There is a new experimental refractor concept, it uses a very weak objective lens which is a single plano convex 100mm aperture imager of around F:40, this is not corrected for color, but if a small achromatic 7X50 binocular objective is placed half way along the focal length, the resultant F:6 image is very free of colour, the difference between the red and blue focus is only about 1mm, the color reduction is many more times than it should be, it can be reduced to 0.4mm by addition of a second lens. It is known as a "Wall Hypochromat", it is not a dialyte or a schup' as there is no flint lens in the system, the color is suppressed not corrected for. There is a little color left in the system and this can be ignored if you are not too fussy, it will make a superb RGB filter scope. The main thing it is very cheap, I have made a 5inch version.The system is in it's infancy and needs to be developed, how about it you ATM's out there. Ref to the Journal of The British Astronomical Association June 2009 vol 119 No3. Wanna know more, discuss it with me.
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119 No3. Wanna know more, discuss it with me.
