Quote Originally Posted by neuroanatomist View Post
I'd say it's a judgement call depending on arm strength. The 500 MkI was considered a handholdable birding lens suitable for BIF. The 600 II weighs essentially the same as the 500 I. But, the 500 II is almost 2 lbs lighter.

Speaking personally, I can hike with the 600 II, handhold it, and shoot BIF with it. I do hang a monopod from my belt, in case I'll be standing somewhere for a long time, but usually I move and shoot, move and shoot, and the monopod stays on my belt. I'm not a 'jock', I don't lift weights per se, but the weight of the lens is supported by the left arm, and my left arm has spent the last few years carrying one of my daughters (now 24 and 33 lbs.) for fairly long stretches of time.

If you can go somewhere and set up on a tripod with a gimbal, the weight of the lens is less of a concern. Still, I'd pick the 600/4 II over the 800/5.6. Check out Bryan's ISO 12233 charts. The bare 600 II is noticeably sharper than the bare 800. The 600 II + 1.4x III gives 840mm f/5.6 that's still slightly sharper than the 800, and is 40mm longer and a bit lighter to carry. The 600 II + 2x III is slightly sharper than the 800 + 1.4x III, and both combos will AF on a 1DIV or 1D X with the new firmware. So...I'm not sure I see the point of the 800/5.6 , now.

I had planned on a 500mm lens, but I'm loving my 600 II...
Hello and big THANK you Neuroanatomist!
I really really appreciate your answer even brought from real-life-experiences with the phenomenal 1DX with also fantastic lens EF600 II from Canon!
Yes I think there is good possibilities to handle the new EF600 II with or without a good monopod! Yes I might also need to add a good Gimbal head to my Gitzo tripod.
Of course there is this 2 lbs lighter factor as benefit using EF500 II however with fullframe DSLR it seems to be right to choose the longer focal lenght of EF600 II!

Thanks again for the valuable advice Neuroanatomist!
(I do really appreciate your good input and also reading your nice and clear language, that I enjoy to read - being not a native English language speaker!)

Wishing you Neuroanatomist and of course to your whole family; your wife and daughters (still 24 and 33 lbs. ?:-)) all the very Best and well being and happy shootings with your eminent photographic equipement from Canon!
Charl