I started astronomy more than ten years ago, stopped about five years ago because … well life, and picked up the hobby again recently. I had sold my first telescope back then, and had to go through the process of getting another one. Here’s how I did it this time.
Defining the requirements
First, I wanted more aperture, so at least 150mm. The last telescope I had was great for planets and the moon, so I wanted something that could allow decent deep sky views. With my binoculars, I discovered that I love rich field views, so I needed something with a decent maximum true field of view, at least 2°, but at the same time, I still love watching planets, so I needed something capable of high magnification, at least 200x.
I now have something that I didn’t last time: a car. That’s probably the best upgrade you can get for your astronomy sessions, especially if, like me, you’re mostly a visual observer. But it’s a somewhat small car, and the whole gear set had to completely fit in the trunk, since I wanted to bring people along. That implied a tube length shorter than a meter, bag included. Getting all this right was very hard to do, and a bit of a gamble.
I was also curious about equatorial mounts, but I really didn’t want to have to deal with a broken motorized mount, so it had to be usable manually and possibly later upgraded with motors. Also, I wanted as little shake as possible, so I wanted the total load weight to be well below the mount capacity. The main problem here is that, as load capacity increases, it becomes hard to find manual mounts.
Last but not least, I wear glasses and wanted a somewhat comfortable experience at the eyepiece, and a set of exit pupils appropriate for the full range of objects you can find in the sky, so down from 5mm at most, until 0.5mm.
What didn’t work
These requirements excluded practically everything. Cassegrain telescopes generally have too high a focal ratio for wide field views. Achromat refractors are generally bad for planets and the moon. Apochromatic refractors become very expensive beyond 100mm of aperture. Dobsonians come closer to fulfilling the requirements, but if the focal length is too long, that reduces the maximum true field of view. They’re also bulky and not great for high power views, unless you get one with GoTo, which quickly gets expensive.
What did
The best fit I could find was a fast Newtonian with a manual equatorial mount. I got the Sky-Watcher Explorer 150P 150/750 OTA, which is an old f/5 Newtonian that Sky-Watcher seldom sells nowadays, because people are much more into imaging and prefer faster reflectors or small refractors. I did not dare get a faster reflector because I strongly dislike coma, and I also wanted to keep a decent focal length for high power views. As for the mount, I got the well known Sky-Watcher EQ5, a clone of the Vixen Great Polaris, both classic manual german equatorial mounts, with a load capacity of around 10kg.
For the eyepieces, I got the Explore Scientific 68° 24mm, and the Baader Morpheus 14mm and 9mm, along with the Omegon Premium 2x Barlow and the TeleVue 2.5x Powermate focal extenders. At first, I had the Explore Scientific 68° 2″ 28mm eyepiece, but that’s when I discovered that a 5.6mm exit pupil was too large for me, except at very dark sites, so I ended up getting the 24mm for general usage, and I use the 28mm when I go far away. There’s a bit of overlap there, but I got them at a decent price, and they provide roughly 2° (24mm) and 2.5° (28mm) of true field of view, just amazing to look through. Note that all these eyepieces have glass-friendly eye relief.
After a few months, I upgraded the focuser, and then the secondary mirror holder, got decent at collimation, and I’ve had the most memorable experiences since. Coma is indeed an issue, but I can live with it for now, and I have plans to deal with it later.
The unexpected reward
And on August 12, I drove down to Spain for the eclipse, and then spent the night with a dark sky blessed by the Perseids peak, an experience that will remain in a special place in my mind for the rest of my life.
