Ah Hans and Klaus,
Absolutely.....if I can manage with shuttertime and aperture I shoose those of course. But shooting handheld with a 400 is a different ballpark from shooting with an 85 on a Seitz mount. Then you will eventually have to creep up the ISO and the Nikon D800 can do that to 3200 ISO easily. Of course you will loose some fine detail (which can be limited if you shoot RAW btw)....but you are shooting for "on the wall" so for print. And that means with a Nikon D800 you can still get a 13 x 20 inch out of if without loss of VISIBLE detail Klaus (unless you go to exhibitions with magnifying glasses strapped to your forehead but somehow I doubt that
(Imaging resource yelps 24 x 36 but I doubt that as well, 13 x 20 I've tried myself with a borrowed D800e)http://www.baur.nl/gereedschap/vergrootglazen-en-loeplampen/vtmg13-hoofdband-met-vergrootglas-en-ledverlichting.html
Shooting gigapixel means aiming for pixel detail and that is quite a different game alltogether, first you have a stirdy (at least in my case I have not tried or even seen other motorized panoramamounts so I can't comment on that
) platform to shoot from so you close down the aperture and increase shuttertime to match.
But shooting long tele's handheld (up to 600 mm) will mean going at shutterspeeds of less then 1/2500 of a second. Now in order to achieve some DOF you have to stop down to F8 to F11 (in my case) and that means ISO's of up to 1600......now that means no pixelpeaping possible but great in print.
Des's solution on a shoestring budget is simple:
1) Go a gym and find the inner greyhound in Des......
2) Learn to think print (which means pixelpeaping has to be trown out the window since it is quite useless)
3) Heath Klauses advise and shop for a 300 fixed.....you could even use a manual lens (a bit tricky for shooting wildlife but hey Baron Hugo van Lawick and Frans Lantink shot wildlife without an autofocus so why can't you, you'll need patience but that is essential in wildlife anyway. And for Nikon the 300 mm 4.0 IF ED is about the best you can get or you can insist on AF and buy this baby secondhand:http://www.kenrockwell.com/nikon/3004af.htm
they should do about 1000 dollars or less (less is more in this case). Also be patient. I bought a manuall 300 mm IF ED for a song and a dance once.