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Re: (meteorobs) ALL SKY LENS
Probably the highest quality solution is to buy a fish-eye lens. For a
35mm camera, these can give a circular image (F=8mm) or a full-frame with
a 180 degree diagonal (F=16mm). Alternatively, a 16mm fish-eye can be
adapted to a 120 roll film back to give a circular all-sky image on 6x4.5.
Other fish-eyes of F=24mm, 30mm, 35mm or 37mm are available and can be
adapted to sheet film.
The 8mm fish-eyes are not commonly seen second hand and are expensive new.
I know of Olympus and Nikon at f/2.8, but there is also a Canon 7.5mm at
f/5.6. Nikon also have a 6mm fish-eye, but there is no point of greater
that 180 degrees, unless you observe from the summit of Mauna Kea.
16mm (or occasionally 15mm) fish-eyes are quite common second hand.
Nikon, Canon, Minolta are all good. A Russian 16mm fish-eye is very
cheap, and although not the same quality is excellent value for money.
The Russian 30mm fish-eyes for 6x6 cameras (Kiev or Pentacon mount) are of
exceptional value for their price.
Keep well clear of wide angle adaptors. They vary greatly in quality and
are generally very poor.
Compared to the effort of making a convex mirror all-sky camera, I think
the fish-eye lens wins hands down.
Cheers, Rob
Robert H. McNaught
rmn@aaocbn.aaodot gov.au
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