The Best First Telescope?
I built this rig to be able to use my 50,100,200mm camera lenses from my Canon DSLR with an Atik CCD camera. The main part to mate the lens to CCD camera is the orange Geoptic Canon – T2 adaptor. This is a very neat device with an inbuilt thread to take 1.25” filters. I have an Astronomik HA filter which should give some nice mono images. The filters are a fiddle to change so I made a little tool for the job which makes life much easier.
The base plate is a piece of aluminium with various holes and slots to take the different lenses and focus motor. This has been bolted to a dovetail bar for easy mounting.
Using a camera lens on a ccd gives a very narrow depth of focus, so a fine adjustment is required. It isn’t easy by hand so I made the motor drive.
The motor I used is a small geared robotics motor with a 10 RPM output. I machined a shaft to fit a cog from an old printer used a toothed drive belt from the same defunct machine. This grips the lens focus ring on the lens and allows remote focussing. The motor mount is a piece of angle aluminium drilled to suit. Slots have been machined in the base plate to allow the motor to slide and tension the belt with a thumb screw underneath to lock in place.
I plug this into a cable running from the warm room to the scope so I can focus via the screen, no need to touch the lens to focus.
On newer lenses the aperture is set electronically from a DSLR so will remain wide open when attached to a ccd. I believe there is a work round but a front aperture mask is easy to make cut from some thin plastic. The better alternative is to use step down rings, a full set is cheap on ebay. Also if you use the lens you will get 8 pointed stars but a front mask will give nice round ones. It could be a feature you like but on something like the Pliedes I wouldn’t like it.
I have managed to use the set up and quite pleased with initial results. Below is a selection of a few images that have been taken with this setup. You can click on them to enlarge. As you can see, the quality of images from this setup is very high, and the setup itself is very portable.
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Hi David, I have used this means as have no other contact details. The P900 was £340 at E Global.
Best wishes,
Henry.