Using A Grey & White Card For Exposure & White Balance

[@kgc2624]

This is such a perfect video. The exposure value is based on a gray card with an 18% reflectance, and "white with 93% reflectance" is +2 stop, and "black with 3% reflectance" is -2 stop. Making black look black and white look white is what gray card is for. I can't do that every time, but first I use incident light to adjust the exposure value, secondly white balancing using white, and lastly I use color checker. There is a big difference between using gray cards as the user intended in the wb space and using gray cards without knowing In the "light meter world", there are black and white at both ends, and greys live between the worlds and in the "white balance world", there are red and blue at both ends, and tungsten, fluorescent, and white lights live between the worlds.

[@COMPILOT1]

My Canon 1DxMkii manual tells me to register a custom WB, use a white card, no mention of gray. Does it make a difference on my camera? Thanks for an informative video, I have been a photographer since 1957 and just bought my first gray/white card.

[@tecraven]

It shouldn’t, but the reason I would use a white card on the Canon is because it will take exposure into account as well. But I would basically try both in a side-by-side scientific test and look at the results of both in your post production software just to confirm if it makes any difference on the Canon or not because Canon cameras still have that archaic way of setting a white balance by having to take a photograph first, which is a bit weird and convoluted. Finally, if you shoot in RAW, and you should be, you can just white balance in postproduction that way you don’t have to worry about it at the shooting stage.

[@COMPILOT1]

@@tecravenThanks for your prompt reply Cheers -- Dan.

[@robertlytch3193]

Thanks for making the video but, I have a Canon camera & does it matter ? I mean i am new to photograph & any help is more then welcome 🤔.

[@tecraven]

I have Canon equipment now as well. The make and model of the camera makes no difference whatsoever.

[@dinofareal]

What stand is that you are using to hold the White/Grey card?

[@tecraven]

It's a Hercules microphone stand with a quick grab mechanism in the middle that you just squeeze to make it higher.

[@billwdwc]

Excellent video. just saw another guys video saying set zebras to 50% for the grey side. for exposure

[@tecraven]

Hmmm, not sure why 50%, that's messed up.

[@billwdwc]

@@tecraven kzbin.info/www/bejne/Z32YpaaIhdaGeaM

[@billwdwc]

@@tecraven i think they are on about settings for skin tones

[@tecraven]

@@billwdwc Even then, you'd go about 70% and then get zebras to appear on caucasian skin tones. Lots of video guys, myself included, set zebras to 70 and then on caucasian skin tones you would allow some 'ribbons' of zebra pattern to appear on the highlighted parts of the cheeks and forehead for correct exposure.

[@billbuckleytutorials]

@@tecraven Thanks for the reply . I agree .

[@waqarmahmood7751]

Why is the metre showing 1.7 + on exposure metre if your perfectly exposed. Would u not use the grey card to obtain perfect exposure. The video is not very clear

[@tecraven]

Hi Waqar Ok, you're right, I should have explained this during the video. Basically, yes, the grey card is to achieve the correct exposure i.e. the meter at the bottom of the screen on the Sony A7 III camera would read 0.0, which is the case when I use the grey side of the card, as you can see in the video. However, the reason the exposure is reading +1.7 on the Sony screen when I'm using the white side is because the camera's metering system is assuming that the white side is in fact 18 percent grey, which I explain in the video. Now, although it is showing as +1.7 it is in fact perfectly exposed as I have the zebra stripes on the Sony set to 100, which means anything over 255 (RGB brightness levels go from 0 to 255 with 0 being black and 255 being white) will show up as zebra stripes, alerting the camera operator to the fact that these parts of the scene are overexposed. In the video I turn the shutter speed dial on the back of the camera and increase the shutter speed in one third increments from 1/25th, 1/30th, 1/40th. When I get to 1/40th second shutter speed the zebra stripes vanish, letting me know that the exposure is now perfectly exposed. Basically, any modern (or old film camera) assumes everything it sees is a mid tone 18 percent grey but white is a lot brighter than this so the camera will try and make it 18 percent grey by underexposing - by 1.7 stops in this instance. This is why if you are photographing white Polar Bears in the white snow for example you should work in full manual mode and overexpose by between 1.5 and 2 stops to compensate for this, otherwise the camera's metering system will try and make the snow grey, hence underexposing by 1.7 stops. So in this video when the Sony camera shows that it is overexposed by 1.7 stops when trained on the white card, the zebra stripes and my turning the shutter speed up in one third increments until they disappear, prove that the white card is, in fact, correctly exposed. It's worth noting that I had the camera's meter set to Multi Pattern metering, taking into account the entire scene. On Nikon's this is called Matrix metering and on Canon's it's called Evaluative metering. In these modes the meter is getting all that light off the snow and taking all that into account. Using spot metering on the actual subject will certainly help when shooting subjects in the snow, unless that subject is a white Polar Bear of course. I hope that makes things a little clearer.

[@smallbizdigitalmedia]

Great video. Not really sure though why you would bother with your white side zebra trick when you can just use the grey side without the workaround. That’s a great tip about using the card as a reflector :)

[@tecraven]

Thanks!

[@DovidSal]

some time has passed since the video was published. I kind of understand that this is for portrait photography. Where the subject is closer and you can set the grey card next to it or just in front of it. So, How to apply this technique on a different situation? Lets say a group of people or lets say street photography. Thank you

[@tecraven]

Hi David. Ok, same method. If it is outside for street photography, or better still, let's exaggerate, a landscape photo. If you are taking photos of the hills in the distance you don't have to walk 4 miles to get to them to hold a white or grey card up as the lighting a few miles away from the camera will be the same as it is a few feet away from the camera, we are not talking about taking a photograph with the camera in the UK and the subject in Australia where it would be night when it is day in England ;) Wild exaggeration, but I hope you see my point. You don't have to walk over to a group of people outside, just hold the grey or white card up a few feet from the camera as the lighting will be the same and this will always be more accurate than using the camera's metering system, which uses a best guess estimate on the assumption that the scene is 18 percent grey, which is typically never is, quite often not even close. But, worth remembering if you shoot RAW (which you should be) then you can pull the exposure right back and forth so even if the exposure is a few stops out in RAW it makes little difference so don't worry too much.

[@DovidSal]

@@tecraven excellent answer with a great sense of humor, congratulations for that too. It does not bother me at all the exageration; thank you so muich for sharing your experience and knowledge. Regards from FL USA. David

[@tecraven]

@@DovidSal No worries, David. Love Florida, nice holiday there once!

[@ahmedyadam7240]

How to use it with strobe lights

[@roeljanssen1470]

Great presentation, but how come you are using the gray card for white balance and the white card for exposure? Normal practice is to use the white card for white balance and gray card for properly exposing a scene. You even explain in the beginning of the video that 18% gray is a perfect midpoint between bright and dark areas!

[@tecraven]

Hi Roel, I’m not, I can see how on just one viewing of this video while downing your third glass of whine of the evening and not paying full attention that it might seem that way ;) But I’m using the guy card for exposure and the white for white balance. I do show how to take a white balance reading using the grey side as many folk do this, but at 2:54 in I then show how to take a white balance reading using the white side of the card. At 3:29 I adjust the exposure using the white side, but only because you have to set the exposure first before you can carry out a perfect white balance reading - if that makes sense? If there are zebra stripes (as per my explanation) and the image of the white card is over-exposed, it can affect the white balance and give you a false reading. For the record, strange as it might sound, you can still do a white balance reading with the grey side, which is why I demo that also, but I use the white side for white balance readings and the grey side for exposure. At 4:03 in I demonstrate taking a white balance reading with an over-exposed card and the reading is different, 4400k and not 4500k - it’s off due to overexposure. It means you just have to have perfect exposure on the white card when taking a white balance reading. I know my explanations are a bit technical, but watch it again a few times and you’ll get it.

[@bulletbling]

@@tecraven The only thing I didn't recall hearing (I could be wrong) is why +1.7 on the white side for white balance is the perfect exposure. I know it's because white is going to require a higher exposure setting to be true to life, but why +1.7? And would a 0.0ev cause it to be inaccurate?

[@tecraven]

@@bulletbling What part of the video, how many minutes and seconds it?

[@bulletbling]

It's at 6:06. Let me clarify because I can see my comment being misinterpreted from my intent...my comment wasn't supposed to suggest that exactly +1.7 is the exposure to use for white balance. That just so happened to be what you used...but why do you have it set to the highest exposure with no zebras? Is it more of an ETTR technique for the most data available to the camera so that the white balance is more precise?

[@tecraven]

@@bulletbling Austin, you're right, I should have explained this during the video. Basically, yes, the grey card is to achieve the correct exposure i.e. the meter at the bottom of the screen on the Sony A7 III camera would read 0.0, which is the case when I use the grey side of the card, as you can see in the video. However, the reason the exposure is reading +1.7 on the Sony screen when I'm using the white side is because the camera's metering system is assuming that the white side is in fact 18 percent grey, which I explain in the video, and, thus, this is how all camera exposure metering systems work. Now, although it is showing as +1.7 it is in fact perfectly exposed as I have the zebra stripes on the Sony set to 100, which means anything over 255 (RGB brightness levels go from 0 to 255 with 0 being black and 255 being white) will show up as zebra stripes, alerting the camera operator to the fact that these parts of the scene are overexposed. In the video I turn the shutter speed dial on the back of the camera and increase the shutter speed in one third increments from 1/25th, 1/30th, 1/40th. When I get to 1/40th second shutter speed the zebra stripes vanish, letting me know that the exposure is now perfectly exposed. Basically, any modern (or old film camera) assumes everything it sees is a mid tone 18 percent grey but white is a lot brighter than this so the camera will try and make it 18 percent grey by underexposing - by 1.7 stops in this instance. This is why if you are photographing white Polar Bears in the white snow for example you should work in full manual mode and overexpose by between 1.5 and 2 stops to compensate for this, otherwise the camera's metering system will try and make the snow grey, hence underexposing by 1.7 stops. So in this video when the Sony camera shows that it is overexposed by 1.7 stops when trained on the white card, the zebra stripes and my turning the shutter speed up in one third increments until they disappear, prove that the white card is, in fact, correctly exposed. It's worth noting that I had the camera's meter set to Multi Pattern metering, taking into account the entire scene. On Nikon's this is called Matrix metering and on Canon's it's called Evaluative metering. In these modes the meter is getting all that light off the snow and taking all that into account. Using spot metering on the actual subject will certainly help when shooting subjects in the snow, unless that subject is a white Polar Bear of course. I hope that makes things a little clearer.

[@fidodido664]

Does the white target on the grey card affect the metering?

[@tecraven]

Not at all. Too insignificant.