I have Bresser AR102s 4" 600mm f5.9 achromatic refractor. Excellent scope! However, going through my log it seems my zoom EP is mostly used mostly between 12-8mm. Would it be a worth upgrade to swap it for either 1000mm or even 1350mm version of the same scope? What would I loose and what would I get?
Short AR102s vs long AR102 or AR102L
Posted 21 April 2019 - 01:48 PM
You would gain better color correction with the longer scope vs. the shorter one, however, you would loose the wide field capability of the shorter scope. If your primary interest is lunar/planetary and double stars, the longer scope would be the best suited for this purpose. You can still do deep sky with the longer focal length scope but you won't be able to get as wide a field of view as with the F5.9. You could always obtain some wide angle eyepieces later on to compensate and get a little wider field of view in the longer scope however. The best all around solution IMO is to keep the F5.9 AND get the longer Bresser and that way, you'll have two scopes for each different application, deepsky and planetary work. If this doesn't work for you, then I'd just get a couple of wide angle eyepieces and go with the longer Bresser. Incidentally, I have a Bresser AR90L and have no trouble observing deep sky objects with it and a 24-8mm zoom eyepiece so it can be done. Also, the longer scope will allow you to reach higher magnifications easier because of the reduced false color which is more pronounced in the shorter achromat. You also won't have to use very short focal length eyepieces in the longer refractor to achieve those higher magnifications and that will save you some money because well corrected eyepieces are a must for short refractors and are generally more expensive. An F5.9 refractor isn't super short but will be more demanding on eyepieces that are of simpler designs, hence the need for eyepieces with more complex and expensive designs to get the best views possible, especially at the edges of the field of view.
Edited by barbie, 21 April 2019 - 02:03 PM.
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