An illuminated rangefinder accessory for the Nikon SP, released in March 1958.
The exact production number is unknown, but it's believed to be very limited — and working examples like this one are especially rare.
It runs on a single AA battery.

Flip the switch in the dark, and the lively SP viewfinder softly lights up — a truly magical sight.
Regardless of practicality, this is one of the most unique accessories Nikon ever made. A real oddball, and a collector’s delight.

This one is in very clean condition with minimal signs of use.
There’s a marking S on the bottom of the shoe, but it’s hidden when mounted on a camera.
For this accessory, it’s in outstanding condition overall.

Professionally serviced in April 2025, and despite its size, it lights up with surprising power .