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Old Monday 27th November 2017, 10:59   #51
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Join Date: May 2012
Location: Sheffield
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Originally Posted by adhoc View Post
Thanks everyone. The question now is, what exactly is hidden within that mysterious "1x30" in the superb diagram conveyed by Henry, or in the 60 or 70 "layers"*? Is it in principle only what Lee has explained or are there other layers for different purpose/s?

Also I would very much like to see a video of any coating/s being applied to a lens or prism but all the relevant videos I have yet found on the internet (all or nearly all on YouTube) on the making of binoculars skip showing this! Thanks for any tip-off here.

*all of different composition, or some materal/s applied more than once in succession
I have been told that the most common material used for the coating is magnesium fluoride and despositing it in many layers of different thicknesses allows it to deal with the unwanted reflection of a wide band of light frequencies/colours. Each thickness cancelling the reflection of a quite narrow band of light frequency. The only other coating that has been mentioned to me by folks who do this work is the final layer on the outside surface of the lens which nowadays is typically a 'water-repellent' coating that also is easier to clean.

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