Amongst the finest scopes for imaging, this 1997 model comes with high quality Zerodur optics, almost unprocurable in new scopes. If you don't know anything about Zerodur (used in the Keck scopes) read this quote from wikepedia.
Zerodur has both an amorphous (vitreous) component and a crystalline component. Its most important properties[6] are:
- Low thermal expansion (≈0.2 × 10−7/K at 0 °C–50 °C) which is an order of magnitude better than that of fused quartz
- High 3D homogeneity with few inclusions, bubbles and internal stria - (as contrasted to Cer-Vit)
- Hardness similar to borosilicate glass so that it can be ground and polished more easily than fused quartz
- High affinity for coatings
- Low helium permeability
- Non-porous - (as contrasted to sintered ceramics)
- Good chemical stability similar to that of fused quartz
The scope features:
- Carbon fibre tube with Losmandy dovetail plates top an bottom
- F9 Zerodur mirror (2800mm focal length)
- Electronic secondary focussing with hand-set controller
- 70 mm fixed instrument adapter setup
- Low profile fans
- Internal flocking
- Manuals and original optical certificate
$11,500 now
$10,500(new $24,000) - all reasonable offers considered
You might wonder why such a low price for such an amazing scope, primarily because of the wear and tear on the tube and the fact that these days you can buy a GSO R/C for a lot less.
A couple of details:
You may want to realuminise the mirror. I realuminised 18 months ago and am still happy with its performance, you may feel different.
The tube shows some wear and has been patched and repainted white, so don't expect a concourse condition tube. That said, once focus has been set - it stays stable, not for hours but for days. That's the carbon fibre tube at work. Also, the bulk of the tube has been internal flocked.
I replaced the three external fans with 3 low profile internal fans, apart from looking nicer, it is also quieter. Fans are definitely recommended as a way of reducing tube currents.
The 70mm fixed instrument adapter setup works well but can be removed if you want to add a rack and pinion focusser.
Feel free to ask questions. Will also consider trade for mount.
Inspections welcome. I will ship at the buyers expense (will be expensive)
