I know, the heading will sound a little controversial, but here goes:
A 617 (6x17) panoramic ratio/format camera is really a cut-off, cut-down 5x7 inch camera, that is, the length acts as a 3x, while the height acts as a 1x, thus achieving the 1:3 panoramic ratio.
If the same 1x3 ratio is applied to the width of let's say a 35mm camera (and there were such "toy" panoramic cameras, that exposed only a 12x36mm portion of 35mm film), in order to calculate lens equivalents, the formula is roughly:
The 617 lens focal length is equivalent to x 0.2; thus for example, a Linhof 617 with a 90mm lens would give you roughly the same view as a 18mm (90 x 0.2 = 18) on cropped 12x36mm film.
Or, to calculate from 12x36mm film to 2x7 inch or 6x17cm film, you multiply by a factor of 5. Thus a 24mm lens, or its equivalent in digital format, will yield a ca. 120mm lens view on a 617 camera.
Thus: the 21mm equivalent lens on the new DP0-Quattro will yield a field of view similar to the 105mm lens which is found on both the newer and older Fuji 617 cameras.
Here's a chart:
5x7 film 35mm equivalent
72mm ca. 14/15mm
90mm ca. 18/20mm
105mm ca. 21mm
120mm ca. 24mm
135mm ca. 28mm
150mm ca. 30mm
180mm ca. 35mm
300mm ca. 60mm
etc.
Can the Sigma Quattro Zero compete resolution wise with such a large piece of 6x17cm film??
Not when it comes to extremely large prints, no. But when it comes to prints like around 12 x 36-inches wide, yes, it will be very comparable.
Thus, I am seeing in the Quattro Zero a viable alternative to a 617 camera with a pretty wide lens. At least, I will be on the lookout for its release.
The only digital 617 camera currently on the market is very expensive, difficult to use, heavy, needs to be hooked up to a a laptop/tablet, and is simply not handy, even the results are out of this world.
By comparison, the Quattro Zero will be very easy and quick. Its result can also be out of this world, just only you cannot print too large.
For larger prints, use a different camera with a longer lens, shoot sequences and stitch.