The Rangefinder version of the Baby Sibyl was brought out in 1939. Very few could have been sold as it is now extremely rare. It is essentially an ordinary Sibyl to which has been added a rangefinder running vertically along one side. The coupling is quite simple, the lever that moves the mirror is matched by a similar lever on the inside of the camera body which touches a peg on the lazy-tong strut. The strut moves during focusing and so moves the lever. By 1939 few Sibyls were sold, they looked out-of-date and were expensive. The price was £21.0.0 which was £3 more than the ordinary model. The position of the focusing lever is not good, the rangefinder tends to be obscured by the hand.

There are minor differences in the rangefinder windows between examples. Later examples have a much narrower lower window than earlier models, the upper circular window also differs slightly in size.

The hooded focusing screen and close-up lens with the second example shown here are unusual.