From: David Davis 
To: frank{at}katestone.com.au, atm{at}shore.net
Reply-To: David Davis 


Sidgwick, (Amature Astronomer's Handbook), talks about it a bit on page 140 ...

"8.4.10 The Airy ocular: A development of the Huyghenian, but not a
notable improvement apart from a slight gain in spherical correction.  It
consists of a convergent meniscus field lens and a crossed biconvex eye
lens.  It has been reported to be usable at relative apatures where the
spherical aberration of an ordinary Huyghenian would be prohibitive."

The Huyghenian is a fairly simple eyepiece to make being comprised of two
elements.  I suppose if you could get a flint field lense and size the stop
right, it could be good eyepiece.  I don't know the design well enough to
go beyond that.  I know a criticism of the Huyghenian is that the image is
formed between the lenses which amplifies many of the defects.

David Davis
vorblesnak{at}yahoo.com

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