What are five exposures equivalent to F8 at 1 60 but use a faster shutter speed?

Assuming a 1 stop increase between speeds, they would be: F5.6@125; F4@250; F2.8@500; F2@1000; F1.4@2000 Since most people are not likely to possess equipment capable of 1.4 and 1/2000, I would propose using an ND4 filter and a combination of F2.8@125 instead.