Whoa… Big news on the camera patent scouting front today: Nikon appears to be tinkering with the idea with creating a special 35mm SLR replacement back that would turn a film camera into a digital camera!

Japanese blog Egami spotted the patent (No. 2012-242615), filed by Nikon in May 2011 but published just last week, which shows a back cover that replaces the factory one found on old SLR cameras.

Precise adjustment of the “film plane” would be critical for such a device, so it apparently features a mechanism to manually adjust how far into the camera body the digital sensor extends by turning a screw.

Such a device may one day allow old and beloved 35mm SLRs to be transformed into digital cameras using an easily reversible process.

In the future, you might be able to use your beloved film SLRs for digital photography

While digital backs are already common for medium format cameras — and can be made for large format cameras for the price of a house — the concept hasn’t yet made its way into the 35mm world.

On April Fools Day last year, German design company Rogge & Pott pranked the photo world by announcing a product too good to be true: the Re-35, a special cartridge that captures digital photos on any ordinary 35mm camera without any hardware adjustments.

While that would certainly be the Holy Grail of 35mm analog-to-digital conversion — for both photographers and the company behind the product — Nikon’s patent would still be a revolutionary first step toward the same end.

The downside to Nikon’s method would be that the backs would be far from universal; each one would have to be specially made for specific camera models or lines.

This concept is actually similar to how DSLRs first came into the world. The world’s first commercially available DSLR, the Kodak DCS 100, was simply a 35mm film Nikon F3 that had been modified and turned into a digital camera.

Update: Commenter Knut points out that Leica tried a similar idea with the Digital Modul R for the R8 and R9 cameras. It was discontinued in 2007.

Image credit: Nikon FG-20 by ToastyKen