Originally posted by Paul the Sunman Yes, this is the big issue for Pentaxians at the moment. Is it worthwhile to continue to invest in APS-C lenses, or should we wait to see what Pentax FF looks like? Personally, I dread a future where all DSLRs are the size of the Canon 5D Mk III. Although I hope and suspect a Pentax FF will be somewhat more compact than that, its the size and weight of a bag full of FF lenses that concerns me most. So let's hope for a bright APS-C future at Pentax.
My acquisition plans were for Nikon, a nice shiny 80-200 f2.8 has been holding my attention... but if Pentax decides to announce a new 24mp APS-C or FF camera I will put that on hold for whichever one gets released.
I think this is where Pentax can excel and carve out a nice little pocket for themselves. The D600 is currently the smallest FF camera on the market. I got it sitting here next to my K5 and they are very similarly sized... but the D600 is more uncomfortable to me, so I had to buy the grip. The K5 fits me like a glove.
With Pentax's egronomics I think that if they had to grow the K5 even a little bit to get all the FF goodies in there it still wouldn't be all that big. D600 sized max, and I wouldn't complain about that.
As for lenses, the FA Limiteds, DA 40mm limited, and DA*55mm limited are all proven to work on FF as tested on film, so why shouldn't they work on a digital body? I've also tested my DA*50-135 on the D600 with an adapter and have had very minimal vignetting even wide open... could it work? I don't know. These lenses are still compact. The DA*55mm 1.4 is a slight bigger than the Nikon 50mm 1.8G, but it's also faster... I don't have the 1.4G so I can't compare them, but I bet they are similarly sized.
The Pentax gear *fingers crossed* will also be much better built than the plastic toy like builds from Nikon. The D600 feels like a plastic toy with the 50mm 1.8G on it, compared to my K5 with FA 31mm limited.