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Re: [ATM] ATM: simplest ever unobstructed scope

To David Harbour :
   
  I was reading somewhere,I cannot quote the source,that the Herschel's was tilting the eyepiece to compensate for astigmatism.Most of the eyepieces used by Wilhelm Herschel was singlet plano-convex or biconvex lenses,so ''tilting the eyepiece done a long way toward compensating astigmatism'' (who i don't remember,maybe Gunther Buttman ?).John Pierce was still recomending singlet lens eyepieces  80 years ago ,isn't?Last year I done some experimenting with an eyepiece made of a biconvex lens having a focus of 15mm ,stopped down to about 40% of aperture,used on a normal small Newtonian.The image was so bright and it had such an optical  ''flavour'',that one of my projects is to make three such eyepices ,of  40mm,25mm and 15 mm.(But I'm writing all of this to you  in confidence,please don't unveil this to any of the ATM guys because,living the days of Naglers and Panoptics, they will take me to the shrink ,using that special shirt ...).
  Enjoy some Herscheliana,especially the eyepieces made by Johann Alexander Herschel, at the link below:
   
  http://www.nmm.ac.uk/collections/explore/object.cfm?ID=AST0844
   
   
  Regards,Mircea



''R-101

P.S. How did the Herschels ever cure the astig. and coma, that they must 
have had in horrendous amounts, in their big scopes? Does anyone know? There 
are some interesting "legends" about the Herschels- ''


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