Dear Jeff,

Thank you for the paper, to which I will read later this evening...

As you indicated, there are other spectral influences at work within any scene, and I believed that my meter was continuously influenced by high altitude UV lighting, and because I was suspicious, I decided to add a UV filter to my meter, complete with the meter's extended lens hood.

I cannot state how the UV filter affects the L-558's measurement uncertainty, but I did gain confidence that my shadow detail improved while using the UV filter. When I combine this filter with any decision to expose the scene's important shadow detail at Zone 4, compared to Zone 3, and print the shadow detail down to Zone 3, I do believe that the UV filter adds value to the meter in a positive manner, albeit a very small value.

Calibration is your friend...

jim k