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Skywatcher 80ED

This page is dedicated to the new acquisition, as of February 2005, of the Skywatcher 80ED.

Some of this is pure peer pressure : I already own a Vixen Short tube 80 which I use for guiding with a webcam. On the other had I wanted to see what an apochromat could do and really fancied some widefield digital photography. So I did two things : got the 80ED from Darkstar and bought a Direct Wide Adapter from Orion Optics. The Direct Wide Adapter is to mount on the Vixen VC200L to use that as the main long focus camera and use the ED80 as the fixed tube guidescope. The Vixen short tube 80 has a great two-axis kinematic mount pressing against springs. This allows a large degree of motion to pickup a guidestar. To achieve the same with the ED80 requires a set of three-point rings from ADM. Originally these were going to mount off the main VC200L tube. However in the end a large Al ( 400x300x8 mm) plate was cut and drilled with a dovetail plate on the back and suitable holes to mount the variety of 'scopes on the front.

The ED80 is a short tube refractor of 80mm aperture mounted in the a 102mm OD optical tube assembly, with a crayford focuser at one end and standard removable dewcap and pierced cover with sub-aperture cover at 50mm diameter. The telescope arrived in a long double packed cardboard box straight from the importer : Optical Vision Limited although purchased through dark Star. When retrievng it from the packaging, the lens cell had obviously taken a bang, as it was hanging visibly crooked and loose from the main tube, the lens interior was speckled with aluminium turnings from the tube threading for the lens and the three screws mounting the focuser at the other end had spalled paint fragments from the tube around the screws.

Putting the lens cell straight was an easy matter - take it off and re-thread it back on the tube. Images seem fine but no high-magnitde star tests have yet been performed. The focuser is smooth but still a bit sloppy like most other Skywatcher focusers I have used. ( I also own a 150mm f/6 Skywatcher refractor). The tension on the focuser is controlled by a thumb screw which bears down on a pad pressing on the tube roller in the Crayford focuser. I have it loaded up with a heavy 2" diagonal and a 2" 30mm eyepiece and it holds position OK.

To add a camera on to the backend of all this was either going to take using a 2" stub to a t-thread, allowing a camera to mount on a t-adapter. However, having invested in the Direct Wide Adapter which gives more throughput via a larger central aperture, why through it away with a t-adapter on the end ? So I made an adapter on the lathe. The adapter had to have a Skywatcher female M56 x 1.0mm thread to mount onto the end of the focuser tube. The other side had to be a female Vixen thread, which turns out to be a female M60 x 0.75mm. The added bonus of using the Vixen kit is that I also have the x0.6 Vixen focal reducer optics from the VC200L, so in theory I can now use that too.

The pictures below show how it all fits together.

Skywatcher 80ED with 2" Diagonal in the Skywatcher 2" focuser.

 

Skywatcher dellivered condition around focuser screws.

OM1 ( could be any other T-compatible camera such as a 300D ) mounted using the Vixen DWA adapter and 65mm long extension piece from the VC200L and Skywatcher-to-Vixen adapter.

The 2" focuser on the Skywatcher. the adapter threads on the M56 x 1.0 tube thread.

The dismantled OEM T-thread adapter for the OM-fit t-adapter. This splits into the bayonet fitting and the t-thread female part.

The Vixen Direct Wide Adapter and OM-adapter and Skywatcher turned adapter.

The Vixen Direct Wide Adapter and OM-adapter and Skywatcher turned adapter.