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Octagon DT250-5 250mm f5
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Introducing the Octagon Fast Truss Dobsonian, made in the UK.

Based around the well known 1935 Serrurier Truss design structure, we have lightened and stiffened the OTA and utilised aerospace grade materials such as Titanium plate and Carbon-Fibre profiles for the trusses for maximum performance.

From 250mm to 610mm aperture, we have sourced the best mirror optics from all over the world and can have custom made mirrors with a myriad of coatings to your exacting specification. You can also supply your own optics and we can build your telescope for you. Optional Shott® Zerodur® Ceramic Mirrors can reduce the mass by up to 65% making it possible for a truly portable large aperture which folds down to the size of a small suitcase.

The fibre-glass resin case design is being finalised, and since it's made by a custom car enthusiast, expect some thrilling finishes. Milky-Way Metal-flake is the first one we're getting made!!!

Like other OTA's in the Octagon family, we offer an RC/Newtonian version of our innovative Zero7Gee focuser or you can select from a choice of branded focuser options. Also, there will be a range of accessories for helping you get the most from your astro-imaging for these fast Newtonians. Longer OTA's are now being developed for our Dobsonian range, based around our FTN platform, and those could be used as a high definition planetary imager.

Our own 18 point mirror cell design, features a sculptured dual fan ducted cooling cooling array, and up top a built-in heater for the secondary mirror as standard. Magnetic covers for both mirrors protect the optics when not in use, and there is an optional Armadillo cover to eliminate any stray light externally. 

The popular Dobsonian's are represented in the standard 10" (250mm) 12" (300mm) and 16" (400mm) size, and we are already looking towards producing larger OTA's up to 24". What we have done is put the collimation on top of the primary mirror cradle, making it much easier to align the mirrors. Our previous expertise with modifying other fast Newtonian mirror cells, means collimation should be a doddle! The secondary mirror is also easy to fine tune using an Allen key.

Like our other Octagon products, we are rolling out an exciting spectrum of colour combinations for the OTA's from the plates, the focuser bodies, even down to the Carbon Fibre pattern themselves! This is one highly configurable Dobsonian!

Each telescope made truly is a personal statement. You can even have your name etched into the OTA. (optional)

Each Telescope will come with a serial number, a unique Telescope Build Identification Number (TBIN) and a Logbook.

The will be an upgrade program for mirrors as well as a re-coating service.

A DT400-59 prototype is currently under construction for testing in early 2016

To find out more and to register your interest to update you regularly on how this new and exciting APO refractor range is progressing either call Dave Woods on 023 9257 0283 or via e-mail at dave@darkframe.co.uk


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Product Code
- DT250F4
Product Condition
- New
- Octagon Telescopes


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  • Contact Us
    11 Drift Road, Clanfield, Waterlooville, Hampshire, PO80JJ, United Kingdom
    +44 23 9257 0283
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