The right lens as far as i have been able to verify is a fixed .92 lens. The other presentations i have seen using the zoom 1st and 2nd zoom lens where not to my liking and I heard poor reviews as to the sharpness of a DCI 4k presentation for Cinema Owners in Germany a couple of weeks ago that was described also as soft.
I know TI is working on newer sharper lenses for 4k, although most of the 2k lenses are certified by TI they are nowhere near as good as to what was accomplished in Moody Gardens. Therefore the right lens for now is the Moody Gardens Lens.
Don't get me wrong I am sure the current batch of lenses performs ok with dci content, just not as good as the fixed non zoom lens.
The newer TI zoom lenses that will be better for 4k unfortunately will be in the medium to longer range, not the levels 1 and 2 where they are needed the most.
This Barco fixed lens commands a hefty premium but on America's Largest Imax screen (a Severtson) it performed flawlessly with everything they threw at it.
Isco Schneider will have 4 short throw fixed lenses in the .95, 1,1.15 and 1.2 TD to fit the Barco, the problem is the lenses are huge and may not be well supported structurally by the lens holder design.