What Gray Card?

[wiltw]

It seems to be a gray area for some.

<groan>

 

[wiltw]

If it can't be guaranteed as a match then I'd have thought that given the ability of the human eye to detect even a small difference in shades ( see my Dulux analogy above ) then if we assume that there might be a small difference in eye detection as opposed to an expensive machine detection can I ask how much difference is this likely to make to an exposure reading

Not enough to matter, less than 0.1EV. But 18% gray is also used as a reproducible 'neutral' standard to assure better reproduction of color hues, and some kinds of clients are extremely picky about color portrayal of their product in ads. So a very slightly 'cool' gray vs a very slightly 'warm' gray as the control color in the photo rather than absolutely 'neutral' can throw off color reproduction of the actual subject.

 

[DREW WILEY]

Well, yes, just like gray cards, gray matter itself is prone to fading and going mildewed or warped, or forgetting even what that means.

And for those with even less math intelligence than me, I already stated way back that some of the gray cards I measured were at 15% off or worse. Then given the variable of reflectance, and you could be off two whole stops! That ain't chump change. Even half a stop off would be a killer with chrome film. As far as paint goes, it's the difference between the painter making tens of thousands of dollars on some fancy Victorian redo, or getting fired and sued for tens of thousands! We ain't talkin' 'bout tract homes and college dropout painters straying mud on the walls. Right now, premium house paints are approaching a hundred dollars a gallon. But they're often the best value over time - need less coats way less often; and labor is always a much higher factor anyway.

Just wade your way through the mobs of tourists there on Steiner St, Wilt. Not only did I supply gosh knows how many hundreds of thousands of dollars of goo-gaw shiny hardware to those places (the mere thought of polished brass makes me sick at this point); but dig up a copy of Morley Baer's famous book, Painted Lady's, when the color restoration trend began. Back then I was selling high-end industrial enamels at $75 per gallon, way back in the early 70's, to hippies who could barely afford food, but wanted the most psychedelic colored Victorian on the block.

Then later I consulted in relation to the restoration of Janis Joplin's mansion - it's like walking inside Salvador Dali's brain. Weird, weird, weird; and expensive, expensive, expensive - colors had to be spot on, even if diabolical. True gold leaf, black, pink, and purple, along with 16 ft high true stained glass windows salvaged from a cathedral. The new owners wanted to turn it into a Graceland kind of venue; but the locals knew what kind of person she really was, and that stopped those plans right in their tracks. Lots of skeletons in those closets. Sad, really. But it was an interesting restoration challenge, of which I was just one of numerous contributors. Worked with lots of Julia Morgan restorations, Bernard Maybeck ones, at least one Frank Lloyd Wright. Stumbled into one of my former clients last week, who I also did photography for.

 

[Pieter12]

Not enough to matter, less than 0.1EV. But 18% gray is also used as a reproducible 'neutral' standard to assure better reproduction of color hues, and some kinds of clients are extremely picky about color portrayal of their product in ads.

That is why a serious client and agency will spend the big bucks and have a specialist make color-corrected hero packaging specifically to be photographed. Plus, there is always a significant amount of color correction that goes into post-production.

 

[pentaxuser]

Thanks Drew, I feel as if I now have more insights into your colourful life than I have the right to know. Sounds like you could have called yourself the "Eminence Grise" of N. Cal That apart, I'll take it that the breakfast cereal grey card is not such a bad idea as you seemed to suggest in an earlier post. I do hope that the poster was not offended by your reply. It did seem to pour more scorn onto his post than you may have meant

Sounds as if the grey card granite and grey card asphalt aren't bad either. Mmm.... $100 per hour in the 80s and there were only two of you for whole of NCal - well three but one sounds crap. | By today's value that's about $350 an hour so with only 2 of you that's probably as many hours work per week as you cared to devote so say $1400 per week minimum. Wow!

Your real name isn't Musk is it?

pentaxuser

 

[DREW WILEY]

Much of our Sierra granite is consistently gray salt and pepperish; and it's stable and fade resistant; and if you put a sizable chunk of that kind of gray card in your pack, there's no way you're going to lose it, because you sure as heck can't walk anywhere! But I've actually accidentally dunked my meter in icy mountain streams twice, and had to base all my exposures, even chromes, on sheer memory based on lots of previous experience, and even the chromes came out perfectly. Not that I recommend that. The meter involved worked fine after drying out. Now I keep them much more carefully tethered.

Publishers could be very picky about correct chrome exposure. They used light boxes and preferred easily readable 4x5 originals without excessive contrast, and certainly no serious exposure errors, since the color separation process was somewhat lossy. It not like magazines, even the fancy glossy ones, could afford a lot of extra time and fuss. Of course, scanners changed that somewhat; but the original still needs to be reasonably in bounds. But they sure don't pay like they used to.

 

[takilmaboxer]

The palm of my hand always reads Zone VI

 

[Bill Burk]

@DREW WILEY

Tell me about the pigment and base you used for that quart of paint.

I once wanted to paint a gray backdrop so I got quart(s) of white and told the guys at Ace to put the pigment for black in a jar.

Then I took a bunch of beer pong cups and made a variety of shades from dark gray to faint gray.

The damn thing turned out green like camouflage. Not the look I was going for at all. The next time I was more careful and got a better shade, but the tint wanders around from bluish-green to gray. Almost like when you put in too much Potassium Bromide in the Dektol.

But seriously the best gray card out there is the Sekonic. Maybe you can check one out, Drew but what makes it unique is the small patches that make up a full stop of range in 1/6 stop increments. So when you read a result, you can see which chip gave the closest to expected results and can adjust your calibration accordingly to 1/6 stop accuracy.

 

[wiltw]

Publishers could be very picky about correct chrome exposure. They used light boxes and preferred easily readable 4x5 originals without excessive contrast, and certainly no serious exposure errors, since the color separation process was somewhat lossy. It not like magazines, even the fancy glossy ones, could afford a lot of extra time and fuss. Of course, scanners changed that somewhat; but the original still needs to be reasonably in bounds. But they sure don't pay like they used to.

One of the reasons for 'pickiness' is simply the fact that offset press reproduction of photos is more limted in its dynamic range than even transparency photos! Perhaps a 4 stop tonal range (amount actually dependent on the dot matrix 'screen' density). I would rountinely measure the dynamic range of the scene and adjust lighting to all fit within the narrower dynamic range, although the color transparency could support a wider range.

 

[DREW WILEY]

Hi Bill - sorry, but what you request cannot be given a simple explanation, especially since the specific product as well as the pigments involved have all changed multiple times, about once a decade in fact. But at the heart of the problem is that there is no such thing as a true black paint pigment. It just looks black if concentrated enough. Mineral blacks have a greenish bias, and lampblacks, purplish. That is quite evident when toning them in white to achieve gray. Ace paint was made by Valspar, and used typical cheap pigments; so your frustration would have been predictable.

It takes an offsetting with other pigments to achieve neutrality. But at the time, Benjamin Moore offered me big master sets of color samples, printed far more accurately than ordinary paint chips available to the public, along with full tables of reflectance value for every single color. Yet even that wasn't sufficient for a gray standard which I wanted to read neutral 18% gray not only clear across the visible spectrum, but a step beyond in both directions, slightly into UV and IR. Overkill, sure - but I was itchy to find out if it could be done, mainly just for fun. And I had access to a serious spectrophotometer capable of measuring that. Another issue is that paint chips, in whatever quality grade (the store ones are always the cheapest), are still printing inks, and can never really represent precise pigment results. That's why serious painters always request samples of the real deal.

I don't know much about Sekonic products, except that I have a Sekonic lux meter which I once used to balance gallery lighting. Sekonic was not among the gray card brands I tested back then.

 

[DREW WILEY]

takilmaboxer - yeah, that ole Caucasian palm of hand thing - "It's alway one stop above 18%". Had an in-law of German descent who was a mailman in Las Vegas. His palm looked like two stops BELOW mid gray.

 

[Sirius Glass]

Use your hand which is usually attached and handy for the reading and then close down one stop.

The palm of my hand always reads Zone VI

​

 

[DREW WILEY]

What about the palm of local politicians, which are always greased green?

 

[Sirius Glass]

What about the palm of local politicians, which are always greased green?

They can be a slimy goop group.

 

[Nicholas Lindan]

But seriously the best gray card out there is the Sekonic ... what makes it unique is the small patches that make up a full stop of range in 1/6 stop increments. So when you read a result, you can see which chip gave the closest to expected results and can adjust your calibration accordingly to 1/6 stop accuracy.

To point out what should be obvious.

A few minutes in the darkroom with a sheet of RC paper and you can turn out as many, and as fancy, grey cards as you want.

The actual reflection density/percent greyness doesn't really matter as long as you use the same card; it becomes your standard.

 

[madNbad]

After searching around for a fiber based gray card that didn't cost a fortune, I found these Mennon cards for less than ten USD. Like watches that need to be synchronized or meters that should be adjusted to match, 18% gray seems to be a moving target,




I'll probably stick with the Mennon. They're new, smaller and I only use them occasionally.

Thanks, this has been a very informative thread.

 

[runswithsizzers]

I've heard there are fifty shades.

 

[madNbad]

I've heard there are fifty shades.

I was going to say, "Pick a card, any card."

 

[madNbad]

Why would anyone need an 18% background?

Booking photos. When agencies started moving to digital imaging, an 18% gray panel was the best choice for the wide variety of skin colors.

 

[DREW WILEY]

Yeah, gray cards are like watches; but those two examples posted by madNbad seem like an entire time zone or two apart.

 

[madNbad]

The Kodak card is the one against the wall and I’ve owned it for years. The $8.95 Mennon set of two cards, 6”X4” and a 8”X6” arrived today,

 

[xkaes]

The Kodak card is the one against the wall and I’ve owned it for years. The $8.95 Mennon set of two cards, 6”X4” and a 8”X6” arrived today,

I've seen some nice incident meters sell for less on EBAY.

 

[Alan Edward Klein]

To point out what should be obvious.

A few minutes in the darkroom with a sheet of RC paper and you can turn out as many, and as fancy, grey cards as you want.

The actual reflection density/percent greyness doesn't really matter as long as you use the same card; it becomes your standard.

Then why not use your palm?

 

[Nicholas Lindan]

Then why not use your palm?

That has been sage advice for a long time - meter your palm and open up a stop. If you want to reduce exposure a bit just hold your hand over your head for a minute before metering.

An 18% card is more a philosophical aid than a practical one.

 

[btaylor]

The actual reflection density/percent greyness doesn't really matter as long as you use the same card; it becomes your standard.

This.