16 inch f/5 Alt-Azimuth Telescope
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406 mm (16 inch) f/5 Computer Controlled Alt-Azimuth Telescope

February 26, 2008: a new 16" mirror from Mike Lockwood arrives!

This mirror is only 1.4" thick instead of the original 2" which makes it about 4 kg (9 lbs) lighter. I had anticipated this change from the outset by making the telescope bottom-heavy and using a 1 kg weight on the upper cage. Now the counterweight is no longer required and in total the telescope has become 5 kg lighter.

At my request, Mike made the FL slightly shorter at 2000 mm instead of the original 2040 mm so that I can reuse the truss poles - just need to cut them slightly shorter. In fact the mirror is now f/4.9 instead of f/5. The first two observing sessions showed that the quality of the mirror is excellent.

Together with the new mirror, I also decided to upgrade the focuser (replacing the 1990 Tectron R&P focuser by a JMI Ev-1) and the secondary mirror. The slightly shorter focal length and higher focuser meant that the 2.6" secondary was rather underdimensioned. I'm now long past the folly of going to extremes to minimize the secondary and decided on a comfortable 3.1" minor axis (still only 19% central obstruction). The 3.1" Antares Optics 1/30 wave secondary mirror arrived a week after order, and has now been installed.

The text and pictures below are for the old configuration, so this whole page requires an update. But first let's have some observing fun with it!

Below some pictures of my 406 mm (16") f/5 telescope.
The telescope is very compact and portable, weight of the parts is as follows:
  • Base: 7.5 kg
  • Mirror box: 24.5 kg (including 13 kg mirror)
  • Aluminum tubes: 3 kg
  • Upper cage: 2 kg
Optics are from Galaxy Optics, 1990. The scope is driven by Mel Bartels stepper motor system.

The assembled scope, ready for use:
The assembly starts like this:
First the altitude trunion is deployed:
Then the truss tubes and the upper cage are mounted:
The finder, light shield and counter-weights are added, and the laptop is connected. The electronics, batteries and cabling are kept in the gray box:
Close-up of the upper cage, with finder and light shield:
A view inside the mirror box by daylight and with flash, just to show the blackness of the mirror box interior:
The 18-point mirror cell with cable sling. The mirror sits very comfortably on 18 cork patches:
The mirror is supported laterally by a steel cable, attached to the upper side of the mirror box:
The scope can be stored and transported in a very compact way. The upper cage fits very nicely under the folded altitude trunion:
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