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- Thread starter derrycity
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- Mike Whitehouse
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Hi Derrycity 
I've got 2 gismos in my camera bag & I find them most useful.
1. WhiBal Card - www.whibal.com
2. ExpoDisc - www.expoimaging.net/products/produc...poDisc_Digital_White_Balance_Filter_-_Neutral
Have a look at thier web sites & see what you think...
I've got 2 gismos in my camera bag & I find them most useful.
1. WhiBal Card - www.whibal.com
2. ExpoDisc - www.expoimaging.net/products/produc...poDisc_Digital_White_Balance_Filter_-_Neutral
Have a look at thier web sites & see what you think...
I don't see how you can't use one, take a grey card shot, set custom white balance and for get about it (assuming conditions don't change) I also use a whibal card and Expodisc, I tend to use the expodisc most of the time.
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I think it's far LESS hassle to get it right at capture than try to sort it out later in a series of similar shots (i.e. a wedding), though it is less important to a nice landscape for example
Expodisc for me -
DD
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- Darren
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Dont forget that 18% for metering and neutral grey for WB are totally different things.
I'm not sure that the bag lining could be all that great for colour reference.
Also, I've never looked at the expodisk before, isn't that a clever little gizmo. Sod all use for the way that leaf software works, so I'll stick with the card but what a great idea.
I'm not sure that the bag lining could be all that great for colour reference.
Also, I've never looked at the expodisk before, isn't that a clever little gizmo. Sod all use for the way that leaf software works, so I'll stick with the card but what a great idea.
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I have a fold out Latolite grey target that I use in a controlled environment (studio). It makes life so much easier, as you don't have to guess what the white ballance should be. Set it on one, replicate to all images in lightroom.
I also have a Pringles lid (the opaque ones before they went clear) and it actually gives you the same result as using an expo disk, without spending the money. If I am shooting an indoor sport, or in a mixed lighting environment, I just hold it over the end of the lens, take my shot, and set the WB.
I also have a Pringles lid (the opaque ones before they went clear) and it actually gives you the same result as using an expo disk, without spending the money. If I am shooting an indoor sport, or in a mixed lighting environment, I just hold it over the end of the lens, take my shot, and set the WB.
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- Denyer
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Semi opaque pringles lids (if you can still find them) work great. Also Lee Filters sell semi-opaque white caps for use when you have the filter holder mounted but can't fit your lens cap. They're about £3 for 3 if I recall, and make similarly excellent shoot-through whitebalancers.
Voila: http://www.speedgraphic.co.uk/prod.asp?i=12222&1=Lee+Adaptor+Ring+Caps+(3)
(Also useful if you happen to use Lee filters a lot!)
Voila: http://www.speedgraphic.co.uk/prod.asp?i=12222&1=Lee+Adaptor+Ring+Caps+(3)
(Also useful if you happen to use Lee filters a lot!)
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- Tim
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You don't need a grey card in order to accurately gauge an exposure reading....
Here are four photos, taken two seconds apart, effectively under the same lighting conditions. I spot metered in Av mode with +0 EC for each. Aperture was kept at f/11 for each shot and ISO at 400. The shutter speed has been automatically altered depending on the reflectivity of the object in the centre of the frame.
1. Lowepro grey cloth - metered reading = 1/1000. We'll assume this sets the baseline for a "correct" exposure in this lighting.
2. Sheet of white A4 paper - metered reading = 1/3200. That means the light reflected was 1 2/3 stops brighter than the grey reference.
3. Grass - metered reading = 1/400. That means the light reflected was 1 1/3 stops dimmer than the grey reference.
4. My palm - metered reading = 1/2500. That means the light reflected was 1 1/3 stops brighter than the grey reference.
5. Following the sunny 16 rule, at f/11 and 400 ISO my shutter speed should have been 1/800. That's just 1/3 stop brighter than the grey card, which, as the sky had a hint of whispy cloud in front of the sun seems bang on.
So what does this all mean? Well, if you assume the Lowepro grey cloth makes a good grey card (which it appears to) then you could equally well....
- meter off a sheet of white paper and set the exposure to +1 2/3 over;
- meter off some "typical" grass and set the exposure to - 1 1/3 stops under;
- meter off the palm of *my* hand (yours will likely be pretty similar, if caucasian) and set the exposure to +1 1/3 stop over the meter.
Sheets of paper are very cheap and palms are free. So if you like, you can forget the grey card and just use your palm +1 to +1 1/3 stops to set your exposure. You use your palm because it does not tan and will thus remain constant and reliable throughout the year.
Setting white balance is, of course, an entirely different topic from exposure, but I get quite satisfactory results by shooting raw and setting WB from anything white or grey in one of the photos in the set. A white shirt is good, some paper or a sign, white ceiling etc.. Fine tuning is always possible from that point if you want to add a creative adjustment - and your monitor is calibrated /profiled correctly.
Here are four photos, taken two seconds apart, effectively under the same lighting conditions. I spot metered in Av mode with +0 EC for each. Aperture was kept at f/11 for each shot and ISO at 400. The shutter speed has been automatically altered depending on the reflectivity of the object in the centre of the frame.
1. Lowepro grey cloth - metered reading = 1/1000. We'll assume this sets the baseline for a "correct" exposure in this lighting.
2. Sheet of white A4 paper - metered reading = 1/3200. That means the light reflected was 1 2/3 stops brighter than the grey reference.
3. Grass - metered reading = 1/400. That means the light reflected was 1 1/3 stops dimmer than the grey reference.
4. My palm - metered reading = 1/2500. That means the light reflected was 1 1/3 stops brighter than the grey reference.
5. Following the sunny 16 rule, at f/11 and 400 ISO my shutter speed should have been 1/800. That's just 1/3 stop brighter than the grey card, which, as the sky had a hint of whispy cloud in front of the sun seems bang on.
So what does this all mean? Well, if you assume the Lowepro grey cloth makes a good grey card (which it appears to) then you could equally well....
- meter off a sheet of white paper and set the exposure to +1 2/3 over;
- meter off some "typical" grass and set the exposure to - 1 1/3 stops under;
- meter off the palm of *my* hand (yours will likely be pretty similar, if caucasian) and set the exposure to +1 1/3 stop over the meter.
Sheets of paper are very cheap and palms are free. So if you like, you can forget the grey card and just use your palm +1 to +1 1/3 stops to set your exposure. You use your palm because it does not tan and will thus remain constant and reliable throughout the year.
Setting white balance is, of course, an entirely different topic from exposure, but I get quite satisfactory results by shooting raw and setting WB from anything white or grey in one of the photos in the set. A white shirt is good, some paper or a sign, white ceiling etc.. Fine tuning is always possible from that point if you want to add a creative adjustment - and your monitor is calibrated /profiled correctly.
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with white paper though, the amount of bleaching will differ between products.
the palm of the hand seems to be the most reliable i think
the palm of the hand seems to be the most reliable i think
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- Tim
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True, but if you have *your* piece of white paper handy, rather than just any old scrap, then you can calibrate *your* metering in *your* camera to *your* bit of paper.
If you have a ream of A4 lying around for your printer then that should be pretty good for starters and if that gets lost/damaged then just grab another sheet when you get home.
Another approach to caibrating your sheet of paper is to set manual exposure and set an exposure so that the meter reading is at +1 and take a shot. Have a look at the histogram and see how much space you have remaining over on the right. There will probably be a good gap. Now increase the exposure by 1/3 stop and try again. How does the histogram look? Repeat until you get up to +2, or even a little more if you like.
I just took the same approach as described above, starting with a manual exposure at +1 and then incrementing by 1/3 stops up to +2. I was using spot metering so the centre of the paper wasthe only important thing for the meter. The bit of grass in the corner had no bearing on the meter reading. See how the histogram is nudging closer and closer towards the right of the histogram but even at +2 there is still a safe margin. In fact that last shot, at +2, is the only shot where the paper actually looks like a white sheet of paper, rather than murky grey.
Now, in DPP I took that last image, shot at +2, and gradually increased the exposure (raw brightness) until I saw signs of blown highlights. I was able to add exactly 1 full stop more to the exposure before I started to blow the highlights. That is a nice safe margin for retaining highlight detail in anything as bright/reflective as the piece of paper and even brighter still. With that exposure setting I should be pretty safe to capture details in the whitest wedding dress, or dress shirt, with no problems at all.
Here is a screen print of the +2 image with a further 1 stop of brightening in DPP. As you can see, the image has started to blow in some areas but it is not fully blown all over. In fairness I should really say that my safe margin in not quite 1 full stop, but rather 5/6 stop. Close enough though...
Here is how the histogram looks in Lightroom with no adjustments at all....
As you can see, I have a nice clear safety margin on the right of the histogram here too.
By the way, the exposure here at +2 was f/8, 1/1600, 200 ISO which is an exact match for the Sunny 16 rule - It is a sunny day today
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Thanks, Janice
This little experiment also demonstrates that for my camera/meter I have exactly 3 stops of exposure latitude above the centred metered reading. This coincides with modern day thinking that (digital) camera meters are now calibrated to work with a 12 or 13% grey card rather than an 18% grey card. In fact, if you think about it, to get 3 stops of headroom you want a 12.5% card. 1 stop over 12.5% = 25%. Another stop over 25% = 50%. One more stop over 50% = 100%, and you can't go higher than that with a digital sensor.
So, if you do want to buy a grey card, for a modern (digital) camera, make sure it is around 12-13% reflectivity and not 18%. An 18% grey card will reflect more light than a 12% card, so it appears brighter and you will get a lower exposure as a result. Thus you'll gain about 1/3 to 1/2 a stop of headroom but get a darker exposure at the same time. For digital cameras that is bad because your shots will appear underexposed and you'll risk adding noise if you try to brighten them. So basically you want a grey card with the same reflectance that your meter is calibrated for.
So really it's just as easy, and a good deal cheaper, to perform your own calibration, with white paper or your own palm.
p.s. Janice, if I may refer you back to this old thread - http://www.talkphotography.co.uk/forums/showthread.php?t=56721 - perhaps you will now have a better understanding of why I suggested metering off the very brightest part of the sky and setting the exposure to +3 stops for that meter reading. If you expose at +3 for the very brightest part of the scene then anything else in the scene must fall within the sensor's capture range. Nothing will be blown at all. Sorry I was a bit abrupt in post 13 of that thread.
This little experiment also demonstrates that for my camera/meter I have exactly 3 stops of exposure latitude above the centred metered reading. This coincides with modern day thinking that (digital) camera meters are now calibrated to work with a 12 or 13% grey card rather than an 18% grey card. In fact, if you think about it, to get 3 stops of headroom you want a 12.5% card. 1 stop over 12.5% = 25%. Another stop over 25% = 50%. One more stop over 50% = 100%, and you can't go higher than that with a digital sensor.
So, if you do want to buy a grey card, for a modern (digital) camera, make sure it is around 12-13% reflectivity and not 18%. An 18% grey card will reflect more light than a 12% card, so it appears brighter and you will get a lower exposure as a result. Thus you'll gain about 1/3 to 1/2 a stop of headroom but get a darker exposure at the same time. For digital cameras that is bad because your shots will appear underexposed and you'll risk adding noise if you try to brighten them. So basically you want a grey card with the same reflectance that your meter is calibrated for.
So really it's just as easy, and a good deal cheaper, to perform your own calibration, with white paper or your own palm.
p.s. Janice, if I may refer you back to this old thread - http://www.talkphotography.co.uk/forums/showthread.php?t=56721 - perhaps you will now have a better understanding of why I suggested metering off the very brightest part of the sky and setting the exposure to +3 stops for that meter reading. If you expose at +3 for the very brightest part of the scene then anything else in the scene must fall within the sensor's capture range. Nothing will be blown at all. Sorry I was a bit abrupt in post 13 of that thread.
KIPAX
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- Tim
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My calibration results above were with my 30D. I just tried the same calibration with my 40D and the same sheet of paper. I also used the same lens, ISO and aperture, varying only the shutter speed, as before.
This time I started out at +1 and took a series of seven photos, in 1/3 stop intervals, all the way up to +3 stops. Even at +3 stops there was no sign of anything blowing. In DPP I was able to add another 1/6 stop with no signs of clipping and only by adding 1/3 stop to the +3 exposure did I finally see clipping in some of the paper. So I have almost 3 1/3 stops of headroom with my 40D compared to the almost 3 stops of headroom that the 30D gives me in like for like conditions. This is what I said about my 40D in the other thread I referred to earlier.
By the way, the +2 stops exposure on the 40D gave me the same 1/1600 shutter speed that the 30D gave me. So even though the metering is identical, I have an extra 1/3 stop safety margin on the 40D compared to the 40D. I think that is because, according to comments I have read on the net, HERE and HERE, 100 ISO on the 30D is actually more like 125 ISO, whereas the 40D is accurately calibrated so that 100 ISO is a true 100 ISO. So the extra "hidden" sensitivity of the 30D can cause it to blow highlights earlier than the 40D. It should also give fractionally brighter images than the 40D when all settings are exactly identical.
What this does mean is that when using my 40D I could meter off the same sheet of white paper but would need to bump my compensation up to +2 1/3 stops for the 40D and only +2 stops for the 30D to achieve the exact same exposure in both cameras. It also shows that you should take the time to calibrate your own camera against your own test target.
Thinking about this further, it doesn't really matter whether you have a 12% grey card, 13% grey card, 18% grey card, a sheet of white paper, or your own palm. The important thing is that you know how much compensation to apply for your chosen exposure target, for your camera.
Finally, if you shoot raw and like to expose to the right, it is important to understand just how much extra headroom you do have above whatever you meter with. For example, let's say you are shooting a sports scene - perhaps kids playing baseball in the park. Consider whether there is anything (important) in the scene that would be brighter or more reflective than the paper. There might be white baseball caps, or shirts, and they would probably be about as bright/reflective as the paper - but what else could/would be brighter still? Maybe some shiny white paint on a car in the background (not very important and should be blurred out of interest by shallow DOF in any case), or reflective metalwork or glass, or maybe nothing. If the answer is "nothing" then instead of only going to, say, +2 stops above the metered reading for the paper you could perhaps go to +2 1/3, +2 2/3 or even +3 stops above the metered reading. You'll still hold the detail in the highlights but will have more raw data to play with and can fine tune shadow detail and/or bury noise if you are shooting at higher ISOs.
If, on the other hand, you are shooting motorsports and could have shiny paintwork, glass and metal as part of your subject, you will likely want to be very careful to preserve detail in those brighter areas, and could happily lose shadow detail under the car or in the wheel arches, for example. In this case you would probably want to play safe with a standard exposure rather than pushing the limits of the right hand edge of the histogram.
This time I started out at +1 and took a series of seven photos, in 1/3 stop intervals, all the way up to +3 stops. Even at +3 stops there was no sign of anything blowing. In DPP I was able to add another 1/6 stop with no signs of clipping and only by adding 1/3 stop to the +3 exposure did I finally see clipping in some of the paper. So I have almost 3 1/3 stops of headroom with my 40D compared to the almost 3 stops of headroom that the 30D gives me in like for like conditions. This is what I said about my 40D in the other thread I referred to earlier.
By the way, the +2 stops exposure on the 40D gave me the same 1/1600 shutter speed that the 30D gave me. So even though the metering is identical, I have an extra 1/3 stop safety margin on the 40D compared to the 40D. I think that is because, according to comments I have read on the net, HERE and HERE, 100 ISO on the 30D is actually more like 125 ISO, whereas the 40D is accurately calibrated so that 100 ISO is a true 100 ISO. So the extra "hidden" sensitivity of the 30D can cause it to blow highlights earlier than the 40D. It should also give fractionally brighter images than the 40D when all settings are exactly identical.
What this does mean is that when using my 40D I could meter off the same sheet of white paper but would need to bump my compensation up to +2 1/3 stops for the 40D and only +2 stops for the 30D to achieve the exact same exposure in both cameras. It also shows that you should take the time to calibrate your own camera against your own test target.
Thinking about this further, it doesn't really matter whether you have a 12% grey card, 13% grey card, 18% grey card, a sheet of white paper, or your own palm. The important thing is that you know how much compensation to apply for your chosen exposure target, for your camera.
Finally, if you shoot raw and like to expose to the right, it is important to understand just how much extra headroom you do have above whatever you meter with. For example, let's say you are shooting a sports scene - perhaps kids playing baseball in the park. Consider whether there is anything (important) in the scene that would be brighter or more reflective than the paper. There might be white baseball caps, or shirts, and they would probably be about as bright/reflective as the paper - but what else could/would be brighter still? Maybe some shiny white paint on a car in the background (not very important and should be blurred out of interest by shallow DOF in any case), or reflective metalwork or glass, or maybe nothing. If the answer is "nothing" then instead of only going to, say, +2 stops above the metered reading for the paper you could perhaps go to +2 1/3, +2 2/3 or even +3 stops above the metered reading. You'll still hold the detail in the highlights but will have more raw data to play with and can fine tune shadow detail and/or bury noise if you are shooting at higher ISOs.
If, on the other hand, you are shooting motorsports and could have shiny paintwork, glass and metal as part of your subject, you will likely want to be very careful to preserve detail in those brighter areas, and could happily lose shadow detail under the car or in the wheel arches, for example. In this case you would probably want to play safe with a standard exposure rather than pushing the limits of the right hand edge of the histogram.
Messiah Khan
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Excellent writeup tdodd. Very helpfull indeed.
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I just checked my Kodak 18% Grey Card and it's considerably darker,you can see this at a glance, I checked it with a Gossen Digipro F Light meter and it's one stop darker exactly.