Gray Card for Exposure Help

DonaldC1961

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Hi Folks,

I would like to know who makes the most accurate gray card for exposure purposes for film and digital photography. I have purchased a couple different gray cards, neither of them being a Kodak R-27 gray card and there seems to be a discrepancy in tones. For example, I have an 8x10" gray card and a zone system value finder card. When I take the zone system value finder and place it on top of the gray card, the Gray card matches zone 3 on the zone system value finder, instead of zone 5, which is what I would expect it to be, all things being equal.

Am I missing something? It seems to me that my gray card and the zone system value card should match in zone 5, not 3, so either one of these tools is wrong, or I don't fully understand the zone system. If that is the case, would someone kindly help straighten me out?

Is the Kodak R-27 Gray card set a reliable purchase?

Thank you very much for your consideration,

Don
 

weepete

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From what I remember grey cards can be 12% or 18% grey could be this is what you are seeing, but that's quite a large difference. There's products like the colour checker passport, which have a bit more to them than grey cards are available to help colour accuracy.

Ultimatley exposure is a value judgement anyway, and there isn't an absolute value that means exposure is "correct". A colour accurate, calibrated monitor, a little help from a histogram and a good eye in post goes a long way to getting good exposure and is often enough unless you really need very accurate colour.
 

Douglas Brown

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Last grey card I purchased was two months ago from B&H. It was made by Delta Photography Supplies and seems accurate enough for my work. If you want a smaller version, and perhaps more accurate (?) maybe check X-Rite Color Checker.
 

snowbear

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Remember the % is related to reflectivity, not color or value (light/dark)
 

DarkShadow

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The Grey Card I got for free came with a Lens Calibration tool is useless, the white balance was not even close to be accurate.no wonder why it was free.
 
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DonaldC1961

DonaldC1961

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The Grey Card I got for free came with a Lens Calibration tool is useless, the white balance was not even close to be accurate.no wonder why it was free.

Did that happen to be the WhiBal lens calibration tool, or a knock off?
 

DarkShadow

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smoke665

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would like to know who makes the most accurate gray card for exposure purposes for film and digital photography.

"Accurate" as to what? Your asking for an absolute where there's a host of variables. Camera body, lens, film, scanners and monitors will all cause variances, as will not filling the frame. Whether you use 18%, 12% or a white sheet isn't as important as knowing where your peak should be on the histogram with a particular camera/lens/film or digital. IE: with an 18% gray I would expect it to fall somewhere between 95-120.
 
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DonaldC1961

DonaldC1961

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This one here but
The Grey Card I got for free came with a Lens Calibration tool is useless, the white balance was not even close to be accurate.no wonder why it was free.

Did that happen to be the WhiBal lens calibration tool, or a knock off?

This one here but I only wanted the Calibration tool so not a big deal.Vello LENS-2020 Lens Calibration Tool

I have not used this tool on my DSLR and lenses. How well has it worked for you?

Thanks,

Don
 
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DonaldC1961

DonaldC1961

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would like to know who makes the most accurate gray card for exposure purposes for film and digital photography.

"Accurate" as to what? Your asking for an absolute where there's a host of variables. Camera body, lens, film, scanners and monitors will all cause variances, as will not filling the frame. Whether you use 18%, 12% or a white sheet isn't as important as knowing where your peak should be on the histogram with a particular camera/lens/film or digital. IE: with an 18% gray I would expect it to fall somewhere between 95-120.

Hi Smoke665,
You pose a great question regarding "accurate as to what?" In a sea of variables, I see your point and that makes sense, especially in digital photography. My techniques vary from ETTR for certain situations, to using my light meter, which is calibrated to my cameras. From there, I can decide where I want to place my exposure with the scene I want to capture.

I am getting back into film photography via medium format, and trying to really dig in learning B&W, which includes learning and incorporating the Zone system. So my answer to your question has to do with my confusion as to why a gray card isn't necessarily congruent with zone 5 in the zone system. I am missing something in my understanding of the two products. Perhaps it is as simple as they serve two different purposes and I am over thinking this subject, or a gray card, used as a basis for exposure (a starting point), has nothing to do with where zone 5 lays in the zone system or the zone system at all. The other answer is the KISS method and trust my light meter in all situations.

I do appreciate your input.

Don
 

DarkShadow

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This one here but
The Grey Card I got for free came with a Lens Calibration tool is useless, the white balance was not even close to be accurate.no wonder why it was free.

Did that happen to be the WhiBal lens calibration tool, or a knock off?

This one here but I only wanted the Calibration tool so not a big deal.Vello LENS-2020 Lens Calibration Tool

I have not used this tool on my DSLR and lenses. How well has it worked for you?

Thanks,

Don
It did what it suppose to do, I only used it twice for the 50mm 1.8 prime. once on the Nikon Crop body that needed calibration and once on the D610 full frame that seems to be spot on with no adjustments needed.. I love this when a lens appears to be already married to the camera match made in heaven.
 

Ysarex

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White Styrofoam coffee cup works great. They're as accurate (or more so) than anything you can purchase and you get to drink the coffee. I just cut rectangles out of Styrofoam food trays and stick them in all my camera bags and jacket pockets etc. It doesn't have to be grey it only has to be repeatable.
 

smoke665

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I am missing something in my understanding of the two products. Perhaps it is as simple as they serve two different purposes and I am over thinking this subject,

I'm not sure it even matters. As Joe said above "it doesn't have to be gray only has to be repeatable". I'm no expert, just know enough to make me dangerous. I tend to rely more on histogram with digital, but in the old days with film it was meter and go.

Whether your card is 12% or 18% isn't as important as not swapping back and forth. I did find this which might give you some insight on what to expect on your histogram with an 18% or 12%. Using this formula (x^(1/MG))*256, where x=the percentage and MG=your monitor gamma. It should give you a theoretical peak on the histogram, but with the other variables it isn't going to be an exact science.

As to film, if you convert to digital, you're limited to 256 tones of gray in the RGB color model, with middle 18% gray being defined as equal shades of Red, Green and Blue(118,118,118), but in sRGB it's (128,128,128). So the exactness you seek is an elusive idea.
 
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