Ansel Adams responded to the frequent question, How large a camera should you use? with the now-famous, "As big as I can carry."
He owned Leicas, early Zeiss-Ikon SLR's, Contaxes, a full Hasselblad kit of which is was quite proud, and large-format equipment up to 8x10. His off-the-cuff photo of Georgia O'Keeffe was made using the Leica (just the part on the left, from a defunct blog post from who-knows-where, but Copyright the Ansel Adams Publishing Rights Trust), grain and all:
And one of his better-known images in Yosemite (Moonand Half Dome) was made using his Hasselblad.
(Ansel Adams Gallery image)
Though Adams is associated with 8x10 view cameras, he photographed in a range of formats. Photos of him making photos for
Fiat Lux, for example (a book cataloguing the UC system), show him using a Sinar 4x5 camera and a Hasseblad. Pictures of his darkroom show three enlargers of different sizes. Convenience sometimes counts, and the 645 cameras are much more convenient to use than the 6x7 cameras, particularly in Pentax's case.
I will probably not shoot 645 film very much any more, as I have not for several years anyway. But 645 digital will be a standard medium for me, even though I'm not selling my Canon kit. But the Pentax 6x7 is almost a religious experience for me, as much a delight to the eye and hand as a machine as it is to the image. I will always make photos, at least at some level, with that system, just as I do with my Sinar. For me, it won't be "better" than 645 digital, but just different. Up to maybe 10 years ago, the 645N and NII were a fast-handling, hand-held cameras for commercial work (or personal work that goes down like commercial work), while the 6x7 was more for simple pleasure.
6x7 is the smallest film format that allows me to make 16x20 prints with an sense of endless detail, which is the standard to which I want to more consistently attain,
when I'm photographing with the intent of making prints.
But it is quite often heavier than the heaviest camera I can carry.
Rick "noting that Adams didn't like printing that O'Keeffe picture larger than 8x10" Denney