Black Balance?

Alister Chapman · December 9th, 2009, 02:04 AM

Black balance should not have a notcable effect on white balance or colours. Setting the black balance sets the black levels of the R, G and B channels so that they are all at zero. Unless it is grossely off it should not change the cameras colour balance, which is a function of R, G, and B gain as opposed to black balances simple zero level set. There can be a tiny hints of coloration in near black parts of the picture with very poor black balance but there certainly should not be any effect to mid tones or other parts of the image.

Leonard Levy · December 9th, 2009, 12:16 PM

I'm not sure that my magenta hued preset is due only to poor black balance. In practice I haven't noticed that the blacks were off but the whites are clearly magenta. Of course I haven't really looked carefully at the blacks. I didn't notice any of this till I got on a vectorscope.

It seems that the preset has a matrix and color balance all its own independent of the PP settings that underlie any other changes you set in the camera. In a more expensive camera those are adjustable as well. Too bad I can't at least do a black balance. Funny though, until I looked at the vectorscope I never noticed how off it was and used preset fairly often with nary a complaint.

The camera just came back from Sony repair so I'm not totally sure it was a pre-existing condition though - might be from a new board. Maybe I should call Sony.

Alister Chapman · December 9th, 2009, 02:22 PM

My EX3 and EX1 both have very good colour response with no hue or colour cast. I would suggest a megenta colour cast using presets is abnormal.

Michael B. McGee · December 9th, 2009, 06:19 PM

Quote:

Originally Posted by Michael B. McGee

i had a back focus problem today on set with a rented EX3 as B-camera. this made wonder about my own EX1 and its own Back Focus. when looking in the maintenance menu i became aware that the "Auto FB Adjust" and "Auto BLK Balance" were greyed out. has anyone with v1.11_0531 had success adjusting one or both of these procedures?

just want to remind everyone about my inquiry?
thanks.

Tom Roper · December 9th, 2009, 06:33 PM

Quote:

Originally Posted by Michael B. McGee

just want to remind everyone about my inquiry?
thanks.

Quote:

Originally Posted by Michael B. McGee

i had a back focus problem today on set with a rented EX3 as B-camera. this made wonder about my own EX1 and its own Back Focus. when looking in the maintenance menu i became aware that the "Auto FB Adjust" and "Auto BLK Balance" were greyed out. has anyone with v1.11_0531 had success adjusting one or both of these procedures?

For the Auto FB Adjustment, make sure the focus ring is forward and the barrel switch in auto. The cam cannot do an Auto FB adjust if the lens focus is in manual mode.

Michael B. McGee · December 9th, 2009, 07:07 PM

thanks tom, but i've done that and still can't access/perform it.

Tom Roper · December 9th, 2009, 09:16 PM

That's disappointing Michael. A couple things you've probably also tried, but I would put the menu display on partial, the iris switch to auto, and shutter auto switch to on.

I assume you also reset all.

From the description you gave in the other thread about the backfocus, it's pretty imperative to get the flange back calibration working.

I checked my firmware version just now, same as yours, FB and BB not grayed out.

Michael B. McGee · December 10th, 2009, 06:36 PM

i haven't done an all reset yet or any of the other suggestions you mentioned. i'll try it again tonight. thanks for responding.

Michael B. McGee · December 11th, 2009, 01:26 AM

EUREKA!!! I found it!

so, note to all who are trying to perform a Auto FB Adjust you must:
1. place the lens focus ring forward(auto)
2. switch focus switch to auto
3. zoom must be in servo
4. iris set to auto

i think that's all.

still can't perform an Auto BLK Balance though

Twan Neman · March 11th, 2010, 05:09 AM

I've managed to get into the maintenance menu, but which menu-option do I need to select to perform auto black balance ?

Is it MN > Black Shading > Auto BLK Shad ? Just want to make sure i got the correct one.

Doug Jensen · March 11th, 2010, 07:25 AM

Why bother? The camera automatically does a black balance everytime you turn it on.

Twan Neman · March 11th, 2010, 08:06 AM

I wish it did. I've got A LOT of noise in my black levels when shooting footage. I was told that resetting / calibrating the black levels would solve the problem, just want to make sure I got the correct menu option.

Doug Jensen · March 11th, 2010, 12:17 PM

I doubt that noise in your black levels has anything do to with the black balance. Black balance is for color.

Olof Ekbergh · March 11th, 2010, 12:28 PM

Twan, like Doug said, black balance is done each time the camera is turned on.

If your shadows are noisy, it probably is the way your camera is set up. I find Profile 4 is noisy. Also make sure your gain is 0 or -3. Black stretch will also affect noise.

The EXcams do have a bit of noise, much better than most cameras in this price range. The truth is we are really spoiled these days. A lot of people feel CCD's are less noisy and maybe they are especially 2/3" CCD's.

I think the EX cams are really the first inexpensive HD cameras that have decent low light performance.

Best way to get rid of noise is to not underexpose. And not boost the gain. Also mess with your profiles.

Jack Zhang · January 25th, 2012, 09:03 AM

Sorry for bumping this thread, but I was going through the EX1R Maintenance Menu and the Auto Black Balance option for some reason only executes in interlaced mode.

Hope that eliminates some confusion, you now know that if you shoot interlaced, and you know how to get to the service menus, you can do an auto black balance on the EX1R.

December 9th, 2009, 02:04 AM	#16
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	Black balance should not have a notcable effect on white balance or colours. Setting the black balance sets the black levels of the R, G and B channels so that they are all at zero. Unless it is grossely off it should not change the cameras colour balance, which is a function of R, G, and B gain as opposed to black balances simple zero level set. There can be a tiny hints of coloration in near black parts of the picture with very poor black balance but there certainly should not be any effect to mid tones or other parts of the image. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

December 9th, 2009, 02:22 PM	#18
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	My EX3 and EX1 both have very good colour response with no hue or colour cast. I would suggest a megenta colour cast using presets is abnormal. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

December 11th, 2009, 01:26 AM	#24
Michael B. McGee Major Player Join Date: Nov 2008 Location: Santa Monica, CA Posts: 318	Auto FB Adjust settings EUREKA!!! I found it! so, note to all who are trying to perform a Auto FB Adjust you must: 1. place the lens focus ring forward(auto) 2. switch focus switch to auto 3. zoom must be in servo 4. iris set to auto i think that's all. still can't perform an Auto BLK Balance though Last edited by Michael B. McGee; December 11th, 2009 at 01:26 AM. Reason: spelling

March 11th, 2010, 07:25 AM	#26
Doug Jensen Vortex Media Join Date: Jan 2009 Location: Florida Posts: 3,417	Why bother? The camera automatically does a black balance everytime you turn it on. __________________ Vortex Media http://www.vortexmedia.com/ Sony FS7, F55, and XDCAM training videos, field guides, and other production tools

March 11th, 2010, 12:17 PM	#28
Doug Jensen Vortex Media Join Date: Jan 2009 Location: Florida Posts: 3,417	I doubt that noise in your black levels has anything do to with the black balance. Black balance is for color. __________________ Vortex Media http://www.vortexmedia.com/ Sony FS7, F55, and XDCAM training videos, field guides, and other production tools

December 9th, 2009, 12:16 PM	#17
Leonard Levy Trustee Join Date: Feb 2006 Location: USA Posts: 1,684	I'm not sure that my magenta hued preset is due only to poor black balance. In practice I haven't noticed that the blacks were off but the whites are clearly magenta. Of course I haven't really looked carefully at the blacks. I didn't notice any of this till I got on a vectorscope. It seems that the preset has a matrix and color balance all its own independent of the PP settings that underlie any other changes you set in the camera. In a more expensive camera those are adjustable as well. Too bad I can't at least do a black balance. Funny though, until I looked at the vectorscope I never noticed how off it was and used preset fairly often with nary a complaint. The camera just came back from Sony repair so I'm not totally sure it was a pre-existing condition though - might be from a new board. Maybe I should call Sony.

December 9th, 2009, 07:07 PM	#21
Michael B. McGee Major Player Join Date: Nov 2008 Location: Santa Monica, CA Posts: 318	thanks tom, but i've done that and still can't access/perform it.

December 9th, 2009, 09:16 PM	#22
Tom Roper Trustee Join Date: Jun 2004 Location: Denver, Colorado Posts: 1,891	That's disappointing Michael. A couple things you've probably also tried, but I would put the menu display on partial, the iris switch to auto, and shutter auto switch to on. I assume you also reset all. From the description you gave in the other thread about the backfocus, it's pretty imperative to get the flange back calibration working. I checked my firmware version just now, same as yours, FB and BB not grayed out.

December 10th, 2009, 06:36 PM	#23
Michael B. McGee Major Player Join Date: Nov 2008 Location: Santa Monica, CA Posts: 318	i haven't done an all reset yet or any of the other suggestions you mentioned. i'll try it again tonight. thanks for responding.

March 11th, 2010, 05:09 AM	#25
Twan Neman Tourist Join Date: Mar 2010 Location: Hilversum, the Netherlads Posts: 2	I've managed to get into the maintenance menu, but which menu-option do I need to select to perform auto black balance ? Is it MN > Black Shading > Auto BLK Shad ? Just want to make sure i got the correct one.

March 11th, 2010, 08:06 AM	#27
Twan Neman Tourist Join Date: Mar 2010 Location: Hilversum, the Netherlads Posts: 2	I wish it did. I've got A LOT of noise in my black levels when shooting footage. I was told that resetting / calibrating the black levels would solve the problem, just want to make sure I got the correct menu option.

March 11th, 2010, 12:28 PM	#29
Olof Ekbergh Sponsor: Westside AV Join Date: Dec 2008 Location: Mount Washington Valley, NH, USA Posts: 1,365	Twan, like Doug said, black balance is done each time the camera is turned on. If your shadows are noisy, it probably is the way your camera is set up. I find Profile 4 is noisy. Also make sure your gain is 0 or -3. Black stretch will also affect noise. The EXcams do have a bit of noise, much better than most cameras in this price range. The truth is we are really spoiled these days. A lot of people feel CCD's are less noisy and maybe they are especially 2/3" CCD's. I think the EX cams are really the first inexpensive HD cameras that have decent low light performance. Best way to get rid of noise is to not underexpose. And not boost the gain. Also mess with your profiles.

January 25th, 2012, 09:03 AM	#30
Jack Zhang Inner Circle Join Date: May 2005 Location: Burnaby, BC, Canada Posts: 3,053	Re: Black Balance? Sorry for bumping this thread, but I was going through the EX1R Maintenance Menu and the Auto Black Balance option for some reason only executes in interlaced mode. Hope that eliminates some confusion, you now know that if you shoot interlaced, and you know how to get to the service menus, you can do an auto black balance on the EX1R.