I relay this question from Rete list in the hope that someone may be
able to speak to the optical arrangement of this terrestrial telescope.
Brian Whatcott Altus OK
-------- Original Message --------
Subject: [rete] ribright telescope
Date: Sun, 30 Jun 2013 03:57:58 +0000
From: Norman Heckenberg <heckenberg@physics.uq.edu.au>
Reply-To: rete@maillist.ox.ac.uk
To: rete@maillist.ox.ac.uk <rete@maillist.ox.ac.uk>
I know there are some telescope enthusiasts on the list and I hope you can help me to get a better understanding of a recent acquisition.
It's a late eighteenth century telescope signed Ribright & Son, London.
I have put some photographs and measurements on our new website at
It is missing at least two lenses, but still has more than my basic understanding of telescope optics requires. I have found references to '3 lens erectors' and '4 lens erectors' but have not been able to find any explanation of the design principles. Can anyone explain how these worked, or point me to a reference?
Also, there is a negative (flint?) lens present at the objective end, but it is in the mount 'the wrong way around' by my understanding of how achromatic lenses were usually assembled.
Finally, would the eyepiece lens have been a doublet, or is correction achieved through the combination of the other lenses?
Thanks for any assistance you can give,
Norman
PS I can do some ray tracing using Zeemax if I know what the general configuration was supposed to be.
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