Minolta Junior B.C.
|On accessory clip of a Minolta-16 II|
image by Nick Zamora (Image rights)
The Minolta Junior or Minolta Junior B.C. is a flashgun for older-style large flashbulbs. An adapter for modern small bulbs was available. 'B.C.' means 'battery/condenser'. That means that enough current for flashbulb ignition is drawn from a capacitor charged by the 22.5V dry battery. The flashgun has a collapsible reflector fan of 13 blades. On the back is a small analog calculator for computing an exposure parameter (probably the guide number) which is depending on lamp-to-subject distance.
The Minolta Baby flash is a smaller variant with an 11-bladed fan.