15mm with 2x teleconverter?

im looking to shoot some seahorses in a bit and im fretting over which lens to bring. i have a 50 mm macro lens that i use on my casnon 1000 d, but also have a 15 mm fisyeye that i was thinking of pairing with a 2x teleconverter. im wondering if the tele will help bring the image large enough with cfwa technique to make it fill the frame. i think the seahorse is about 3-4 inches high. or am i better off sticking w macro?

macro first. if its a really beautiful locale perhaps its worth trying the cfwa, but i'd see that as something to try after i've shot some nice macro pics. 2x teleconverters really rob sharpness & light, i'd suggest a 1.4x or 1.5x. I'd only ever use a 2x with the sharpest of lenses (like super-tele primes). also see what repro ratio you can get with the combo topside, and you will get less than that behind the dome's virtual image. and is your dome small enough to get close & light it?

by all means give it a go, but i wouldn't only shoot that. so i'd say do both if you can. cheers,

chris