I just received my "slightly used" Bresser AR102S "Comet Hunter" (OTA
only) from Telescope Warehouse yesterday. The intent for purchasing this OTA
was to have a very portable (fit in a suitcase) and sizeable Grab & Go scope. This is an inexpensive OTA
, only $125.00. So my expectations were geared accordingly
It was boxed well enough but the ES
finder foot had the plastic retaining screws screwed in place and the screw heads were sheared off during shipping. I emailed Bill Vorce of Telescope Warehouse and the replacement screws are already in the mail. Really not that big a deal.
The Bresser AR102S Comet Edition is a 102mm f/
=459) rich-field refracting telescope. And as you can see from the photo, it’s not your normal refractor configuration. Instead of having the focuser aligned with the objective at the back end of the tube, the focuser is mounted on the side of the tube. Just like you would find in a Newtonian reflector because it uses a reflector-style secondary mirror* to bounce the light from the objective lens to the eyepiece. This makes for a very short, compact scope, and theoretically, should allow for easy collimation via that secondary mirror (I haven’t tried that yet). Scopes like this are sometimes called “reflactors” because they combine an objective lens with a secondary mirror.
is 20″ long and 4" in diameter and 4 1/4″ of the 20" length is dew shield. It weighs in at a reasonable 6.1 lbs. In the pictures, you can see there is a dovetail on one side of the OTA
, and there is a shoe for a finder (not included) on the other side of the OTA
. Having the dovetail on one side and the finder shoe on the other is convenient because it means the OTA
can’t roll over and bang the focuser if you set it down on a flat surface.
The focuser is a single-piece aluminum casting rack and pinion style which allows only 1.25" EPs. The focuser does have two features of note. First, it wraps tight to the 4″ diameter tube. Second, and more importantly, the focuser knobs point across the tube on this scope as opposed to down the length of the tube, this feature may prove to be a key feature once I start using this OTA
. Again, the focuser is a single chunk of aluminum (not plastic) – the 2″ tube (also aluminum) can’t be separated from the base, nor rotated relative to it. Additionally, the 1.25" EP
holder does unscrew (meaning it's threaded) so I'm looking for a way to use a 2" EP
adapter on this scope but since it is a dedicated 1.25" EP
scope, there is no adapter offered by Bresser or ES
I received no collimating instructions or users manual from the seller (no biggie). So I contacted Explore Scientific and they promptly emailed the collimating instructions and the users manual.
As usual, since receiving this new scope, there is not a star to be found so I'm still waiting to perform the first light. But the daytime use shows a crisp image edge to edge. I think the contrast could be better but I'll wait on that judgment. Additionally, I've read that this scope has no baffles and would greatly benefit by flocking the inside of the OTA
. I'm looking at material for that right now. As far as the first light -- standby,...
* Existential telescope question: is it still a secondary mirror if there’s no primary?