Basic Daylight Exposure Guide
BDE, exposure is relative to the distance from the BDE which remains constant. Computation of exposure is easy, the proper f/stop will be f/16 (sunny 16 rule) when using a film speed approximate to your shuuter speed. As an example:
Film Speed is 200, your shutterspeed will be 1/250 at f/16. Film speed rated at 64, your shutterspeed will be 1/60 at f/16. The same would apply to a film speed of 125, your shutterspeed will be 1/125. As another example, take the later film speed of 125, and these exposures would be the equivalents: 1/125 @ f/16; 1/250 @ f/11; 1/500@ f/8; 1/2000 @ f/4; 1/60 @ f/22