what is the best keying software for doing green screen is it shake?
well most keyers are based on a plug in from 3rd party companies. shake has 2 awesome keyers built in (though they are from 3rd party vendors); keylight and primatte.
i like to use primatte as my primary keyer, but every keyer (including luma key) has its benefits and you will find yourself using more than one keyer per shot. i recommend watching one of the gnomon shake dvds called "effective keying techniques" to learn the major purposes of each keyer and when to use them.
here are a couple examples:
for this i had to use about 4 keyers and a couple roto shapes to help bring back important edge detail that was lost through color bleed, fragmenting, and interlacing of the crappy SD footage this was shot in.
http://www.whitecrowproductions.net/video/s10\_7\_compare.mov
on this website i was able to get away with doing a single primatte keyer and it came out great (even with the terrible lighting with no rim light haha)
http://www.slowlyrotatingblackman.com
is smoke any good for keying as i've just got a license for it?
smoke is a great tool for all in one editing workflows...if you a person with heavy deadlines and cant spend time sending stuff from software to software. i would say if you want to get down and dirty with a composite like getting keying work done to the exact way you want it, then use a dedicated compositing app. you will have access to lots more tools and solutions to problems. it also focuses your processing power, ram, and dedicated video memory to that one aspect without it running an entire computer intensive piece of software.