It's hard enough to judge % shade by eye, and even harder to do it by eye from a photograph.
Seeing as you have a camera, with a piece of white paper you should be able to work out the foot-candles; I detail the technique in a blog post
Orchids on a Balcony: New Gadget: Light Meter.
In brief, Using a piece of white paper, with the camera lens at a distance of about 30cm from the paper, at f2.8 with a film speed (ISO setting) of 200, the shutter speed is approximately equal to foot candles. If that sounds like too much maths to you, First Rays have a handy form you can fill in that
works it out for you.
If you hunt around, you should be able to translate the FC reading into %shade.