If I decide to upgrade, I'll think I'll go with the f/5 version. There is less of a central obstruction with the f/5 than the f/4.5. An f/4 has too much coma and is harder to collimate. The image size is a little bigger with the f/5 version. And the Paracorr is not necessary. For Dave Kriege, the f/5 is a "no brainer". I'm thinking about purchasing a trailer first before upgrading. I want to be able to view with my refractor and my reflector plus have room for sleeping bags and such. The Kolob Reservoir site is about an hour and twenty minutes from my house so I think it is wiser to sleep up there until morning. Debbie ps missed you up at Wolf Creek Pass. It was very cool and confortable up there. I may just head up there next month
[Original Message] From: David L Bennett <dlbennett@mac.com> To: <utah-astronomy@mailman.xmission.com>; Association Utah <uvaa@mailman.xmission.com> Date: 8/30/2004 10:08:30 AM Subject: [Utah-astronomy] f/4 or f/5? Why not try...
Why not go for a 16" f/16.5? See the mirror being offered at:
http://cgi.ebay.com/ws/ eBayISAPI.dll?ViewItem&category=31745&item=5917131317&rd=1
Brent Watson can attest to the benefits of observing from 20 feet off of the ground. The seeing is always steadier from such heights. Those with vertigo will stay away so lines for your scope will be shorter. You can get away with a very small secondary obstruction too and collimation is a cinch. No need for the correction of Naglers or a Paracorr either. Of course you need a flatbed to transport both the tube, counterweight, and extension ladder.
Remember, look with both eyes for best effect when viewing a first quarter moon from a dozen steps up the ladder. Those purple crescents make for a great trip!
dlb
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