Thread: Prime focus??
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Old 30-10-2019, 04:37 AM
glend (Glen)
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Join Date: Jun 2013
Location: Lake Macquarie
Posts: 7,033
You need to know whether your scope is optimised for visual or imaging, and most new scopes advertise what sort of setup you are buying. Yes, visual optimised newts may require slight movement of the primary mirror location, and people can work this out, but imho it is preferable to purchase an imaging optimed scope as there is no "work" to do, and these scopes typically have imaging capable focusers ( which can handle the weight of the imaging train). Every scope has a back focus distance, one where the image falls on your camera sensor in focus. Many scopes require the use of spacer rings, used to adjust the precise distance required to achieve focus. Variable spacer rings are available, these use a locking ring to deliver precise distances. Spacer rings might screw into DSLR bayonet adaptors, via M42 or M48 threads, and provide a rigid imaging train.
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