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Prototype Sky-Watcher Evolux ED Refractors

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Spinal Tap ?

This photo is doing the rounds on social media. Apparently it shows two prototype ED doublet refractors, a 62 and 82mm, that will sit somewhere between Sky-Watcher's Evostar ED doublets and Esprit tri

Waiting patiently for a 200mm... Or should that be 202mm 😜

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On 08/10/2019 at 20:48, Davey-T said:

Where did the fashion for odd size objectives come from 61, 71, 62, 72, 73, 82 etc etc, does it really make any difference to the view ?


yeah i have been pondering that

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3 hours ago, Earl said:

yeah i have been pondering that

Most of the time its just different lens cell designes causing the clear aperture to vary a little from scope to scope. It can be imperial to metric conversion. It can be to optomise the number of blanks you get out of a batch of glass. If a polilshing machine often leaves turned edges you will often make the lens elements slightly larger so that the turned edge can be hidden by the edge of the cell, perhapse more cost effective than buying a better machine and trying to get better polish right to the edge of the lens.

I would not worry over think it.


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  • 2 months later...
On 16/02/2021 at 10:46, Earl said:

yeah i have been pondering that

I think Nigel Tufnel moved into telescope manufacture...

  • Haha 2
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