This question is for one of our camera experts on the forum.

I recently was talking with a co-worker who is not into hiking, and he was an older photographer still using the Mamiya RB67, a larger-format (2&1/4x2&3/4), rectangular roll-film camera that I remember from decades ago. He said the market had about bottomed out on it for resale, so he was going to hang onto it; he's one of the last people I know to have not gone digital. He said that he was considering buying a digital back to replace the film back.

Is this viable? I think I've heard of shooting digital for preview and test shots and then shooting the final photo on film, but can you get a back with a sensor that big? (Maybe so, since he said the back alone was $9K.) And if there is a sensor that size, my god what is the resolution or megapixels on something that big?? Is that what the great hiking, outdoor-photographers like John Fielder are using to get such incredible landscape shots?

(Speaking of John Fielder, anyone coming to Denver and looking for something to do in Denver before they're dead, should stop by his gallery on Sante Fe near downtown. He and a group of other outdoor photographers have an expansive gallery of photos. On the first Friday of each month, the entire Art District is open late to peruse before heading to Strange Brewing for an IPAphany Pale Ale.