What Gray Card?

jeffreyg · May 6, 2023

Alan,
all my readings were at the same angle.

Drew,
I have used my gray cards and light meters including an incident meter for many years and I suppose that although they may not be critically accurate it has worked perhaps by printing. I do black and white and print in my home darkroom in silver-gelatin, platinum/palladium and from scanned negatives. Color is digital family snapshots with the camera doing the thinking. The Home Depot remarks were in response to someone looking for a cheap gray card. I was in Home Depot and noticed the gray swatches and wondered what if?

http://www.jeffreyglasser.com/

http://www.sculptureandphotography.com/

DREW WILEY · May 6, 2023

Well, yeah, black and white printing involves a continuous gray scale and allows you get away with quite a few things you might get a jaywalking ticket for when using color neg film, or a felony warrant if shooting color chrome film. But even with a digital camera, don't you need sometimes to gray and white balance it against a standard? And some of those balancing discs are more accurate today than most official gray cards are. Might as well use em for both kinds of photography. Trying to read a tiny little paint chip is pretty hard with any meter.

jeffreyg · May 6, 2023

I don't use the paint chips. I use acrylic gray cards that I got years ago. Most of the time I don't use a gray card but my version of a zone system. It works well for me. I go by "if it ain't broke, don't fix it". I do photography for me and those who wish me to share. It isn't my profession although I have been pleasantly accepted.

Roger Cole · May 6, 2023

runswithsizzers said:
Thank you. I do have a couple of light meters, and in tricky lighting situations, the first thing I do is to take an incident reading. And I am also painfully aware of how the "shine" from the surface of a gray card can affect meter readings.

The great minds of the forum will no doubt think it irrelevant - and possibly a Bad Idea - but my thought was to include a gray card in some of my photos to see if it might be helpful in evaluating exposure and white balance AFTER the scene is metered and captured. Yes? No?

It's useful for color printing. When I used to do RA4 printing if I were going to take several photos in the same lighting, particularly if it had some color cast, and had time, I'd take a photo of the gray card in that lighting. Color balance for that to match the card I had right in hand to compare, and the filter pack is good (or very very close - you might want to nudge it "off" a bit for the subject but...) for that lighting at that time.

RalphLambrecht · May 7, 2023

runswithsizzers said:
Thank you. I do have a couple of light meters, and in tricky lighting situations, the first thing I do is to take an incident reading. And I am also painfully aware of how the "shine" from the surface of a gray card can affect meter readings.

The great minds of the forum will no doubt think it irrelevant - and possibly a Bad Idea - but my thought was to include a gray card in some of my photos to see if it might be helpful in evaluating exposure and white balance AFTER the scene is metered and captured. Yes? No?

Yes, that will be helpful when printing.

wiltw · May 8, 2023

jeffreyg said:
I happened to be in Home Depot and selected twelve swatches that looked like they would be close to my existing gray cards. All were Behr Dynasty Marquee line: dawn gray, imperial gray, dawn, gray, imperial gray, antique tin, ocean swell, euro gray, lengandry gray, and the Ancestral ppi-24-05. I was just doing this out of curiosity to see if any matched the gray cards I have been using for years I thought reading with spot meters under constant illumination at the same angle would be interesting and see if my light meters agreed with each other. And since the original post was looking for a cheap gray card it might be an answer. You might want to do it more scientifically and give us all a better answer

OK, went to Home Depot and found all of the colors, with exception of 'dawn' or 'gray'. Arranged them on a piece of foam core, and photographed them collectively along with a genuine Kodak gray card, under cloudy overcast.

I measured the Kodak gray card as the basis for exposure, then used the Minolta Spotmeter F to see how much tonality deviation from the Kodak card, to determine amount of exposure error if that card was the basis of exposure (rather than the Kodak card).
An error of -0.5EV means the card is darker than Kodak 18% gray card, and using that as basis of exposure would result in +0.5EV overexposed shot.
I used Lightroom to balance Kodak card to absolute neutral (due to the cool lighting for the photo, which resulted in setting of 5700K as 'neutral'), and the Kodak also served as the Color Temp control patch.
Then I used each of the Behr cards to determine the Kelvin temp needed to render that card neutral, and recorded the values.

Here are the results of the Behr color samples as surrogates, with deviations shown from the Kodak control patch

Top row
Ancestral: -0.5EV, +150K cool
Antique Tin: -0.7EV, +800K cool
Dawn gray: -0.6EV, +750K cool

Ocean swell: -0.8EV, +1100K cool

Bottom row
Euro gray: -0.1EV, +550K cool
Imperial gray: -0.9EV, +650K cool
Legendary gray: -0.4EV, +850K cool

The best surrogate for exposure was Euro Gray, the best surrogate for neutrality was Ancestral.
Here I show correct WB (1), +150K too cool inducing slight warmth (2) and +1100K too cool inducing considerable warmth (3) caused by choice of the wrong color sample paint choice.

tomkatf · May 8, 2023

Interesting to render your photo into grayscale, removing the color tints...(which may or may not be helpful)...

Bill Burk · May 8, 2023

Ok so Ancestral, buy a quart and add white to it!

wiltw · May 8, 2023

tomkatf said:
Interesting to render your photo into grayscale, removing the color tints...(which may or may not be helpful)...

View attachment 338132

It is quite interesting when color saturation reduction resolves it all to neutral tonality, the color patch which best matches the Kodak gray card tonality is the Ocean Swell sample, which induces 0.8EV error in metering!

tomkatf · May 8, 2023

wiltw said:
It is quite interesting when color saturation reduction resolves it all to neutral tonality, the color patch which best matches the Kodak gray card tonality is the Ocean Swell sample, which induces 0.8EV error in metering!

A further step down the rabbit hole would be to get a Zone VI modified meter and take readings of your samples and compare results......

wiltw · May 8, 2023

tomkatf said:
A further step down the rabbit hole would be to get a Zone VI modified meter and take readings of your samples and compare results......

Thank you, I'll pass! My understanding of the filtration to balance meter sensitivity to different colors should not really provide much difference on supposedly neutral gray cards.
And, besides, I do not think Zone VI modifications by Picker were ever done to a Minolta Spotmeter. Someone owning a Zone Vi modified meter is invited to make suitable tests and report back!

Sirius Glass · May 8, 2023

Why so much fuss and bother when one can get light meters calibrated by light meter specialists. I have had all my light meters calibrated and I do not need no stinkin' gray card.

jeffreyg · May 8, 2023

Thanks Welt. Interesting results. Actually I used two Zone VI Pentax Digital Spotmeters when I did the test

bjorke · May 8, 2023

Sirius Glass said:
Why so much fuss and bother when one can get light meters calibrated by light meter specialists. I have had all my light meters calibrated and I do not need no stinkin' gray card.

...until you're shooting video with two cameras and on-set practical monitors and open sky and need to intercut the footage

DREW WILEY · May 8, 2023

Bill - there is no such thing as true white in a paint store, much less in an outlet like Cheapo Depot. Nor is there ever a true black. Tint or tone, and you get a hue change with it too, and not gray neutrality. Wilt's experiment reinforces my own statements : there's a wacky amount of variation in all of this unless you are using a high-quality reference like the MacBeth chart itself. The swing from yellow-brownish-gray to bluish-gray in those alleged "gray"cards is certainly the kind of variance significant enough to mess up a fussy chrome film exposure.

There's plenty of old chatter on Picker's modified meters. Some of these have been used in relation to even color neg filming in Hollywood, though regular unmodified Pentax spotmeters are dominant. The whole native flaw in the Picker idea is that all panchromatic films are the same in terms of spectral sensitivity, which they're not! What was his standard - Tri-X perhaps? Then those supplementary filters he placed in them fade over time, and need to be replaced. And all those modified ones are pretty old by now.

wiltw · May 8, 2023

Sirius Glass said:
Why so much fuss and bother when one can get light meters calibrated by light meter specialists. I have had all my light meters calibrated and I do not need no stinkin' gray card.

You obviously never shoot brides dressed in white wedding gowns, nor grooms in black tuxes, either one solo in shots. Nor shoot snow scenes. Nor ever have color reproduction fussy clients. Lucky fella.

DREW WILEY · May 8, 2023

Try printing those extremes on Cibachrome afterwards, based on chrome film exposures. I not only did it, but routinely did it well. No precise metering? = no payday. No wiggle room for error. No, I didn't use gray cards, but did know what values to compare using a spotmeter in relation to middle gray, based on experience. But any new film unfamiliar to me - that's when I always tested things in advance, using the MacBeth chart and a validated gray card under strict standardized conditions.

Sirius Glass · May 8, 2023

wiltw said:
You obviously never shoot brides dressed in white wedding gowns, nor grooms in black tuxes, either one solo in shots. Nor shoot snow scenes. Nor ever have color reproduction fussy clients. Lucky fella.

All of that has never been a problem because an incident meter solves those problems easily and well.

Breadbutter · May 8, 2023

Just in case someone is still looking for gray cards. Freestyle Photographic Supplies has 18% Delta gray cards in stock.

DREW WILEY · May 8, 2023

Sirius - Was that just incidental luck?

Breadbuttger - Delta cards, actually plastic, are all over the map one to another, depending on specific batch. So so at best.

Bill Burk · May 8, 2023

DREW WILEY said:
Bill - there is no such thing as true white in a paint store, much less in an outlet like Cheapo Depot. Nor is there ever a true black. Tint or tone, and you get a hue change with it too, and not gray neutrality. Wilt's experiment reinforces my own statements : there's a wacky amount of variation in all of this unless you are using a high-quality reference like the MacBeth chart itself. The swing from yellow-brownish-gray to bluish-gray in those alleged "gray"cards is certainly the kind of variance significant enough to mess up a fussy chrome film exposure.

There's plenty of old chatter on Picker's modified meters. Some of these have been used in relation to even color neg filming in Hollywood, though regular unmodified Pentax spotmeters are dominant. The whole native flaw in the Picker idea is that all panchromatic films are the same in terms of spectral sensitivity, which they're not! What was his standard - Tri-X perhaps? Then those supplementary filters he placed in them fade over time, and need to be replaced. And all those modified ones are pretty old by now.

Yup his standard was Tri-X you can read about it in his Zone VI newsletters. Sure a showman.

I suppose I could tell the guy at the hardware store to give me the colorants separately from the base. I could paint a bit, let it dry and check it with a seven channel spectrophotometer. If it can fool that it’s probably good enough for me.

Breadbutter · May 8, 2023

DREW WILEY said:
Sirius - Was that just incidental luck?

Breadbuttger - Delta cards, actually plastic, are all over the map one to another, depending on specific batch. So so at best.

Good to know.

wiltw · May 8, 2023

Sirius Glass said:
All of that has never been a problem because an incident meter solves those problems easily and well.

I'm actually with you...my ownership of gray cards is less to do with metering, per se, mostly as a standardized TARGET for reproduction accuracy of both tonaity and neutrality. What I use as 'targets'... after using incident meter for exposure.

Color reproduction accuracy

Tonality and contrast reproduction

DREW WILEY · May 9, 2023

Those tools are what everyone should own, Wilt. Way more useful than so-so quality gray cards.

Thomas71 · May 13, 2023

Sirius Glass said:
All of that has never been a problem because an incident meter solves those problems easily and well.

Here in Italy a well-known b&w teacher states that incidental reading leads to systematic underexposure and that the greater the contrast in the scene, the greater the level of underexposure. I honestly have not yet understood the reasons for this and use incidental reading when I can.

What Gray Card?

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