i've been sorting through macro options trying to find the best balance. tried out a bunch of lens/extension tube combinations.... using the kenko 68mm (12+20+36) kit with aperture contacts. best magnification is with my dfa 100mm macro... compared against da*200, da*300, da*55, and a reversed 50mm 2.0, and a reversed 28mm. with a reversed 28mm the magnification is crazy.... but not worth it to lose auto aperture, and if you want to get closer than 100mm with 62mm of extension tubes, then add the raynox.. adding extension tubes to the 200 and 300 does bring closer focusing(at a greater distance than the 100mm, which is a plus), but not 1:1. close enough for medium sized frogs or large dragonflies, but not close enough for beetles or crickets or flies.
unless pentax makes a 180 or 200mm 1:1 macro in the future (that i can afford), than the best choice for me is to use the 100mm 1:1, a set of auto aperture extension tubes, and the raynox 250. i tried the canon fd 200mm 1:1 macro with a fotodiox K mount adapter (took glass out... was HORRIBLE with glass in it) but the lens was not nearly as sharp at the dfa 100mm, and had ca, even when stopped down. nikon makes a great 200mm 1:1, and canon makes a crazy 5:1 macro... sigh.
also just bought a 70mm spiratone bellows macro... gets to around 2.4:1 max magnification... and pretty sharp at f16... but i wouldn't use it seriously.... fun for $20 on ebay.
---------- Post added 10-09-15 at 03:40 PM ----------
also, this guy seems pretty awesome. pentax user, very helpful