Two kinds of gray (grey) cards?

[burtharrris]

I recently bought a digital photography book, and in the back it had a card with black, gray, and white on it. I read the chapter in the book about setting your photoshop Curves to the white black and gray colors, and I really like the results. It's a quick fix to make pictures much more lively.

The point is, I have an old gray card from back in my slide and B&W film days. But it's gray color is much darker. When I balance the image to the (dark) gray card, it doesnt have the same look; it's flatter and darker lighting. Is the old dark gray card obsolete for color digital photography?

Thanks!


(By the way, I HIGHLY recommend the book for its image processing techniques, it goes past the basics: The Photoshop Book for Digital Photographers by Scott Kelby)

 

[Alpha]

Probably different % grays. Do the cards say the percentage?

 

[astrostu]

Yeah ... gray/grey is simply not black nor white. Depending upon printing/dying accuracy in making the card, there's ((2^8)-3), ((2^16)-3), or ((2^32)-3) other shades in there that are still gray/grey. (-3 because -1 for sign, -1 for white, and -1 for black.)

 

[ann]

it could also be an aging factor.

i just looked at the card you talking about and the midtone gray is the same tone as a gray card i have.

 

[burtharrris]

That is very possible. The book is 4 years old and has been sitting on the shelf in my town library for awhile.

 

[Mike_E]

Ansel Adams lobbied Kodak for 18% grey and got it. It seems that is what best suited the Zone System.

Modern camera makers use a different- 12%- grey to calibrate their meters at the factory.

Here is a link to Thom Hogan (quick google scan)

http://www.bythom.com/graycards.htm

I didn't read it beyond a quick scan, he may have better information on the wherefore's and the why's of it all.

m

 

[jstuedle]

Another factor to look at is Kodak grays are made for film. You might find the film gray cards to have a slight color cast that will slide any WB off center. I use a card sold by Photo Vision and marketed by Ed Pierce. It has the W/G/B side that helps center exposure by histogram. I also shoot a frame of it any time I go into a different lighting condition. In post processing I can batch adjust for minor WB shifts for the whole shoot in those lighting conditions. The flip side is a handy reflector for shadow fill.