Toronto. Like most optical houses in the 1800s, The British house of R and J Beck at Cornhill (London, England) expanded their optical product repertoire to photographic lenses (and cameras). In this seventh edition of Conrad Beck’s small book, like all microscope makers do, Beck endeavours to educate the rank and file user. In this case, it is the advanced amateur or professional photographer, on the technicalities and scientific principles of photographic lenses (Authorship is given to Conrad Beck and Herbert Andrews). Many universities have digitized various editions in recent years.
While my copy is strangely undated, this 1920 edition covers the Beck Isostigmar which was first announced in 1906. The book also covers exposure calculators and “instantaneous” shutters of a couple of seconds to as fast as 1/80th second. Such calculators and shutters were never required before the dry plate era of the late 1800s.
We often think of auxiliary lenses used to change prime focal length as a system only used on inexpensive cameras with none interchangeable lenses. However, Beck and others promoted such concepts in the late 1800s and early 1900s with their lenses that had elements which could be removed to make useable lenses of differing focal lengths.