Astigmatic binoculars

[KizmeRD]

I recently came across a passing reference to the usage of ‘astigmatic binoculars to make submarines more visible’ in a book discussing early anti U-boat measures. Does anyone know more about how these worked, and why they might have been better than using ordinary binoculars when searching for U-boats on the surface? I couldn’t find anything about this on the internet.

MB

[DavidOwen]

There would appear to be a school of thought that astigmatic conditions may increase contrast sensitivity - thus making it easier to detect a surface object?

Modern research appears to  debunk that when the astigmatic condition is binocular (both eyes) rather than monocular (single eye).

(PDF) Effects of astigmatic defocus on binocular contrast sensitivity (researchgate.net)

I haven't yet found anything specific to ww1 yet.

[DavidOwen]

Also, lower magnification gives better visibility in low light conditions Exit pupil | Basic Information about Binoculars | Nikon Consumer

[KizmeRD]

Thank you David, for verifying that there’s at least some logic and science behind the idea that astigmatic binoculars may have provided greater optical sensitivity in particular circumstances, so at least its conceivable that their use may have been trialed during WW1 as a possible tool for U-boat detection. I just need to discover some contemporary documentary evidence now that will confirm this.

MB

[DavidOwen]

You might want to try the Birdforum for further assistance About The British Military's Binoculars Used In Post War? | BirdForum (amazing how helpful bird watchers can be!)

[DavidOwen]

Another forum to explore is Cloudy Nights A Navy optical book, including binoculars repair - Binoculars - Cloudy Nights A question on there may well bring you the answers you seek (or it may appear blurred...)