"RSD99" wrote in message
news:ApmSe.707$Sx4.18@trnddc06...
SNIP
Re the grayscale you desire ... get a Kodak Q-13 "Kodak Color
Separation Guide and Gray Scale-Small," costs something like
US$20 at places such as B&H.


Unfortunately the range they cover is too small for a decent DSLR.

The one you'll need is e.g. the Stouffer T4110:
http://www.stouffer.net/TransPage.ht...mission%20step

It covers a range of approx. 10000:1 or 13.5 stops. That should be
enough to be able to determine the dynamic range with a single
exposure.

Bart