When I stayed in Hamburg (in DESY's hostel) I decided for myself that not all nights need to take place down-town Hamburg, but maybe also on the DESY site, which has some surprisingly dark places. So, a telescope (which is not too big) is needed. When graduating in astrophysics there was no need for anything, and anyway, the research I did in that phase was more a computer based one. Not having observed as an amateur for years, I just wanted something to restart with, especially since my task to this time war clearly shifted to instrumentation in particle physics.
So, a nice day, I got myself a 114mm short tube Newtonian on an EQ2 mount. To that certainly one of the better “cheap” choices. The primary mirror is spherical, thus needs correction. This correction is done by a lens which is built into the focuser. My understanding of the optics of this telescope is that the primary mirror has a focal length of 500mm with the corrector lens acting as some sort of Barlow-lens lengthen the allover focal length to 900mm. The telescope allows for 1.25” eyepieces, it came with an adapter for use with the smaller diameter eyepieces supplied with the scope.
EQ2s to this time were delivered with nice wooden tripod legs. Very very nice indeed! My impression is that wooden tripods smooth out vibrations much better than tripods made of aluminium. No further issues on this EQ2 to be reported. .
The telescope was nice for serving my re-entry to visual (amateur) astronomy. But that's about it... I had some nice looks around in the sky, spent nice times relaxing from the (day-)job. Most of the time using the 20mm Kellner (other EPs suplied: 12mm Kellner, 6mm Kellner and a 2x Barlow) to just browse the around. Yes, I had fun with the scope!
Collimation? The construction of the scope makes it very susceptible to misalignment during transports. The collimation (regularly needed) is very very very tricky. The guilty part appears to be the corrector built in the focuser. Remove it and collumation of the remaining system is easy, but... the corrector needs to go back into the setup.... I believe that collimation (including everything) “on the star” is easiest... In any case collimation is very fiddly.
On the internet documents could be found concerning the removal of the “Barlow”. I am not quiet sure what this could serve. Aberrations will be worse (remember, spherical mirror) and focus will be much harder to be obtained. In focal condition, the focuser will be retracted almost completely, causing an enormous obstruction in the light path to the primary mirror.... My verdict: Forget about removing the corrector! If you own a scope of this kind, just enjoy what it is capable to... maybe with 1.25” Eps.
I would not buy the telescope again, not because I am disappointed, nowadays I known a little more about amateur-telescopes and would rather go for a richfield refractor.
Last modified Feb. 28th 2005