The Takahashi Epsilon 250 is an f3.4 telescope that uses a hyperbolic primary with a four-element corrector and flattener to produce a 70mm image circle on film that is 4.9 degrees across and flat to the edges. The instrument includes a 4-inch focuser with a focus lock that allows focus to be maintained throughout a photo session. A built-in camera angle adjuster allows 360 degree rotation of a camera body to allow better framing of a photo without loss of focus. The focal length of the telescope is 854mm.
When I lived in Houston, my permanent observatory housed the Takahashi Epsilon 250 telescope. The optical tube assembly was supported by a Takahashi NJP mount on a permanent pier sunk in concrete. Now that I live in Arizona, and do not yet have a permanent observatory, I occasionally take this scope out in the field and support it with an NJP mount on a tripod. The optical tube assembly weighs more than 70 pounds, and is not exactly the most portable scope that I own.
This telescope is primarily used for astrophotography or CCD imaging. I have a custom-made adapter for an ST-8E with a CFW-8 attached. The adapter is designed to provide the correct spacing between the corrector lense and the CCD chip. I also obtained a custom digital corrector lens for the telescope. I understand that only a handful of the digital corrector lenses were ever made. When used for film photography, a Takahashi 78mm refractor is used as a guidescope, and an ST-4 autoguider is employed to guide the main scope during long exposures. The above photo shows the FS-78 guidescope with the ST-4 attached.
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