Meters Don't See 18% Gray

[David Kwok]

Dear All,

how true is it ?

Refer to the following url http://www.bythom.com/graycards.htm for the actual article

 

[LittleWolf]

Dear All,

how true is it ?

Refer to the following url http://www.bythom.com/graycards.htm for the actual article

AFAIK, it is true. The only sure way to tell would be to read the ISO standard, but it costs money, and it is quite possible that it refers to other ISO standards, which cost more money.

 

[writing with light]

I am not sure about the 18% gray thingy. But then practically speaking, I find that an "18%" gray card works. I went one step further and tried with another darker grey object, and it gave me an almost similar reading on my meter too. So at the end of the day, whether its 18% or 12%, I think that practically speaking, when it comes to taking the photograph, it won't really differ or matter much.

 

[LittleWolf]

So at the end of the day, whether its 18% or 12%, I think that practically speaking, when it comes to taking the photograph, it won't really differ or matter much.

It's almost 2/3 of a stop difference... and you find people here who sn their cameras for repair because they claim their meters are "mis-calibrated" by less than that. Makes you think ...

 

[writing with light]

haha, point taken. but from my knowledge, no one actually sells 12% gray cards right?

 

[LittleWolf]

haha, point taken. but from my knowledge, no one actually sells 12% gray cards right?

How bright a gray card is depends on the angle from which it is illuminated. Let's say an 18% gray card is illuminated from a 45 degree angle - it will give you the same brightness as a 12.7% gray card illuminated straight on.