The current news item at Luminous Landscape includes a passing reference to a product so significant I can’t imagine it isn’t more widely available. They mention it today because it has just been reproduced by Hasselblad. This product is the PC Mutar T* 1.4x teleconverter with perspective control. I’ve written about the need for affordable perspective control before, and I see something like this as just the ticket.
Now you can’t simply insert a shift plate behind an existing lens because:
Doing so increases the effective flange-to-film distance of the lens, which shifts the focus plane closer to the camera. Infinity focus is not possible on an extension tube, for instance.
The circle illuminated by a regular lens closely matches the sensor/film format. Shifting these lenses would cause the sensor to only be partially covered by the lens.
The PC Mutar T* solves both problems by adding glass elements that perform a tele-conversion. The converted lens maintains focus ability as the mounted lens’ and now illuminates a much larger circle. The shifting aparatus is then a piece of cake, merely a mechanical challenge.
But that's not all! The Zeiss incarnation of this concept has now been improved upon by Hasselblad. Their new HTS 1.5 adds a tilting mechanism! This is just perfect... any lens becomes a tilt/shift lens when mated to this adapter.
How I wish such a product existed for small-format SLRs! I almost feel like buying a Kenko TC, taking it apart and building myself an adapter.