Towards the end of binocular production, at a time when only the 6mm of the aging CF29 came close to the ideal, and those of the Porro-I glasses on the company's lists ranged between 3.6mm and 4.7mm, the new CF60 had just such large, 7mm exit pupils. This suggests that its targets were customers who required an improved night glass, the bulls eye being the Royal Navy's supply department. No CF60 has yet come to the author's attention, but photographs in the company archive indicate a screw-plugged vent on the top of each prism box. This tends to verify that the CF60 was made, like so many of its predecessors, with maritime requirements in mind. The presence of the plugs also indicates that Barr & Stroud, like most other makers on the day, never really won the battle to make a waterproof binocular. Nonetheless, pamphlet B.70 claimed that the CF60 was "completely sealed against the ingrain of water and dust and there are few moving parts to be effected by sand or grit.
WE'RE CERTAINLY NOT AFRAID OF ZEISS by William Reid (pub. National Museums of Scotland).