I find it strange that there is such contention over a definition (of photographic format) that has existed for over a century.
Photographic formats, traditionally, are defined by the size of the camera's negative. With those different negative sizes come some differences in the way the lens/camera draws. In film, some format examples are 8" x 10", 5" x 7", 4" x 5", medium format (60 mm x various) and small format (24 x 36 mm).
The primary reasons that pictures made from small format negatives often look different from those made from medium format negative are:
1) 35 mm negatives are smaller and thus must do more with less.
2) 35 mm cameras are paired with shorter focal length lenses for any given field of view
The area of a 35 mm film negative is just about 20% of the area of a (medium format) 6 x 7 (cm) negative. Most photographers have long understood that this means the two cameras are of different formats and will tend to draw somewhat differently.
The CCD area of a typical small sensor camera (which measures about 7.2 x 5.35 mm) is about 4.5% of the area of the sensor in a Canon 5D (or, of the area of a 35 mm film negative).
When one is working with a camera that uses a capture area that is 4.5% of the size of a 35 mm film negative, he or she is working with a camera of a different format. That size difference, by definition, is what separates one photographic format from another.
Clarity of language and semantics are two very different things.
One may indeed be able to mix a set of prints made with different cameras of different formats and find that people cannot tell which camera made which. But that doesn't mean that differences in formats, and among cameras and lenses, do not exist.
Small sensor cameras, as a format, are marked by a few general tendencies:
1. For a given field of view and a given aperture, they show dramatically more depth of field, than cameras with larger sensors, because they use shorter focal length lenses.
2. Their dynamic range, overall, tends to be narrower than that of cameras with larger sensors. One must be willing, under some conditions, to allow the highlights to blow out and/or the shadows to go to black.
3. Their tonal gradiations, while often beautiful, tend to be somewhat more abrupt than those of cameras with larger sensors. At any given ISO, their drawings tend to be somewhat coarser than those of cameras with larger sensors.
4. Their noise levels, at a given ISO, tend to be somewhat higher than those found in cameras with larger sensors. (Just as 35 mm negatives tend to show more grain than medium format negatives.)
Its no coincidence that Chris' opening post talked about three differences between his M8 and his GR2: depth of field, noise and DR.
Just as one can sometimes make a medium format film camera draw like a small format film camera, so too can a camera with a, roughly, APS-H size sensor (for example) sometimes be made to draw like a small sensor camera. With a plastic medium like photography, there are certainly a lot of ways that pictures from any camera can look. But, I would continue to urge photographers working with small sensor cameras to get to know the nature of this format, of its strengths and weaknesses, and make good use of them.
As I've written for the past two years, I think that photographers who want to use this camera format seriously may want to begin by considering what its nature is. These cameras are part of a very young format that, if used well, can lead to very interesting work.
How important is format to one's work? Stephen Shore very intentionally uses an 8 x 10 camera rather than a 4 x 5. The differences between the two are not trivial to him. Evans changed formats according to the kind of pictures he was making. Strand stayed with large format for most of his career. Larry Fink moved to MF rangefinder cameras because of the specific look their negatives create. The examples could go on for pages and pages. There is no one best format but one's choice of format can indeed be important to one's work.
Aspect ratio, of course, is a whole other kettle of fish.
Cheers,
Sean
P.S. Van Gogh had specific tastes in paper, paint and brushes. His letters to his brother Theo make this very clear.
