my long lens is a Tele Vue TV85 scope,, is f7 - 600mm,, I use an Oly E3 on it and love the resolution the system offers,, have included a photo of it,, some want to say it is 1200mm due to the Oly E3 2X crop factor but I just call it 600mm and any of my Oly lens as they are built to the 4/3 format so I don't consider any crop factor these days, just the X factor,,
not the most portable and certainly not to be considered hand holdable but certainly light enough to haul through the woods on the shoulder a brief distance,, I use the system mainly for my bird and wildlife photography,, I normally try to capture my species in the 100 feet or less range and will use a blind or hide when needed,,
I did a crop on the birds breast so you can see the fine feather detail the scope is capable of providing,, the bird was at a measured distance of 60 feet,,
as for those real long distance photos here is one about 250,000 miles out taken with an Old Nikon 990, 3.3 meg camera back in 2001 on the TV85,,
Derry