For many years I have been using refractors for imaging (I could afford it, before retirement !). I finally had to admit that to achieve good results, only high end refractors will do the job, i. e. those using top quality glasses - triplets or more. Naturally, they are very expensive, especially if you want a Pezval type refractor, with four, five or six lenses. And it gets worse if you need a long focal length, which comes with a rather "slow" speed, f/ 5.6, 6.5 or 7.
That is why I am using now only newtonian telescope. In fact they are beautifully simple instruments - a tube, two mirrors -, which means that the light does not have to go through multiple lenses, except for a field flattener. They can be fast, down to f: 2.8, and the collimation with a laser beam is fast and easy, and is usually quite stable for weeks, unless you move the telescope to another place.
The comparison is simple for an astrophotographer who does not have much money: a Pezval refractor with a focale lengh of 1000mm or more will cost over 10'000 euros. The equivalent in the newtonian range will cost between 400 and 1000 euros !
Now I am using three Sky Watcher newtonians and one TS Photon, a 150/f4 in my remote location in Spain, and here at home a 130mm/f5, a Quattro 200mm/f4, and a 200 200mm/f5.
And I am quite happy with them !
Philippe
That is why I am using now only newtonian telescope. In fact they are beautifully simple instruments - a tube, two mirrors -, which means that the light does not have to go through multiple lenses, except for a field flattener. They can be fast, down to f: 2.8, and the collimation with a laser beam is fast and easy, and is usually quite stable for weeks, unless you move the telescope to another place.
The comparison is simple for an astrophotographer who does not have much money: a Pezval refractor with a focale lengh of 1000mm or more will cost over 10'000 euros. The equivalent in the newtonian range will cost between 400 and 1000 euros !
Now I am using three Sky Watcher newtonians and one TS Photon, a 150/f4 in my remote location in Spain, and here at home a 130mm/f5, a Quattro 200mm/f4, and a 200 200mm/f5.
And I am quite happy with them !
Philippe
