[liljj323]

the sigma 300-800mm is a freakin giant...

http://www.e-fotografija.com/artman/uploads/sigma4.jpg

[Dave]

You wouldn't want that hanging round your neck

[P-E]

Originally Posted by Dave

You wouldn't want that hanging round your neck

I wouldn't mind the opportunity

[stepheno]

A free sherpa with every sale

[VikingPhotography]

Only two things lacking in it for my liking

1. Not an f/4 constant

Yes, I realise that it would have added to the size/weight/price, but f/4 makes for a much brighter viewfinder and more versatile lens. If I'm shooting indoors at f/2.8 and ISO 800, I'd have to rack all the way up to ISO 3200 to get a similar shot at f/5.6. With the exception of the Canon 1D Mk III, ISO 3200 is either a) poorly detailed or b) not on option on some cameras.

2. No image stabilisation.

Not too much of an issue at the 300mm position (I've got sharp shots at 1/60 sec on a monopod supported 400mm lens) but once you rack out to 800mm, you better be shooting from a very sturdy tripod and/or using a fast shutter speed. If you follow the old rule of thumb for the Canon 1.6x sensors, you'd need a shutter speed of at least 1/1250 second to get a sharp shot at 800mm (1280mm equivalent).

That brings me back to my first point - you'd need really brightly lit scenes to get a decent exposure at f/5.6 and 1/1250 second, either that, or you're cranking up the ISO value.

Still, everything in life is a compromise and I suppose at £4000 this will make a fair few wildlife shooters very happy