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Old 11-04-2021, 08:43 AM
glend (Glen)
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Join Date: Jun 2013
Location: Lake Macquarie
Posts: 7,033
This is potentially a big subject, but keeping it simple: You do get greater magnification at long focal length, bearing in mind that with imaging there is no eye piece to boost it, you are stuck with the scopes native focal length. Longer focal length also means narrower field of view, and the trend for some years has certainly been for wide field, fast, imaging ( where time starved imagers can at least produce something). It is common for reducer corrector to be used with long focal length, which gives you some improvement in speed but usually these devices are limited to f ratio reductions of (0.6x at best, many at around 0.8x). Long focal length imaging usually means much more data acquisition time, which also means good tracking, guiding, - basically very experienced people who know their stuff. My advice (on the assumption you are just starting out imaging) would be to start out with fast short focal length wide field imaging of larger target or field objects. Take your time to learn the craft, skills, processing, etc before diving into longer focal length.
Of course your equipment needs to match your targets, and importantly the camera pixel size/image scale in relation to your scope, etc is crucial. There are plenty of online tutorials to read. This is a simple answer to your question.
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