30+inch+F3



The links below detail the design and construction of the new 30 inch F3 Dobsonian Telescope that was started (18th April 2015). The test rig has now been tidied up and the mirror completed August 2015.

This telescope is a first prototype for Thomson Telescopes Limited and has been through a lot of research and development phases to get to this point. Development of the interferometer and techniques for making such a large and fast optic were very challenging. Verification of the surface to ensure that it was better than diffraction limited required many different tests to be undertaken. Tests included modifying the test rig for vertical testing with the interferometer using a large flat. Folding the telescope with a precision flat for on-sky testing (prior to making a new large flat. Future instruments will be available for commercial sale when all technical issues are resolved. Only a few minor technical issues are now outstanding to make the instrument easy to use and aesthetically pleasing. Another blank has arrived and ready for polishing. The first production instrument is expected to be available for sale late 2016.

There are manufacturers that produce large fast mirrors, but I am not aware that they make telescopes as fast as F3 at this size. The techniques developed in the making of this prototype are unique and significantly improve manufacturing times.

@http://www.thomsontelescopes.com/

Pages will be updated as development progresses.


 * Purchasing the mirror blank**


 * Grinding the back flat**


 * Grinding the front surface**


 * Polishing the front surface**


 * Figuring and Testing**


 * 30 inch F3 Secondary manufacture**


 * Telescope design**


 * Telescope tube and mount manufacture**


 * 30 inch F3 Test Rig**


 * 30 inch F3 Handling Equipment**

Images below are of the test rig telescope at Kelling Heath Star Party in September 2015. This was first light for the telescope with the optics recently coated at GalvOptics. It had a lot of interest and always a queue behind the eyepiece.





The secondary mirror is now completed and the image quality is fantastic!!! The image below is of Jupiter on the 21st March 2016. Images were taken at prime focus (no barlow) with NO tracking and only 8 frames stacked. QHY5-II-C was used. Not too bad considering. Visually there was a LOT more detail visible than in the images below. Shadings could be seen inside the red spot. I have never seen as much detail in any other instrument other than of Saturn through the Faulkes 2 telescope on Maui.