ARCHIVE May2008
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Re: balancing an OTA
Art Morton wrote: > BTW > > ~ I look at ~25lbs as the upper limit for the G-11 for one piece of > glass, add temperature, power supply wind, cables, finder, […]
Astro knowledge / Long Exposure Photography / Optics
Astrophotography: The "best" focal length
Astrophotography has a lot of legends and rumors floating around as regards focal length of scope. Since the focal length of the scope, size of the CCD, weight of the rig, and […]
Re: rough calculation of spider weight
Jimbo S. Harris wrote: > Hello, > > I’m trying to get a rough idea of where the balance point of my OTA is > going to lie. Can you give me […]
Trixie design sessions – rough calculation of spider weight
Protostar wrote back about the spider weight, so I can continue to put data into the balance spreadsheet. Can you give me a rough idea of how much a 15.5” spider and […]
balancing an OTA
A, You gotta love seesaws. My 27# of mirror and mounting plates sitting 8” behind the top of the mirror box is not enough weight to balance the 6# of spider and […]
Not getting a lot of stars in before The Blessed Event
I am ashamed to admit that I’ve more or less given up on astrophotography this month. The spring galaxies are getting away from me again, and I hate to think about a […]
Trixie design sessions – rough calculation of spider weight
I needed to figure out how much the spider will weigh, so I sent an email to Protostar with questions. I’m trying to get a rough idea of where the balance point […]
Wooden Tube Clamps
Hi, This is the type of object that I was considering: http://pw2.netcom.com/~ahighe/ClampForms.jpg This is a pic from this page: http://pw2.netcom.com/~ahighe/17_5ultra.html Here’s a good photo of 2 of the clamps in action: http://pw2.netcom.com/~ahighe/MirrorBoxRear.jpg […]
Trixie build – cutting the ring blanks
This was the first weekend of several spent building out Trixie, the 13.1” scope. I decided to build the major wood pieces out of 1/2” Birch Ply and 1/2” Red Oak Ply. […]
Trixie's secondary
I asked the seller of Trixie’s mirror to send the original spider for the secondary, so I could use it on my test rig. Now that I’m looking at the object, I’m […]
RECENT UPDATE
Polar Alignment Calculations
Here’s a page that derives Polar Alignment Calculations. (update 5/2020: the original site is gone, so I found the text on Wayback and am inserting it below. This is by the original […]
Gear / Observatory / Telescope
Special Guest Star takes the mount at Hilltop O
The Astro Jedi needed somewhere to store his light sab—- I mean, bucket, and I was only too happy to accommodate him. I have decided that I need to come to a […]
General / Maintenance / Observatory
Dome shutter is motorized again!
I finally decided to bite the bullet and fix the shutter motor. Things went sideways last winter, and I’ve been opening the shutter manually (and tying it shut with rope, so we […]
Trixie 2017 – tube mods
I finally got around to cutting the MTA-UTA tubes to length; the only eyepiece that would come to focus with the focuser spacer in place is the Televue 55mm Plossl. If I […]
MOST COMMENTED
Observatory
Observatory 2.0 – Time has come today!
General / Maintenance
First Light, a deeper look
Mount / Observatory / Telescope
Observatory 2.0 – Result!
Observatory
Observatory 2.0 – The Pier goes in
Gear / General / Maintenance
Martin Farmer Wormblock installation notes
Deep Sky / Long Exposure Photography
NGC2244, The Rosette Nebula
Deep Sky / Long Exposure Photography
Another beautiful night.