Robin Myers Grey Card Article

[davidr]

Can the moderators tell me why my last post regarding an article by Jeff Schewe is no longer available to read?

Reading another grey card selection article recently by Robin Myers, he states the most important criteria for selecting a grey card is uniform spectral response. In other words he is saying that the reflectance from the card should be the same regardless of the color of illumination. That is grey will remain grey and there will be no color cast to the gray.

Are there any plans for tests on the site showing how the WhiBal performs under various lightning conditions together with images to look at? I notice the Bush picture on the front of the site and on my monitor the grey card seems to be reflecting some of the blue in the flash perhaps it is not possible to accurately tell from a jpeg file.

Any help or feedback would be appreciated.

[davidr]

No downloaded the Bush picture and the card is producing neutral grey, the blue cast was obviously just in my mind because I knew it was a flash picture. The card has remained neutral and not reflected back any of the blue light.

May I ask does the higher the temperature of light produce higher and higher grey values going nearer and nearer to full white. For eample the 40 watt bulb shot produces grey of R127 G127 B127 whilst the flash shot produces grey of R172 G172 B172. Am I right in thinking these grey values will rise the higher the light temperature.

After a period is it possible to build up a library of grey settings which will work well under different lighting conditions which might be useful should you forget your card for some reason on a shoot.

[MichaelT]

David, we have always published the spectral response of WhiBal along with comparisons of all known (by me) "competitors". It has been on our site from the beginning. If you want any cards added just let me know, and I will buy one oif reasonable or just send it to me to make the measurements. As you will see, WhiBal meets or beats all competitors. And we have some surprises coming soon :>)

This is the only comparison available anywhere as far as I know.
Gray Card Comparison Chart - WhiBal and "The Rest" (http://www.rawworkflow.com/products/whibal/WhiBalCharts.html)

[wlarmon]

"Can the moderators tell me why my last post regarding an article by Jeff Schewe is no longer available to read?"

What was the article? I missed your original post because this is the first time I've looked at this forum.

Wayne Larmon

[MichaelT]

1 - May I ask does the higher the temperature of light produce higher and higher grey values going nearer and nearer to full white. For eample the 40 watt bulb shot produces grey of R127 G127 B127 whilst the flash shot produces grey of R172 G172 B172. Am I right in thinking these grey values will rise the higher the light temperature.

2 - After a period is it possible to build up a library of grey settings which will work well under different lighting conditions which might be useful should you forget your card for some reason on a shoot.

1 - No, this is wrong thinking. The Gray card under tungsten light will not produce values where R=G=B. The light is toward orange and so the gray card values will be towards orange. If the R+G+B then the light was perfectly neutral in relation to how the camera WB was set and not adjustment is needed.

As far as 2 situations of R=G=B=127 verus R=G=B=172, that would be a situation where the 127 would be a midtone gray and the 172 would be a lighter gray. Ad the R+G+B approached 255 it approaches white, and as it approcahes 0 it approaches Black. Neutral = Black = White = Gray, just with different luminance values. Let me know if this explains it OK.

2 - Yes you can build up a library of WhiBal shots, but not by number, by lighing situations. So lets say that every week you shoot a basketbal game in the same venue with the same lighting. You can shoot a WhiBal capture and use the same one week after week as your reference as long as the lighting has not changed. Of course the real purpose of WhiBal design is that it is so easy to use, that it is easy to shoot a new reference shot every week just to be sure.

[Erik Aalund]

And we have some surprises coming soon :>)[/url]


Hi Michael,
Surprises...... can You tell us a little bit more? :-)

Regards Erik

[MichaelT]

New products, new accessories. it is a WhiBal world :>)

But right now my first prioroity is to fill the backorders that people are patietly waiting for. I really regret this situation...