|
Don't get too carried away with the carbon fibre tube. Theres a reason why the high end APO makers don't use CF. CF doesn't contract when it cools down, which is great for minimising focus shift in a SCT, but in a refractor the glass in your lens also contracts changing the focus point, and with an aluminium tube the changing focus point is negated mostly by the contracting tube. CF in a refractor may look good and be lighter, but it won't perform better.
For purely imaging, a tak FSQ-85 would be nice, it will give you a large flat imaging circle of 60mm which will easily cover a 35mm DSLR chip or a large CCD chip. For a non-petzvel scope, you need to factor in a focal reducer/field flattener into the price, and you will usually not get an as large imaging circle, particularly if you are using a 2" reducer/corrector. So think about what size chip you are going to image on.
|