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Re: 6" Refractor?

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Posted by Dennis Simmons/">Dennis Simmons on March 30, 1998 22:42:09 UTC

: : : I have an old Leitz Wetzlar projection lens designed : : for an episcope. It is f/6,3 6" and consists of four : : elements mounted in a heavy steel cell. I have tested : : it very briefly and was impressed of it's light gathering : : power. Without any suitable mount, I could not check it : : properly. : : Has anyone some hints for a design; baffles,tube etc? : : Thanks in advance. : : :-) arne

Arne, I have a 6" f/8 Wray lens from a WWII reconaissance camera. It too is mounted in a substantial cell and has an iris which stops down to f/22. A guy in the UK fitted it to a tube with a 2" rack & pinion focuser. The system is good for prime focus photography but produces a blue halo around bright stars. Nebula & galaxies are okay. At around x150 mag the image begins to soften on the moon & planets. If I stop down to f/11 there is some improvement. I also have a Vixen ED102S 102mm f/9 refractor and the images from this are vastly superior to the Wray. However, I would recommend that you pursue this project and mount the lens, you will get hours and hours of enjoyment. : : Arne, I have a similar lens that was used for aerial l recon. of enemy during WW11. This too has a 4 element lens and works at F6.3. After I goteach lens polished and AR coated, I had the lens made up into an RFT refractor. While this gave crisp views of the Milky Way, the lens stills suffer from chromatic abberation. : It now has been converted back into a phot lens for 4x5-inch format and because the ray tracing of the light path was done for the refractor design, you will have to do this regardless what you use the lens for. : Well baffled and constructed, your Letiz lens will give you far better images than my old Aero Ektar! : You may have to use a light to medium Yellow filter to help combat some C/abberation. A heavy lens they are, so a solid Alt/Az mount is called for.

: As for a tube, get a local metal turner to machine some : Alum. thick wall tubing. and attach 2.7" Astro Physics focuser. You will be able to use then, a Pentax 6x7cm medium format, or larger camera. 35mm will be toooo easy! Good luck Arne, let us know how you got on, : Regards from Down Under JIM.

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