Browsing through my local Ace hardware I stumbled upon a KAPRO PostRight multi-function spirit leve. Very lightweight (red plastic material) with three large green levels and easy to see. It is like a little book with a cerntral hinge (click-stops every 15 degrees) and fits like a charm on the bed of my 5x7, 8x10 and 11x14 beasties. Really helps with leveling and for less than $8.00.
I think was a bargain, so thought I would pass the info along
I had two of these, I had them mounted in my jeep - used them to give me some idea of when the beast was getting ready to tip over - that can be scary off road. -Never thought of using them for camera work