It’s a common mistake often made by first-time telescope buyers. Before you buy that big light-bucket Newtonian, ask yourself: will my mount hold such a beast? And what, exactly do I want to use the telescope for?
The mount is often overlooked in favor on aperture, but the stability (or lack thereof) of your mount will be the source of 90% of the happiness (or frustration) you’ll experience when using a new telescope.
A Mountain of Mounts
The primary aim of a mount is to hold the telescope steady, while accurately pointing it at a target in the sky. Mounts have two rotating axes, and follow two coordinate systems: alt/az (altitude and azimuth) or an RA/Dec equatorial mount (right ascension and declination, celestial sky coordinates analogous to terrestrial latitude and longitude). Both have trade-offs: an alt/az mount is simple to use and set up, while equatorial mounts, while they require polar alignment and balancing, will also track the sky.
Alt/az mounts can also be further broken down into lightweight tripod mounts or heavier Dobsonian mounts. Dobsonians are squat with a low center of gravity and simply rotate on a ‘lazy susan’ pivot. Dobsonian mounts are also great for large Newtonian telescopes, and simple to use for causal observing.
Likewise, equatorial mounts are either forked or German t-mounts with fork mounts being sturdier for large telescopes. A German equatorial mount, while compact, is also somewhat counter-intuitive to use, and must be weight balanced every time it’s set up. Plus, a German equatorial user always has to be ready to perform a ‘meridian flip’ along the right ascension axis as an object tracks along the north-to-south center-line of the sky.
Which brings us to the main question: What are you going to use the telescope for? If you’re happy observing with a small refractor, a light-weight tripod is suitable: if all you want is the biggest aperture you can afford, a Dobsonian mount is the best bet. If, however, you’re planning on doing photography, you’ll need an equatorial tracking mount, or a computerized alt/az mount capable of tracking along both axes simultaneously.
A Traveling Telescope Dilemma
We were recently confronted with such a quandary, while planning to travel to Spain and Morocco (this was pre-2020 pandemic). We wanted a complete telescope rig that was able to fit inside airline carry-on luggage and met international regulations. The telescope was a simple pick: an Orion 5-inch Maksutov offered a compact telescope, with a generous aperture. But the choice of a mount sent me on a quest for advice from seasoned observers across social media, and digging through reviews and forum messages on Cloudy Nights. Would this dovetail fit that clamp? Is it left or right sided? What’s the weight limit for that mount?
Fortunately the time-honored mantra of ‘simple works’ holds true for telescope mounts. Ultimately, I settled on an Explore Scientific Twilight II mount: It’s sturdy, simple, and has easily to use fine-guider axis controls. While it suits its purpose, I can see some improvements: For example, the tripod legs are double-pinned (good for stability), but I wish it had three-segmented legs instead of the longer two. Of course, while I then wouldn’t need to check the tripod due to its length, this would also cut down on stability.
You can see that every feature on a telescope mount presents a benefit-versus-liability trade-off. Telescopes and mounts are like automobiles, in that there isn’t really one universal choice that does it all: my small Fiat 500, for example, gets great gas mileage and is great for scooting around a dense urban area… but I would never take it off-roading, or use it to pick up lumber at the hardware store.
Here’s a quick test that’s easy to perform: aim your telescope at a planet or a star, give the tube a light whack with your hand, and look through the eyepiece: does the view settle down after about 3 seconds? If so, the mount holding the telescope is reasonably solid; if not, you’ve got a wobbly mount with legs of spaghetti that will jitter uncontrollably with the slightest bit of wind or nearby footsteps.
When is too much mount simply too much? Is such a thing even possible? Perhaps not, but I’ve seen many observers go in the exact opposite direction towards overkill, with tiny refractors perched on enormous, concrete-anchored mounts.
Don’t overlook the mount on your next telescope purchase. It could mean the difference between frustration and a steady night’s worth of observing.