A while back, I became enamoured with Fuji's wonderful panorama cameras made for 120/220 film, the G617 and the later GX617. I found a seller on Craigslist and almost decided to purchase it. Besides the film and processing costs, if I wanted to do any digital post-processing it would require buying a scanner capable of scanning the negatives. (A scanner like the wonderful Epson Perfection V600 Photo, which even comes with a 6x17cm negative holder).
I also considered a panorama film camera which produces a similar aspect ratio on 35mm film, the Hasselblad Xpan™ (and later Xpan II™) which in turn led me to the Fuji 35mm offerings the TX-1 and TX-2. Besides again requiring the expense of film and processing and scanning, they are also pricey.
I guess that's why I was intrigued when I saw the Fotodiox RhinoCam™. It seemed like a way to get the same results as those cameras, but straight to digital (although requiring image stitching).
Therefore, my design for the Pentax HippoCam (at least Version 1) is to allow me to take a 6x17 aspect ratio (or something close) directly onto digital. The Pentax K-5 family sensor has dimensions of 23.7mm x 15.7mm. That means that if I orient the camera vertically and take 6 exposures, with an overlap of 4mm on each image, then I should end up with a stitched image of approximately 23mm x 74mm (23mm x 65mm would be exactly the ratio of a 6x17 negative).
You'll notice that my 74mm is actually longer than the original length of the 6x7 negative (70mm long). Whether that will actually be achievable or not, remains to be seen: Even if the image circle extends far enough the image quality at the edges may suffer to an unusable degree.
Next we will look at some of the pieces of this little puzzle (subject to change without notice).