|Some people asked me to elaborate my handhold setup for superteles, so here is it :) . The following picture shows the how I do with it in the field
Now I break down the support part, here is the tool belt with Op/Tech Tripod Strap looped around it. As for the tool belt, I believe you can get it at any hardware store like ACE or Home Depot. I bought mine from the previous owner of my previous 500mm lens :)
Below is a closer look at how I made the holder. You can use your creativity here to make a secure yet convenient holder. And you may not use Op/Tech Tripod Strap at all, some other holder may work better for you. After trying several alternatives, I just feel like the strap the best.
And here is how monopod foot insert into the holder. It's secure and easy to take out and put in.
Now to the monopod head. First of all, I use Arca-Swiss style plates and clamps for all my cameras, lenses, and supports. Since the system is adapted to many manufactures, it's very easy to get high quality parts with many choices. The head I use is described at here. Many people have questioned that since the head is only good up to 6lb according to the spec, is it strong enough for a supertele like 600mm or 500mm? I'd say it good for what we are trying to do here. Sure it won't lock the angle between the lens and the monopod, but we don't need it to.
Also for the lens plate, I highly recommand an adapter plate for 500mm or 600mm. I use 4th Generation CP-61 on my 600mm. It has more clearance than Wimberley's, so I can slip my hand under it when using it as a handle to hold the lens around.
Now you've got my "secrete" of handholding big lenses, it may not work for you (I certainly hope it does). But I really like it, and use it whenever possible. It allows me to hike without heavy tripod and head, and be more agile when following birds in flight. Happy shooting!