The otherwise is already covered by DSLRs. Canon has it, and I'm sure Nikon does. Law enforcement has been using this stuff for years.
http://www.canon.co.jp/imaging/osk/osk-e3/index.html
Apparently it was broken in 2010 (found while googling for this).
The otherwise is already covered by DSLRs. Canon has it, and I'm sure Nikon does. Law enforcement has been using this stuff for years.