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As every amateur well knows, one of the requirements a camera should have to be easily connected to a telescope is to have a removable lens.
As this is a common feature in those cameras that use classic film, this is not the case with digital cameras: just a few have removable lenses and those few that have them, have ... astronomical prices!
In my case it wasn’t about a camera, but about a camcorder.
There was no problem in visualizing the image, because it could be seen through the liquid crystal display. But how could it be coupled to the telescope?
Not being able to remove the lens from the camcorder, the eyepiece had to be kept in the telescope, bearing these consequences:
Longer tube assembly
Difficulty in centering the optics
I had to be creative and had the idea of putting a 2x teleconverter in place of the eyepiece in the telescope, transforming the telescope into an afocal system.
The result was surprising
Shorter tube assembly
Brilliant and contrast rich images.
But there still was the mechanical problem to be solved.
The camcorder, although small, was too heavy and the filter-ring not strong enough to bear its weight.
I then decided to build a clamp, made of duralumin, 1.5 mm thick.
The camera is coupled to the telescope in such a way that the clamp is trapped between the teleconverter and the adapter.
The strength this system has is surprising:
not only a camera to scope, but also a scope to camera coupling are possible!
In my case, the here called "telescope" is in fact a homemade multi-purpose 50 mm scope, with a focal length of 400 mm, that serves as a finder, as a guidescope and as a telephoto lens with magnificent characteristics (best contrast, lack of aberrations, no vignetting, pin-point star images).
Have a look at the image of Eta Carinae obtained with this lens, on Kodak TP-2415 Hypered with 30 min. exposure, with its diameter reduced to 38 millimeters through a light pollution filter. The Moon was 9 days old in this occasion, and it is possible that the moonlight might have contributed to reduce the reciprocity failure ("pre-flash effect").
Look also at the Mars
image, obtained with the same camera,
coupled, in this case, to a Meade 8 inch LX-200, in presence of notable turbulence.
a more comfortable focusing, I used a bellows. Besides, the tube length can be varied adding or eliminating one of those tubes used for macrophotography.
To be able to focus using cameras with no removable lenses, it is often necessary to reduce the length of the tube.
This operation cannot be done with commercial lenses, unless one dares to disassemble and modify them, which I once did with excellent results, coupling a Pentax lens to a Nikon camera. But it is quite dangerous and not advisable...
db - oct.2005 HOME