Quote:
Originally Posted by g__day
Its a trade off isn't it? A refractors costs way more, has shorter focal lengths, less light reach but gives superb focus and tighter stars (someone please check that last point is true and explain technically why!). An SCT is lower cost, so at a same price point has much longer focal length, far more light reach, but even with optimal focus I presume its stars won't be as tight as the refractors?
Is it just a function primarily of focal length that makes an SCT's stars appear more bloated at optimal focus than a refractors? Put another way if you had say a ten inch apo refractor and a ten inch SCT both shoot the same star field onto the same camera (and you didn't expose over the CCDs well depth - so no blooming) - both perfectly focused and both with say a 2.5 metres focal length - would the refractors stars be the same size as the SCTs - slightly less or significantly small and tighter?
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I always thought it was due to the larger CO of SCT's, but I am probably totally wrong. Cant even remember where I heard that from
