It strikes me as strange that nobody asks this sort of question when adapting 6x7 lenses to 24x36mm FF.
On my shelf are ILC cameras capable of shooting APS-C, 24x36mm, 6x6cm, 6x7cm, and 4x5". Other than keeping straight the conventions for "wide", "normal", "portrait", and "long" for each format, I don't really have any concerns regarding replicating a "look" between cameras. In short, it ain't going to happen and the rules are "horses for courses". Comments for each format run like this...
- APS-C: Love my K-3, but still find it hard to find quality wide angles at moderate price in the 15mm to 20mm range. F/1.4 wide angles? (rolls eyes) It is hard enough finding focus at f/2.8. For macro and extra reach, APS-C is so very nice, particularly since cheap and ubiquitous fast 50s work so well for portraiture with this format.
- 24x36mm: Sweet and familiar after over five decades shooting in this space. Fortunately what I learned there is applicable to APS-C and vice versa.
- 6x6 and 6x7: True medium format film was a revelation.* Yes, there is potential for amazing quality, but DOF is dear (there is often very little to work with) and lenses are slowish. Amazing how ISO 400 is the new ISO 100.
- 4x5: Everything from medium format plus the note that large format cameras have movements for a reason. DOF is so limiting that many subjects are inaccessible without manipulating the position of lens to film. Fine focus is done using a magnifier loupe on the ground glass and DOF is estimated based on experience. Macro 1:1 is usually easy to accomplish, but with a 6" frame diagonal, subjects are usually not very small.
Now if someone wants to dial in 2/3 stop narrower aperture moving from 24x36mm to APS-C while bumping the ISO down to allow the same shutter speed and equivalent noise to a larger sensor, that is fine. If doing so fits one's flow, it is fine with me.
Steve
* I dabbled with 645 film at one point and found the negative to not offer a whole lot more than 35mm film.