Blue Sky = Middle Grey

[octopoli]

If you take a spot reading of a blue sky is that close to a middle grey reference? I have always read that grass is close as is a cloud with grey in it but I came across a few references as a blue sky as another one.

This would seem helpful if you were inside and wanted to expose for the properly expose for the outside creating a silhouette all you would have to do (if the sun was not beaming in frontal) is spot a blue patch of sky.

I wanted to see if this actually could be used at times as a good middle grey reference with a spot meter, of course if you were in shade of some sort (ie trees, tunnel, etc) it wouldn't work.

 

[David Mullen ASC]

Yes, a blue sky is a good middle grey reference, though for a good silhouette shot, it helps to actually have the background slightly hot to create a good contrast for the black shapes to be framed against. And generally the sky isn't the main background outside of a window unless you are in a skyscraper, so there may be something else better to meter.

I generally only use the blue sky as a middle grey reference for a spot meter when doing shots of skies and clouds, or sunset shots.

Cement sidewalks are close to 70 IRE, i.e. one-stop over middle grey, skintone reflectance area, so can be a good reference too especially when using a video camera with zebras.