I am forming an e-mail list on the subject of binoculars ...

On the use of targets for collimation see Bureau of Naval Personnel, Basic Optics and Optical Instruments, pp. 170 and 200. As they note, such a technique is subject to weather (I got rained on) and not particularly convenient. I am still looking for the reference to the invention of collimators around the time of the first world war. ................
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