| This Astro-Tech 2” prime focus adapter allows unvignetted prime focus photography with most 35mm and DSLR cameras having removable lenses that use a standard T-ring to connect to a camera adapter. It also can be used with most CCD cameras having a removable nosepiece that can be unthreaded to expose a female T-thread. It will not work with digital cameras having integral non-removable zoom lenses.
The adapter can be used with most refractors and Newtonian reflectors that are equipped with a 2” focuser, as well as with Astro-Tech Ritchey-Chrétien reflectors.
The camera end of the Astro-Tech adapter is equipped with a standard 42mm male T-thread for connection to a T-ring or the female T-thread on a CCD camera body. The barrel on the opposite end slips into a 2” focuser and is threaded to accept 48mm filters. The adapter is machined of aluminum, anodized black. The interior of the adapter has anti-reflection threading along its entire length.
A shallow safety groove is machined into the barrel of the adapter. This groove engages the thumbscrew or compression ring of your focuser to prevent the adapter and your camera from falling should the focuser thumbscrew accidentally loosen during use.
The prime focus adapter barrel extends 35mm into the focuser drawtube to provide a secure tilt-free installation when the focuser thumbscrew is firmly tightened. This keeps the adapter perpendicular to the focal plane for accurate focus over entire negative or CCD chip. This adapter adds 40mm of extension to the light path when the adapter is seated firmly into your focuser. The overall length of the adapter is 75mm, with 35mm extending into your focuser and 40mm of external light path extension.
This Astro-Tech Prime focus adapter needs an optional T-ring if it is not threaded directly into the T-threads of a CCD camera body. | 
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