I just got off the phone with Marflex(looking for a part for my Wista), the guy there says that using a Digital Back with a Large Format camera is a waste of time.
He said that that the camera movements and focussing are not accurate enough to take advantage of the sensitivity of digital. That the camera was designed for film and its' variation from a true flat surface and that digital would be too critical of these variations.
I have done pretty exact what you are asking, but I also designed and had custom make a stitching adapter per my requirements since the qualiy ones out there are way over priced and the chaper ones around 200-300 USD are not of suffice accuracy, and all of above with tiny groundglass. My groundglass is 118mm x 80mm and suited also for panoramic stitching beyond what can be accurately visualized using any other stitching adapter.
My lesson is that for my photography (landscapes) it will be much simpler to use a technical camera for panoramics, shift and rise/fall. Thus I will in essence give up tilts and shifts. Because of this reason I have sold alot of quality gear over last three months (plus), both here on GetDpi, LuLa and on Ebay. My stitching adapter is for sale on Ebay, search 'stitching adapter' or look here
http://forum.getdpi.com/forum/showthread.php?t=23733
You may or may not decide you wish to purchase it, and I would assume that it will fit on a Wista since it fits on my Shen Hao YFC-IIB.
What is mentioned in above of focusing is not accurate on a large format for digital back is something which I strict disagree upon, and at least on my Shen-Hao have experienced being fully achievable. Same as for film it may require slight turining back and fourth of focusing knob but was in my experience not difficult. However I believe this also depends on what focal lengt of lenses you use because the focus travel vary. If there would be problem I would recommend to simply make knob attachments that make the outer diameter larger of the knobs!
With wide lenses it is my understanding that the focus travel is short. At least for Schneider 24mm Digietar XL lens I was told by Schneider that the total focus travel from 1.5m to infinity is only 0.3mm, thus I hold for likely that such lens is rather impossible to focus on a e.g. Shen-Hao, Wista of Ebony. This is perhaps why I had problem to acheive focus using my Schneider 58mm XL, or because simply things in groundglass were very small. Do note that I have a quality groundglass on my adapter made by Bill Maxwell, arguably the very best and brightest (it is not even his basic but the Hi-Lux per memory). I used a 6x lupe to focus. With my Schneider 72mm XL and 150mm Rodenstock Sironar-N I acheived sharp focus with not much issue at all.
The Schneider 72mm XL and 150mm Rodenstock Sironar-N are reputable as very sharp lenses. Without actual testing I would say that those are sharper than the non D version of Mamiya 645 AF lenses I have owned. However, other large format lenses may not be. I replaced my Nikkor 75 SW 4.5 with the Schneider 72mm XL due that it was not suffice sharp for digital (while indeed it was so for film). It is thus worthwhhile to ensure that you do use top sharp large format lenses, but not necessarily digital lenses.
As implied by others above digital requires stricter tolerances for focus accuracy and film flatness. However, as I stated above focus accuracy was not the problem for 72mm and 150mm focal length of lenses for me. The tedious was to adjust swings and tilts to zero or to accurate plane for each shot. However, I believe that was a weakness in my Shen-Hao camera since there is not knob to turn to fine tune such adjustment. In a large format camera that feature knobs for fine adjustment of tilt and swinsts, such as by micro adjustments I believe this should be feasible and considerably less tedious. This is reason I wrote in my for sale add that I recommend for studio primarily, however that is just me because I found this tedious for each shot, and also in setting up camera with stiching back for each shot.
In regards to groundglass, well... as stated in above I choose the very best on market and the Maxwell groundglass is frank so bright that I can many times compose without shielding it against light, except of course if sun is shining directly onto it --- also when no clouds in sky! Amazing really. Such groundglass simplifies. Also of course a 6x loupe is recommended, and a 3x magnifies less and should thus result in less accuracy.
Let me also point out that the absolute critical for using digital back on any large format camera, wheather made for 4x5 or even tech camera, is that if focusing using groundglass, the groundglass and sensor must be within a certain error of preciseness in flatness (else you may achieve focus on groundglass that does not match sensor). It is possible to shim the adapter I have, both at adapter plate and groundglass. When they made it I had them adjust it three times
. It matches my 28MP Leaf back.
Current I consider going with Alpa and sometimes using their groundglass for focus using a 6x loupe. If this works I may also get a 6x9 Shen-Hao camera and have custom made a backplate to fit the Alpa rear mount. Why? Because that would assure the tolerances between Alpa groundglass and my back to Alpa tolerances. That Shen Hao will be small to carry and I can use it for tilts and swings for select occassions. Will it work? Yes, as stated in above of my experience it will. The most critical is the accurate tolerance between groundglass and sensor in digital back. Swings and tilts require accurate adjustment. Focus is no problem.
I hope above helps. :salute:
Any questions, feel free to ask me, either here or per email.
Regards
Anders
P.S. It is possible to go with a cheap Chinese made adapter for 200-300 USD, per memory Jim Collum has used one and may still do so by shimming it. However I maintain mine is of higher quality... and at a price which is rather a steal with such groundglass, and which very significantly aids in focusing and in seeing.