Undoubtedly, format ratio is a matter of personal taste, however, I don't think that "square" would be a wise choice for an MF maker to produce since its appliance is to a small percentage with respect to other formats. Additionally, a "square" FF sensor would only be applicable with Leaf shutter lenses since there is no focal plane shutter of the size made any more which would limit its use to only V-blads and Rolleis… I also believe that Leica's choice to use 3:2 ratio, is a wise one for the following reasons:
1. The advance to their system is more friendly to DSLR users.
2. They where able to reduce the mount to image area distance and thus make the camera compatible with others lenses and even made possible the integration of Leica S into an existing system easily.
3. It made calculation of AOV with respect to DSLRs easy (one has to subtract 20% out the focal length he uses and have exactly the 35mm equivalent focal length for the same AOV), Additionally the introduction of the 24mm lens solved the UWA capability of the camera.
4. The corner performance of the compatible lenses is greatly improved.
5. It gives additional choice to the Sinarbacks (which are all of 4:3 image area) without competing with them.
6. It improves "handhold ability" greatly than other MF systems.
Take a Contax user for instance (my case) that wants to advance to a modern back, if he buys an S instead, his 35mm becomes a 28mm (35mm equivalent AOV), his 45-90 becomes an ideal 36-72 standard zoom, his 120mm Apo an excellent 1.2:1 macro of 96mm, and his 210mm a great 168mm telephoto, he only has to consider the 24mm if he wants to go wider (19mm equivalent). Additionally, he can keep his MS back and have ultimate still life performance, have 4:3 tethered in studio for fashion or portraiture …use film whenever he wants and even return to his Leica and use the same lenses for landscape or even walk around (!!!) camera. All that by investing not a penny more, than buying a new back.
I bet that if Leica will release a couple of new adapters that will make Rollei lenses fully compatible and another for Mamyia 645 lenses or even more adapters for the various Bronica lenses, (all of which the intelligent mount design can use as fully dedicated via an adapter) there will be more trouble for MF competition… It will then have the widest base of lenses in the market by far and the widest base of possible customers without excluding current users of direct competition. Look how much it affected Hasselblad H sales and look at Hasselblad H S/H prices… imagine what may happen if they will offer an adapter for Phamyia too and serve via more adapters the (now homeless) older camera users?
Clearly image area size and the lesser resolution, doesn't seem to make a difference in performance for current MF users… The quality of the image is (at least) as su-pe-rb if compared with any competition, it's the solutions provided that make the difference and final cost.
