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senojobmij · 02-09-2009, 07:28 PM

I have a quick question about using the gray card and color temperature.

I was at Zion national park this weekend and I was shooting some pics I placed my gray card on the ground to use it as a in Lightroom for post processing.

In Lightroom, using the white balance tool shows the gray card at 50000k, with +2 tint. Does this temperature sound reasonable? The pictures look OK with this reading, I just wanted to make sure this wasn't a issue with the way I was using the gray card. From what I've read normal WB ranges are in the 3000-10000 range.

The day was overcast, and it was near sunset. Below is a sample picture.

http://www.flickr.com/photos/senojobmij/3268434062/sizes/m/

On another note, I didn't notice the K10D took this at 1/20 sec handheld until just
now. Go SR I suppose.

Let me know what you think, thanks.

deaner · 02-09-2009, 07:33 PM

I don't check white balance with a gray card; I use a bright white cloth. Here is a link that describes it better than I could.

Photography Rulez: K10D Manual White Balance

SpecialK · 02-09-2009, 07:51 PM

If the gray is neutral, it will work fine. I assume you meant 5,000 and not 50,000K?.

senojobmij · 02-09-2009, 10:38 PM

Originally posted by SpecialK

If the gray is neutral, it will work fine. I assume you meant 5,000 and not 50,000K?.

No, I meant 50,000k.

I think it might just be some wierd Lightroom thing, but even just clicking around the pictures with the whitebalance tool and the majority of the color temperatures it's indicating are in the 20,000k+ range... I was just confused since this seems high, even though the pictures, to my eyes, look normal.

Playing with Lightroom, I can't really tell the difference between 20,000k and 50,000k, so maybe its something buggy with Windows 7 and Lightroom 64bit.

cupic · 02-10-2009, 05:59 AM

Thanks for the link

cheers

AndrewShirley · 02-10-2009, 06:25 AM

I personally wouldn`t use anything but a grey card at this point (possibly a Whibal). I usually set the white balance before taking shots so that I can guage colours real time during the shoot.

An 18% grey card is supposed to be neutral and are probably a lot closer than some hunk of old sock you find in a drawer

But as they say, close enough for rock and roll.

I worry about using something white for balancing due to the risk of over-exposing during the white-balance reading. If that happens then your camera will think that no adjustment is needed and your white-balance will be entirely wrong. Even if you only clip 1 or 2 channels, your WB is still wrong.

- Andrew

Dubious Drewski · 06-13-2009, 08:09 PM

Originally posted by deaner

I don't check white balance with a gray card; I use a bright white cloth.

As stated, don't use pure white to do white balance. Use neutral gray. Using white will surprisingly give you a wrong balance now and then, because of blown channels.

jeffkrol · 06-13-2009, 09:17 PM

Originally posted by senojobmij

No, I meant 50,000k.

I think it might just be some wierd Lightroom thing, but even just clicking around the pictures with the whitebalance tool and the majority of the color temperatures it's indicating are in the 20,000k+ range... I was just confused since this seems high, even though the pictures, to my eyes, look normal.

Playing with Lightroom, I can't really tell the difference between 20,000k and 50,000k, so maybe its something buggy with Windows 7 and Lightroom 64bit.

Other processors have had color temp anomalies w/ Pentax files... This would not be out of the realm of possibilities. 50000 is just plain wrong.
Any Lightroom updats currently available.

**David** · 06-14-2009, 04:09 AM

Originally posted by AndrewShirley

An 18% grey card is supposed to be neutral and are probably a lot closer than some hunk of old sock you find in a drawer

But as they say, close enough for rock and roll.

- Andrew

Your use of 18% for gray cards triggered and old memory from Photo Dip days. This link says it all Meters Don't See 18% Gray by Thom Hogan.

FWIW I have stopped using gray cards and now use the folding white devices with good results.

David

WheresWaldo · 06-14-2009, 08:12 AM

Originally posted by David

Your use of 18% for gray cards triggered and old memory from Photo Dip days. This link says it all Meters Don't See 18% Gray by Thom Hogan.

FWIW I have stopped using gray cards and now use the folding white devices with good results.

David

Sorry if this is OT but with regard to what the sensor sees as neutral gray. I noticed that in the discussion of uniWB they specifically speak of a magenta color as what the sensor sees as Neutral, I am wondering why no one is building a neutral magenta card to set exposure.

GUILLERMO LUIJK >> TUTORIALS >> UNIWB. MAKE CAMERA DISPLAY RELIABLE

jeffkrol · 06-14-2009, 01:02 PM

Originally posted by WheresWaldo

Sorry if this is OT but with regard to what the sensor sees as neutral gray. I noticed that in the discussion of uniWB they specifically speak of a magenta color as what the sensor sees as Neutral, I am wondering why no one is building a neutral magenta card to set exposure.

GUILLERMO LUIJK >> TUTORIALS >> UNIWB. MAKE CAMERA DISPLAY RELIABLE

This technique is really only for WB and neutralizing your histogram. It's not technically exposure related.
It would only be good for daylight and flash (technically only for particular cameras and particular light). You need a cyan card for tungsten. Also you need to either filter your light or lens w/ the same filter.
The uneven sensitivity of silicon is what causes your camera to use "channel multipliers"... you really want them set to 1:1:1 but the only way to do that is increase r/b (in daylight/flash) and or decrease green. This is what the magenta filter does.... Then you can increase exposure to compensate.

WheresWaldo · 06-14-2009, 04:10 PM

Thanks for the explanation, I was just thinking out loud here and see by your explanation that it really wouldn't work like how I expected. Guess I'll stick with a Gray Card.

**Ron Boggs** · 06-16-2009, 09:25 PM

A couple months ago I did a little test in tungsten lighting comparing use of gray card (actually gray Pelican case) and white paper. The setting from the gray card was much closer to neutral than the white which came out a bit warm--still influenced by the tungsten? Had intended to test outdoors in shade, under haze and in sunlight but never bothered--shooting mostly film this past month or so...The result was enough to steer me toward gray rather than white, but again, still need outdoor tests to really "sell" me. Since the perception of color is pretty subjective, I'd say test gray and white for yourself and use whichever you prefer...both were better than any of the in-camera white balance presets.

02-09-2009, 07:28 PM	#1
senojobmij New Member Join Date: Dec 2008 Location: Las Vegas Posts: 6	Color temperature with gray card I have a quick question about using the gray card and color temperature. I was at Zion national park this weekend and I was shooting some pics I placed my gray card on the ground to use it as a in Lightroom for post processing. In Lightroom, using the white balance tool shows the gray card at 50000k, with +2 tint. Does this temperature sound reasonable? The pictures look OK with this reading, I just wanted to make sure this wasn't a issue with the way I was using the gray card. From what I've read normal WB ranges are in the 3000-10000 range. The day was overcast, and it was near sunset. Below is a sample picture. http://www.flickr.com/photos/senojobmij/3268434062/sizes/m/ On another note, I didn't notice the K10D took this at 1/20 sec handheld until just now. Go SR I suppose. Let me know what you think, thanks.

06-14-2009, 01:02 PM	#11
jeffkrol Veteran Member Join Date: Sep 2006 Location: Wisconsin USA Photos: Gallery Posts: 8,434	R Originally posted by WheresWaldo Sorry if this is OT but with regard to what the sensor sees as neutral gray. I noticed that in the discussion of uniWB they specifically speak of a magenta color as what the sensor sees as Neutral, I am wondering why no one is building a neutral magenta card to set exposure. GUILLERMO LUIJK >> TUTORIALS >> UNIWB. MAKE CAMERA DISPLAY RELIABLE This technique is really only for WB and neutralizing your histogram. It's not technically exposure related. It would only be good for daylight and flash (technically only for particular cameras and particular light). You need a cyan card for tungsten. Also you need to either filter your light or lens w/ the same filter. The uneven sensitivity of silicon is what causes your camera to use "channel multipliers"... you really want them set to 1:1:1 but the only way to do that is increase r/b (in daylight/flash) and or decrease green. This is what the magenta filter does.... Then you can increase exposure to compensate.

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02-09-2009, 07:33 PM	#2
deaner Junior Member Join Date: Jan 2008 Location: Missouri, USA Posts: 25	I don't check white balance with a gray card; I use a bright white cloth. Here is a link that describes it better than I could. Photography Rulez: K10D Manual White Balance

02-09-2009, 07:51 PM	#3
SpecialK Pentaxian Join Date: Dec 2006 Location: So California Photos: Gallery Posts: 16,482	If the gray is neutral, it will work fine. I assume you meant 5,000 and not 50,000K?.

02-09-2009, 10:38 PM	#4
senojobmij New Member Join Date: Dec 2008 Location: Las Vegas Posts: 6 Original Poster	Originally posted by SpecialK If the gray is neutral, it will work fine. I assume you meant 5,000 and not 50,000K?. No, I meant 50,000k. I think it might just be some wierd Lightroom thing, but even just clicking around the pictures with the whitebalance tool and the majority of the color temperatures it's indicating are in the 20,000k+ range... I was just confused since this seems high, even though the pictures, to my eyes, look normal. Playing with Lightroom, I can't really tell the difference between 20,000k and 50,000k, so maybe its something buggy with Windows 7 and Lightroom 64bit.

02-10-2009, 05:59 AM	#5
cupic Veteran Member Join Date: Apr 2008 Location: Australia-NSW Photos: Gallery Posts: 4,824	Thanks for the link cheers

02-10-2009, 06:25 AM	#6
AndrewShirley Inactive Account Join Date: Mar 2007 Location: Barrie, Ontario, Canada Posts: 421	I personally wouldn`t use anything but a grey card at this point (possibly a Whibal). I usually set the white balance before taking shots so that I can guage colours real time during the shoot. An 18% grey card is supposed to be neutral and are probably a lot closer than some hunk of old sock you find in a drawer But as they say, close enough for rock and roll. I worry about using something white for balancing due to the risk of over-exposing during the white-balance reading. If that happens then your camera will think that no adjustment is needed and your white-balance will be entirely wrong. Even if you only clip 1 or 2 channels, your WB is still wrong. - Andrew

06-13-2009, 08:09 PM	#7
Dubious Drewski Forum Member Join Date: Mar 2008 Location: Calgary Posts: 67	Originally posted by deaner I don't check white balance with a gray card; I use a bright white cloth. As stated, don't use pure white to do white balance. Use neutral gray. Using white will surprisingly give you a wrong balance now and then, because of blown channels.

06-13-2009, 09:17 PM	#8
jeffkrol Veteran Member Join Date: Sep 2006 Location: Wisconsin USA Photos: Gallery Posts: 8,434	Originally posted by senojobmij No, I meant 50,000k. I think it might just be some wierd Lightroom thing, but even just clicking around the pictures with the whitebalance tool and the majority of the color temperatures it's indicating are in the 20,000k+ range... I was just confused since this seems high, even though the pictures, to my eyes, look normal. Playing with Lightroom, I can't really tell the difference between 20,000k and 50,000k, so maybe its something buggy with Windows 7 and Lightroom 64bit. Other processors have had color temp anomalies w/ Pentax files... This would not be out of the realm of possibilities. 50000 is just plain wrong. Any Lightroom updats currently available.

06-14-2009, 04:09 AM	#9
David Site Supporter Join Date: Jul 2007 Location: Sandy Bay, Tasmania, Australia Photos: Albums Posts: 347	Originally posted by AndrewShirley An 18% grey card is supposed to be neutral and are probably a lot closer than some hunk of old sock you find in a drawer But as they say, close enough for rock and roll. - Andrew Your use of 18% for gray cards triggered and old memory from Photo Dip days. This link says it all Meters Don't See 18% Gray by Thom Hogan. FWIW I have stopped using gray cards and now use the folding white devices with good results. David

06-14-2009, 08:12 AM	#10
WheresWaldo Veteran Member Join Date: Sep 2006 Location: North Carolina Photos: Gallery Posts: 498	Originally posted by David Your use of 18% for gray cards triggered and old memory from Photo Dip days. This link says it all Meters Don't See 18% Gray by Thom Hogan. FWIW I have stopped using gray cards and now use the folding white devices with good results. David Sorry if this is OT but with regard to what the sensor sees as neutral gray. I noticed that in the discussion of uniWB they specifically speak of a magenta color as what the sensor sees as Neutral, I am wondering why no one is building a neutral magenta card to set exposure. GUILLERMO LUIJK >> TUTORIALS >> UNIWB. MAKE CAMERA DISPLAY RELIABLE

06-14-2009, 04:10 PM	#12
WheresWaldo Veteran Member Join Date: Sep 2006 Location: North Carolina Photos: Gallery Posts: 498	Thanks for the explanation, I was just thinking out loud here and see by your explanation that it really wouldn't work like how I expected. Guess I'll stick with a Gray Card.

06-16-2009, 09:25 PM	#13
Ron Boggs Site Supporter Join Date: Feb 2008 Location: MT Photos: Gallery Posts: 1,350	A couple months ago I did a little test in tungsten lighting comparing use of gray card (actually gray Pelican case) and white paper. The setting from the gray card was much closer to neutral than the white which came out a bit warm--still influenced by the tungsten? Had intended to test outdoors in shade, under haze and in sunlight but never bothered--shooting mostly film this past month or so...The result was enough to steer me toward gray rather than white, but again, still need outdoor tests to really "sell" me. Since the perception of color is pretty subjective, I'd say test gray and white for yourself and use whichever you prefer...both were better than any of the in-camera white balance presets.

Color temperature with gray card

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