- When does Nikon announce significant new DSLRs? Typically February, March, and July-September (25 of of 34 announcements in past twelve years).
- When does Nikon announce significant new lenses? Same answer: February, March, July-September (51 of 68 announcements in past twelve years).
- How many DSLRs does Nikon typically introduce a year? The average is 3, with a range from 1 to 5 over the past 12 years.
- How many lenses does Nikon typically introduce a year? The average is 5, with a range from 2 to 9 over the past twelve years.
Thom's predictive DSLR history (updated August 2015):
Note that Nikon is shifting priorities and time schedules a bit in recent times. DX cameras have drifted off quick update schedules to slower ones. FX cameras have been a bit unpredictable (other than the pro bodies, though even there we lost the expected the D4x).
The individual announcements year by year: