Single mirrored Dobsonian Telescopes

This telescope is built around a 33 cm f/4.8 mirror, made by Jan van Gastel, equiped with ServoCAT and Argo Navis. (Jan van Gastel Mirrors). This is an example a Dobsonian telescope with almost perfect optics. The mirror has an excellent 0.987 Strehl ratio (click here for an optical report). This is almost perfect and it is no wonder that it provides very sharp star images.

As with all Dobsonian telescopes I make, they consist of three large pieces. This makes them easy to set up and to break down.

At the other end of the spectrum, this is a telescope build around a 18 inch f/4.8 Mike Lockwood mirror.

Or with a 20-inch f/4.0 Orion Optics mirror set....

The latest large Dobsonian telescope I built is around a 18 inch f/3.9 mirror. Originally this was one of the two 18 inch f/4.8 Mike Lockwood mirrors in the 2 x 18 inch binoscope (also in the above shown Dobsonian telescope). After I disassembled this binoscope, Jan van Gastel refigured one of the binoscope mirrors to f/3.9. (Jan van Gastel Mirrors).

Also this mirror has an excellent 0.96 Strehl ratio (click here for an optical report). This warrants very nice and crisp star images! The fast mirror has a lightpath of 177 cm, and the focusser is therefore almost at eye level.

With wheelbarrow handles the telescope can be moved easily to and from a shed where it is stored.

And -alas- the lightshroud is an essential part in my light polluted backyard!

Different Dobsonian Telescopes

Over the years I have experimented with different designs, as shown below.

Like this one, built around a 16 inch f/4.5 Orion Optics mirror set. Bob Hogeveen is currently the owner of this telescope.

click here for larger picture

Occasionally a different design presents itself, such as in the telescope below, which is built around an 8 inch f/6.0 mirror, made by Jan van Gastel (Jan van Gastel Mirrors). This smaller telescope is very stable and is very nice to view the moon.

Or one that is suited for traveling, compact and easily fitting in a travel bag.

In yet another different style I have also built these telescopes below. The left telescope harbors a 16 inch f/4.5 and the right telescope a 13 inch f/5.0 mirror.

I prefer secondary mirror cages that consist of two rings instead of one. For instance, they provide extra sturdiness and protection for the secondary mirror. Crucial baffling is also easy with this type of secondary mirror cage I place as much as possible inside the mirrorbox. The battery for the fans and the optional Argo Navis and/or ServoCAT are placed inside the mirrorbox. The mirror cells are made from solid aluminium. Together with how I link the trusses, the system is extremely rigid and this results in stable collimation. That is, not only over the range from Zenit to below, but also during the entire observation session. The trusses are linked together with small trusses. These are tightened inside the mirrorbox, completely out of sight.