That idea floated around for several seasons, but in recent years as digital cameras have caught on with consumers, it has faded away. Although an actractive concept to those with 35mm SLR cameras the engineering necessary, I believe, was beyond practical possibilities, and what might have been possible given the space available, would not achieve an acceptable result at a cost that anyone would want to afford.

The closest thing that exists are the digital backs for medium format SLR cameras. And if you look at what is involved and what those backs cost even scaled down to work with a 35mm SLR the cost is nowhere near what most people would be willing to pay, especially considering what a Canon Digital Rebel sells for today.

It resides in the museum of instant obsolescence. I forget the name...anyone remember it? We actually reported on it as a prototype years back but there were to many problems. David is right about it being not necessary now. The only thing you can swap these days is lenses.

The answer was in David Brooks column from June 2000. It's the Imagek EFS-1 from Silicon Film Technologies

Maybe I've just been around too long, but this dicussion makes me think of the one 35mm SLR that if it were still around today would be most adept to be both a film and digital camera in one body, the Rollei 2000.