On our recent project, Noble, we rented one mama-jama lens (among some more standard ones) to pull off a couple of shots. The thing is mammoth, we had a lot of fun with it so I thought I would share some behind the scenes pics of it.
The Canon EF 400mm f/2.8 lens WITH a 2x Extender in place.
With Lens Hood and Extender on a T mount (for sniper perspective shots):
Prepping on the dolly:
To compare between the two, here's the same shot through a 50 mm and the 400 + extender, before any color correction:
50mm (7D 1.6 crop factor)
800mm (7D 1.6 crop factor)
Was a lot of fun, but obviously not something you use often.
The Canon EF 400mm f/2.8 lens WITH a 2x Extender in place.
With Lens Hood and Extender on a T mount (for sniper perspective shots):

Prepping on the dolly:

To compare between the two, here's the same shot through a 50 mm and the 400 + extender, before any color correction:
50mm (7D 1.6 crop factor)

800mm (7D 1.6 crop factor)

Was a lot of fun, but obviously not something you use often.