Equipment used

The possibility of seeing a substantial fraction of the objects in Arp’s Atlas only arose when I bought a third-hand 20-inch Newtonian in 2011. The project got under way properly in autumn 2014.  The telescope was made by Beacon Hill Telescopes of Cleethorpes. A plywood and biro plaque records first light in November 2005 and says it is 20-inch f4.5.

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Since buying it in 2011 I have:

  • Discovered that the mirror is a 50cm (close enough to 20-inches) but f4.13, so much shorter focus than stated.
  • Had the aluminium coatings on both mirrors refreshed by Vacuum Coatings Ltd. (The mirrors spent the first six years of their life with no covers at all).
  • Fitted a Moonlite 2-speed Crayford style focuser – essential given the wafer thin focal plane that goes with a f4.1 mirror (Photo 5).
  • Fitted a Telrad and erect image right-angle finder.
  • Fitted dew heaters for the Telrad, finder, secondary mirror and eyepiece (Photo 6).
  • Fitted digital setting circles (Photo 4). The declination encoder is connected using model boat propeller shaft universal joints (Photos 2 & 3).
  • Decorated the tube panels in fetching red marine vinyl and white lettering.

Eyepieces.  I have a full set of Clavé Plossls and 17mm and 8mm Tele-Vue Ethos eyepieces.  Experience has shown the Ethos do come very close to, or match, the light transmission of the exceptional Clavé oculars. The Arp galaxies are generally tiny and faint, so need magnification at the top end of the scale. If I was using a driven telescope then the Clavés would be fine. However, on this un-driven telescope the huge field of the Ethos swing it in their favour. They are simply easier and more relaxing to use.