Jon Watson Astro
The Newt
This is the 14" I've been sloooowly putting together.
It's originally a ~2003 f4.6 Orion Optics (OO) Dobsonian.
I got OO to make an 'Ultra Grade' 1/10 PV f4 mirror, changing the focal length from 1600 to 1400mm. I cut about 170mm off the tube and repositioned the primary mirror.
I had a carbon fibre secondary spider made by TS optics in Germany (which cost more than I originally paid for the scope). I fitted the primary and secondary mirrors with Kendrick dew heaters. I also upgraded the focuser with a 2" Feathertouch. The focuser/secondary area is stiffened with a flocked aluminium sleeve, which also offsets the centre of balance, giving a slightly tighter turning circle. The final weight is 23kg.
It now has 100mm back focus, as my intention is to run the scope at f2.9 with a 0.73x reducer (TS or ASA). I think f2.9 may not be worth trying without upgrading to a carbon tube however. I also have a 5x Televue Powermate, which can take the focal ratio to f20, with a pixel resolution of <0.1" using a ZWO 290.
P.S. Ronseal does much more than what it says on the tin. I promise to buy some more genuine counterweights, just not this month.
The Newt
This is the 14" I've been sloooowly putting together.
It's originally a ~2003 f4.6 Orion Optics (OO) Dobsonian.
I got OO to make an 'Ultra Grade' 1/10 PV f4 mirror, changing the focal length from 1600 to 1400mm. I cut about 170mm off the tube and repositioned the primary mirror.
I had a carbon fibre secondary spider made by TS optics in Germany (which cost more than I originally paid for the scope). I fitted the primary and secondary mirrors with Kendrick dew heaters. I also upgraded the focuser with a 2" Feathertouch. The focuser/secondary area is stiffened with a flocked aluminium sleeve, which also offsets the centre of balance, giving a slightly tighter turning circle. The final weight is 23kg.
It now has 100mm back focus, as my intention is to run the scope at f2.9 with a 0.73x reducer (TS or ASA). I think f2.9 may not be worth trying without upgrading to a carbon tube however. I also have a 5x Televue Powermate, which can take the focal ratio to f20, with a pixel resolution of <0.1" using a ZWO 290.
P.S. Ronseal does much more than what it says on the tin. I promise to buy some more genuine counterweights, just not this month.