Aerial camera designed by Vilho Nenonen in Hämeenlinna artillery museum. The main lens faces down; the two smaller lenses set at 90° angle photograph the horizon, allowing the tilt of the camera to be determined.
<a href="//commons.wikimedia.org/wiki/User:MKFI" title="User:MKFI">MKFI</a>
<span class="int-own-work" lang="en">Own work</span>