|
Effective focal length has little to do with it when it comes to astronomy. The Borg at 390mm will have roughly double the magnification compared to your Canon 200mm.
For a given scope, "magnification" will be the same whether you use a small or large chip camera, but you'll see a wider field of view with a larger chip. The resulting image from a smaller chip camera might appear more zoomed in, but that's only because you've blown the image up larger to fill your screen/print vs the image from a larger chip.
If the math were correct, a longer focal length scope with a larger chip will give the same image as a shorter focal length scope with a small chip, but there will be less detail with the latter combination - eg. and FSQ-106 and ST-11000 might give a similar field of view to an FS-60 and a ST-8300, but the former will give a more detailed image through greater magnification.
Hope this helps!
DT
|