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14" travel dob

12" travel dob

 

10" travel dob

8" travel dob

4.5" travel dob

4.5" f/4.0 at less than 1800 g

or: I used to be a Bresser Pluto ...

 

 

I built this Dob in 2004 for a backpacking trip with our children to Thailand. I allowed the setup to be a bit more complicated, my main concerns were compactness and weight. For a travel Dob, that will be carried around in the backpack for several weeks, the "costs" are measured in weight and volume. This telescope is extremely "cheap" at only 1800 g and compact 2.7 liters!

The optics of this travel scope belonged in former life a to one of those Pluto 4.5" f/4 sold under the label Bresser. Unfortunately, its mirror was not very well corrected and proofed to be still largely spherical in the Foucault test (well, it was cheap ). Decreasing the aperture to 10 cm (4") f/4.5 made a major improvement in image quality. Still far from being perfect, the mirror could be used at least with lower magnifications. In the meantime, I have fully parabolized the mirror. Due to the softness of the glass and the fast optics, this proofed to be not an easy task. 

The mirror rests on a small triangle of 2 mm alloy, the wooden parts are made of 4 and 6 mm plywood. The finder is a revolutionary new high-tech device, where I succeeded for the first time to eliminate any transmission  losses .

The thrilling painting in the background is one of the early pieces of a local artist here in Freiburg (before he turned to Realism and bought an SLR camera). It features the Orion Nebula. Unfortunately, the central part is a bit overexposed .

 

 

The poles can be collapsed to 29 cm. The upper poles are NOT made of carbon, even that it looks like it (which was not intended). Collimation works with push and pull bolts. It's not as convenient as it could be, but it yields an unbeatably low profile. 

 

 

 

The eyepiece and secondary plate are made of 2 mm aluminum with a fitting aluminum tube to serve as a sliding focuser.

 

 

 

The stray light shield is, again, not made of carbon (even that it looks like it) but of a high tech material, black cardboard, and is attached with a revolutionary click-and-go mechanism.

 

The total weight of the Dob, including three eyepieces, a red flashlight, and an UHC filter, is less than 1800 g. Everything except for the altitude bearings and the poles fits into the small mirror box. The total size of the package is 14.5 cm x 16.5 cm x 10.5 cm.

 

The small travel Dob traveling: here in Thailand.

Experienced observers will notice that the finder had been mounted on the wrong side of the telescope (well, I noticed that immediately later at night ...).

 

 

This little Dob is always in danger of catching a little dust for not being used that often (well, it was fun making it) and its little mirror often didn't see star light for a long time (and that's a cruel thing for a mirror). 

I therefore build a new tube for the mirror, using a new and unused (!) stove pipe, that happened to have the diameter I wanted. Together with a low profile focuser and a red dot finder, it's perfect for observing at home with the kids.

 

 

 

home

14" travel dob

12" travel dob

 

10" travel dob

8" travel dob

4.5" travel dob