Quote:
Originally Posted by thegableguy
Has anyone gone in this direction, ie from reflector to refractor? Did you regret it? How much did you miss the focal length? Any major benefits?
... APO vs ACHRO.
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Chris...
First question is whether you are interested in wide field photography, or are a visual observer (i'm a visual observer, no AP whatsoever). For AP focal ratio is the first priority where "average" image quality over a wide field will do, but visual observations of close double stars, lunar & planetary - these are all about image quality (resolution) on-axis.
A few years ago I sold all my gear and, succumbing to a bout of refractoritis, I bought a TS 130mm f/7 triplet APO to see what all the fuss was about. A significant aspect in my case is that my first "real telescope" was a superb refractor - a Thomas Cooke 4.25" f/15 on a beautiful bronze clockwork mount. Not only a beautiful antique, but one that works superbly. The TS 130mm refractor was very nice, optically everything you would expect.
However... one night I did a side-by-side comparison with a C5 and an old-school 15cm f/8 newtonian. Sorry refactor guys, stop reading here. At the same magnification the refractor and the C5 were indistinguishable... it's true. However the refractor didn't fare so well compared to the 15cm Newtonian - which had perfect optics and slayed the refractor on Jupiter at high power.
A few months later a Skywatcher 180mm f/15 Mak was advertised here on IIS which was optically 9/10 and cost ⅓ the price of the refractor. Side-by-side with the 130mm refractor, the Mak killed it on every object, bar none. Bang-per-buck, the mak was a clear winner. Always.
At X2 per mm (260X) on double stars the refractor was good. On the trapezium in Orion, E and F stood out in the mak but the refractor struggled.
Ultimately, in 2016... an acquaintance in the US decided to part with a rare scope - a Santel MK91. I had met the owner and the scope many years ago and when he decided to sell it I leapt at it.. However not cheap and I sold all my gear - the refractor, SW Mak, mount and eyepieces to fund this, AND mount a new mount to put it on.
No regrets... optically this scope kills Questar 7's, 10" and 11" SCTs.
In retrospect IMHO the SW 180mm Maks are a bargain - optical quality appears to be consistently better than 20cm SCTs, and its a perfect size and weight for a portable scope.
Stepping up to a 9" or larger scope is problematic - the weight and focal length are both significant and pose challenges that may be beyond some owners.
As for a 9" refractor ... that is way beyond portable.