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All the previous calculations are based on using the Zörk Panoramic Shift Adaptor to the fullest extent of its shift capacity: 22mm in either direction.
Some wide angle 645-optimised lenses are hence taken into the badlands beyond that which would be recorded on film. The smaller image circle projected by these lenses is often of inadequate resolution for modern digital sensors. Only the very best of them are useable.
Most users and testers concur on the superiority of the Pentax 645FA 35mm for the smaller format. All Hasselblad optics are designed with large image circles which makes them especially useful for our purposes. Some 6x7 design also retain excellent resolution across wide image circles: notably the Mamiya RZ lenses and certain Pentax 67 series optics.
Your densely populated digital sensor will place ruthless and unprecendented demands on medium format lenses, especially away from the central sweet spot. A great stitching lens has an image circle that combines quality and quantity: no easy task for wide FOV designs in particular.
While on the subject of field of view, the point needs making that placing a 80mm lens in an adaptor and mounting it on a digital 35mm body, regardless of sensor size, doesn't change it's focal length: it will still be an 80mm lens. However, the Zöerk shift adaptors allow us to map out a big enough chunk of its image circle to retain its original FOVx (horizontal field of view) or FOVy (vertical field of view).
So when we read that a 35mm lens designed for 645 gives a similar view to a 21mm lens on the 35mm format, we can recreate that FOV one frame at a time, and stitch it together so that the assembled file will look like a 21mm lens again.
In fact, when creating 3.3:1 panoramas, we can push beyond the 120mm film frame on the central axis and created even wider FOVs than the lens was designed to produce: so that a 645 35mm lens can be cajoled into behaving more like a 17-18mm lens with heavy horizontal cropping. For more details on how all this works, watch this space....
The Missing L-Bracket
If you've ordered a tripod mount PSA with a view to regaining the view camera functionality you lost when you went digital, it may come as a surprise that the system you're buying is missing a key component: the L-bracket.
Only with an L-bracket can you seamlessly switch from horizontal to landscape orientation stitching and generally get the best out of your Panoramic Shift Adaptor when emulating rear-standard movements. Unfortunately, at the time of writing, no custom designed L-bracket for the PSA exists, so most users attempt a little Dremel-wielding mod and gain a little seat-of-the-pants, trailblazing, pioneering satisfaction.
The problem is that the Zörk tripod mount has a broad, flat foot that won't quite fit into the otherwise perfect RRS bracket which is reinforced with a raised flange on all its edges. The solution is simple: hack a bit of it out, like this:
Everything should now work perfectly and you should be well on your way to churning out magestic and monstrously detailed images of ineffable splendour, like this one:
Agency Commission, Birmingham skyline, 2005