[ThomasThomas]

I don’t understand why a digital device that fits in the old 35mm cameras is not available yet.

That is how they made the first digital cameras. Kodak made a back that would fit on a Nikon F3. 1991

You can get cameras that will use the older lens but the adapter devices just don't work good enough.

[Paladin2]

I tried my daughter’s D800 with some old manual lenses. Worked fine, but way too complicated for her tastes...