shutter speed at the time, but I *THINK* i tested slower shutter speeds. Can´t remember now.

Do you guys think that the camera shooting a person lit with sronger lights, the flo lights on the ceiling could cause that?

August 24th, 2005, 03:49 PM	#1
Jeff Milligan Regular Crew Join Date: Aug 2005 Location: Keizer, Oregon Posts: 26	White Balance Issue I interviewed a person (head and shoulders view) at a desk under a mix of overhead fluorescent (sp?) lights and an on-camera 10 watt light. I did a custom white balance which seemed to work as usual. The EVF view also looked good. When I looked the clips afterwards on the editing monitor, there is a slow cycle of changing white balance from slightly cool to slighty warm that repeats throughout all of these clips. An interview right after that at another location with a mix of some diffused window light and the same on-camera light was fine. I have not ever had this happen on the XL1s or the GL2. Does the XL2 continue looking for a balance after the WB indicator has stopped blinking? Any help would be appreciated. I want to prevent this from happening in the future. I also have to figure out how to deal with this in post production to use these clips.

August 24th, 2005, 05:21 PM	#2
Kelly Wilbur Regular Crew Join Date: May 2005 Location: Indianapolis Indiana Posts: 109	Hi Jeff, This isn't a white balance issue...it is a shutter speed issue. If your shutter speed is set high under flourescent lights, you will see the effect you got. You need to slow your shutter speed down in order to blend together the refresh rate of the lights. This will only happen with flourescent lights. The same thing happens when you shoot a TV with a high shutter speed. Your shutter will be out of synch with the refresh rate of the TV and you will see a black band move across the picture. Same concept. Kelly __________________ ------------------------- Partial Equipment List: Canon XL2 w/ 20X zoom Bogen/Manfrotto 516 Pro fluid head Bogen/Manfrotto 3246 legs Panasonic PATC7WMS1 7" LCD PowerMac G5 2.7 GHz OS X Tiger 2 GB RAM, 400 GB SATA ATI Radeon 9600 Dell 2405FPW 24" LCD Final Cut Pro 5.0 Studio

August 24th, 2005, 06:58 PM	#3
Jeff Milligan Regular Crew Join Date: Aug 2005 Location: Keizer, Oregon Posts: 26	Recommendations for Shutter Speed Range Thanks Kelly for this information. What shutter speed guidelines would you recommend to avoid this effect? This makes sense since the fluorescent lighting was the main light and the on camera light was more of a fill. I was shooting with a narrow depth of field to reduce the distractions in the background. This would raise the shutter speed. I have shot under fluorescent lights before without this effect but not with this lighting combination for catch lights in the eyes and to open up the dark shadows under the eyes from overhead lighting.

August 27th, 2005, 09:18 AM	#8
Jeffrey Thayer New Boot Join Date: Dec 2004 Location: Charlotte, Vermont Posts: 6	Flourescent lighting and warm cards I do a lot of xl2 shooting of hockey games under mercury and flourescent lighting. Every game is different and every rink is different. I use warm cards and white balancing extensively. I use the light blue and the light green cards to balance and it generally helps. __________________ Jeffrey Thayer ReGenesis Productions

February 16th, 2006, 11:33 AM	#10
Gustavo Godinho Regular Crew Join Date: Feb 2004 Location: Belém - Pa - Brazil Posts: 130	It happened to me some days ago and I was worried about the possibility of a camera problem. I was shooting with a 300W as backlight, a 650W very diffused as key and a 650W fresnel to light the background, a little diffused. The room had some flo lights (ceiling) and after setting the white balance, the problem began. I said to the guy being the interviewed: "just a moment, I have to make a litte adjustment", and I just couldn´t find a way to fix the problem. I used the camera white balance presets and it was happening even on those modes!! Then, I changed to AUTO mode and the problem was gone. I´m not sure what was the shutter speed at the time, but I THINK i tested slower shutter speeds. Can´t remember now. Do you guys think that the camera shooting a person lit with sronger lights, the flo lights on the ceiling could cause that? __________________ lml

August 26th, 2005, 02:28 PM	#4
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	Fluorescent lights go through a cycle of color temperature with each half cycle of the power line which lasts 1/120th of a second (in the US) so shutter speeds of 1/60th or 1/30th will cover more than a complete color cycle and should take care of most of the problem.

August 26th, 2005, 03:47 PM	#5
Jeff Milligan Regular Crew Join Date: Aug 2005 Location: Keizer, Oregon Posts: 26	Thanks A.J. for the information about shutter speed settings. I will experiment with the ND filter to see how to shoot for narrow depth of field and the shutter speeds.

August 27th, 2005, 01:37 AM	#6
Stephanie Wilson Major Player Join Date: May 2005 Location: Sherman Oaks CA Posts: 255	Yes, I blew a very important interview using a shutter speed of 500 while the studio fluorescent lights were on. Even though I used some additional stand lights the video looked like a freakin kaleidoscope and was totally unusable. Unless of course, the audience was on acid and might enjoy the show..... Unfortunately they weren't.... Steph

August 27th, 2005, 05:17 AM	#7
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Stephanie? I wonder if there is a way to "pull-back" your "ditched" video work. How about making two tracks, one with reversed field order. I use Vegas, maybe putting the same event one on top of the other and reversing the field order .. just a thought . .hmmm.. maybe a Vegas script could "do" something? Just a thought - Grazie

September 24th, 2005, 10:14 AM	#9
Jean-Francois Robichaud Regular Crew Join Date: Sep 2005 Location: Montreal, Canada Posts: 142	Now, this is very interesting. Last saturday, I shot a scene in a fast-food restaurant, under fluorescent lighting plus my own soft light source. I was wondering why the colour phase was slowly pulsating on the final image (warm-cold-warm-cold). I now understand my mistake: I used a fast shutter speed, and I can see how using a slower one would have evened out the effect. I should have known better! I solemny swear that from now on, I shall always use 1/60, unless the situation really calls for something different. Last June, I shot a movie in Germany with my NTSC camera, under 50Hz cheap light fixtures. The strobing effect because of frequency mismatch is horrible. I know this is different, and I can't remember if I used 1/60 or not. If I didn't, I wonder if it would have helped...