While Leica hardly (if ever?) releases a lens, any lens without ensuring near perfect optical performance and virtually perfect physical attributes, what results is that the S2 system has a limited series of very select lenses which attain the extreme pinnacles of performance!
What I suspect is that Leica also has the practical photographer in mind, and the result is a series of extremely precise adapters which allow the use of Mamiya 645, Pentax 67 and Hasselblad manual focus lenses.
Looking at the bottom of the S2, two distinct images emerge.
One is the double tripod bushing which caters to both standard 1/4" BS Whitworth thread and the 3/8" thread.
The other is the very innovative battery chamber double-tap lock.
Upon moving a lever, the battery releases about 1/8" downwards, and stops there. Double tap it and the battery falls right out. Very ingenious for photographers who sometimes do not cradle one's hands under the battery and it go crashing to the floor, or over a canyon!
As for the Leica S2 battery itself, this thing had
JUICE!
I did a Food Shoot which lasted over 5 hours, and because I focused everything manually, I chimped NON-STOP through out the 5 hours! At the end of the day, the battery only depleted 20% - 40%.
Since most of my shoots involve natural light, or multiple mono-blocs, I didn't ask for the very proficient, and efficient Leica flash units (made by Metz). I've had many experiences with Metz units to know what they're capable of.
For a reference of all the S2 accessories, please go here:
LEICA Camera AG - Zubehör