Re: [ATM] Pretoria eyepiece

["Peter John Smith" <pjifl@bigpond.com.au>]

Gianluca,

The Dilworth extreme field design is represented by US patent no 4720183
It is very complex - too complex to be practical - not sure if one was ever
made.

The US patent office online records are an invaluable tool.  It is well worth
becoming familiar with them.  This resource is free.

see  this as a starting point  http://patft.uspto.gov/netahtml/srchnum.htm

Once you start with more recent patents, they reference previous ones so one
builds up a related set of designs.

I have never seem specific details of the Pretoria.  In fact, there are many
Eyepieces going under more common names which I have never been able to properly
pin down.  Another is the Galoc.  They are not represented in the US patents.

If you dig up any design details for eyepieces from other sources which are not
in the US pat records, I am VERY interested.

Yes, Eyepiece design has undergone a revolution.  It is now relatively easy.
But they still all have to be crafted to high standards and the more complex
ones become impractical to make.  Also, any really complex eyepiece needs
antireflection coatings on every air glass surface - preferably a multicoating -
or they are worse than simpler designs.

Peter Smith.



_______________________________________________
ATM mailing list http://www.atmlist.net/