This project began with some doodles I did of Victorian telescopes. I sketched and sketched and increasingly began to wonder if such a thing could actually be built - and sometimes wondering can be a dangerous thing to do!
The Great Wetherell Refractor incorporates the riveted construction and engraved brass circles of many telescopes from the late nineteenth century, yet it’s also modern in it’s use of electronic controls and the best of today’s coated optics. It’s not a replica, but a modern working instrument grounded firmly in the tradition of the great Victorian refractors.
There is an unashamed element of romance in great refractors, even the term "great refractor" conjures up some of the awe and majesty these old instruments commanded in their day. Leading modern telescopes like Keck and Gemini are amazing science tools and infinitely more powerful than any refractor ever built, but they're not The Great Keck or The Great Gemini are they? :)
Here you can see the telescope doing its thing under the stars and also the eyepiece storage area behind the doors in the telescope pier.
The individual eyepieces sit in rotating holders so that by rotating the holder, you can easily access any of them
This is one of the concept sketches that lead to the creation of this telescope
This view shows the 200mm f9 oilspaced apochromatic triplet objective by Yuri Petrunin of TEC
The only way to achieve wide angle views with a scope this long is to have physically large eyepieces. This image shows a custom built 3" eyepiece and 3" diagonal next to standard 2" and 1.25" telescope accessories. The eyepiece has a focal length of 65mm and a field of view of about 70° giving a true field of view of around 2.5°. It attaches to the 3.5" feathertouch focuser via a 3" adaptor available from starlight instruments.
This is a close up of the "Victorian" remote control for the telescope. The design philosophy was to encapsulate as much of the look and feel of a traditional refractor as possible, but not to compromise its usefulness as a modern observing instrument. The centre switch engages the tracking drive (the speed of which can be adjusted using the knob). The other buttons are fast and slow drive up and down both RA and Dec.
Forget go-to, how about some good old fashioned Victorian Dial-to? Setting circles can work superbly well if (a) they're large enough to read to within a degree or so and (b) your polar alignment is spot on. The numbers on the RA circle are screwed on rather than being engraved directly into the brass so that it can be changed for Northern or Southern Hemisphere use.
The brass steering ring allows you to pull the telescope to a given point in the sky then fine adjustments can be made using the electronic drive
Here's a person for scale, an 8" refractor is actually quite a large beast. It looked nowhere near that big on my drawings, if it had I might have been scared off beginning the project.
Of course the whole point of any telescope is to look through it and here's an impression of the views it gives of the Moon, Jupiter, Saturn, Venus the Eta Carinae star and Antares.
I've also written a short article on Cloudy Nights describing my impressions of using this scope and comparing it to a smaller TEC 140.
Almost two years after the completion of the telescope I finally, finally got round to making the last part; the dew cap seen here. I don't have a major problem with dew but the main purpose of the cap is to give the scope the longer more "classic" look of the original concept drawing. And if it keeps the dew off too, then that's a bonus :)
Finally, please understand that the term "Great" is simply "a tongue in cheek" reference to the Victorian tradition. It's by no means the largest refractor ever built by an amateur astronomer, just the largest one ever built by me :) There's a whole Yahoo tech group (homemade refractors) devoted to folks who build refractors of all shapes and sizes. For another example of what other folks out there do, check out some of Rob Wiederrich's work here.
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