Originally posted by jjbacoomba . . .
Does anyone know if there actually is an A button?
. . .
Short answer:
Yes.
Longer answer:
Over the past several years, I've bought three different Samyang made lenses in K mount and they all have the "A" setting. I don't have the latest generation of 85mm in K mount, but here's an excerpt from
B&H's overview of the 85mm for Pentax:
"This lens features a mechanical aperture coupling that permits the use of aperture priority and automated exposure modes, as well as the ability to control the aperture setting with Pentax DSLRs"
So it sounds like you're good to go. Those big retailers are just too lazy to actually show the Pentax version of the lens in their listings. It's easier to just paste in a stock photo of a Nikon or Canon.