Why I don't like G.E.M.s
At some point I'll do a proper "what telescope should I get?" post (the short answer is, a 6" to 10" Dobsonian reflector and the long answer is DM me or wait for the post.) But I wanna just do a sorta P.S.A. here...
Do NOT buy a beginner telescope with a German Equatorial Mount.
TL;DR: In the beginner price range, the mounts are undersized and flimsy and they are frustrating and convoluted to use. A good altitude-azimuth mount or Dobsonian rocker-box is preferable if you're starting out.
I have used several GEMs over the years, both high quality and cheap, and even a few in between.
Now there's nothing wrong with a well made German Equatorial Mount, and in fact if you want to get into serious astrophotography a well made G.E.M. is almost a must-have. But decent computerized GEMs suitable for astrophotography start at about $1000, well above the beginner price range.
Ok so what's a German Equatorial Mount?
I'm gonna pick on the Celestron PowerSeeker 127EQ here, because it is the poster child for truly terrible telescopes:
The 127EQ combines horrible optics, horrible quality control, horrible accessories, and an undersized mount that is mediocre even at the best of times. Don't buy it for any price unless you are prepared to put some serious work and money into it to make it usable. But beware: there are plenty of other telescopes like it, even by otherwise reputable brands.
Looking at the mount--the section between the tripod and the optical tube (the telescope itself), this can be a little confusing. Basically the core idea behind this is that the mount will track stars against the rotation of the Earth using a single axis. This sounds like a huge advantage. Twist a single knob and you can keep a star, deep sky object, planet, or the moon in the field of view easily.
I'm here to tell you from experience, it's not worth it. The ease of tracking with a single knob are not worth all the trials and tribulations a GEM will put you through. It goes like this.
In order to use a GEM correctly, it has to be aligned. The angled axis is set to an altitude equal to your latitude, and then pointed either north or south depending upon your hemisphere, with the goal being to point the telescope directly at the celestial pole (and Polaris in the northern hemisphere).
If you do not polar-align the mount, it will be working against you at all times. Resist the temptation to pick the whole tripod up and move it when looking at different parts of the sky.
To set the mount up, you first balance the telescope tube back and forth in its tube rings, then you balance the counterweight on the declination shaft. You take it outside, set the latitude setting on the RA axis equal to your latitude on the Earth's surface, and point the mount as close to north (or south) as you can get it.
To move the telescope, you loosen the R.A. (celestial longitude) axis and the Dec (celestial latitude) axis clutch knobs, move the telescope where you want it to go, then tighten the clutch knobs so that you can fine-tune the aiming with the slow motion cables--those knobs on long stalks sticking out at odd angles.
A GEM can reach any position in the sky, but in actual use several problems pop up. In a lot of beginner models in particular, the slow motion cables will run into eachother, and you've either got to take them off and back on, or approach from the other direction. Some manual GEMs use low profile knobs instead of cables and I wish more did this.
In the dark, and while trying to look through the eyepiece, you're always feeling around kinda blindly trying to find the clutch knobs and the correct slow motion cable.
Then if you're using a refractor, you'll have to rotate the star diagonal so the eyepiece doesn't point downward or off to some weird angle. It's worse if you're using a Newtonian reflector, where the eyepiece is on the side of the telescope tube. In that case, if the eyepiece ends up in some weird orientation, you have got to loosen the tube rings, rotate the tube within the rings, and tighten it down, all without changing the balance of the Dec axis. And if your finderscope and eyepiece are heavy enough you might even have to adjust the counterweight on the shaft to balance in Right Ascension.
And all of this assumes that the mount is a well made manual EQ mount that is working as intended--something like the Celestron CG4, or the Exos Nano EQ3.
In the beginner telescope market, the mount won't be well made. It will be undersized, cheap, and with terrible quality control. The biggest problem is the R.A. polar axis. There's a lot of slop in the bearing, so that when you move the telescope up to point at an object, you're bending the bearing. When you finally find the object, and let go of the telescope, you'll find that the object just disappears, because the bearing un-bends. So you've got to constantly account for that extra slop, get in vaguely close with manual aiming, and fine tune with the slow motion cables.
Often you'll find your balance wasn't quite perfect, maybe because you changed accessories or rotated the tube in the rings. The object will start to drift out of the field of view, even as you try to use the slow motion knobs to keep it steady.
But there's also the shaking. Undersized flimsy mounts and tripods with telescopes far too large for them are the expectation in the beginner telescope market. A telescope will magnify every shake or bump.
Every single movement of the telescope is accompanied by a whole procedure where you've got to babysit the mount. But when you finally do have an object in the eyepiece, and you're able to track with one axis, that's surely got to be better than the alternative, right?
Eh. Honestly no. Like, yes, it is easy to track an object once you've found it (assuming nothing else is going wrong). But let's look at the comparable procedure of finding and tracking an object in a well-made altitude-azimuth (up/down and left/right) mount, such as in an affordable Dobsonian.
You take the telescope outside. You plop it down whereever. You put an eyepiece in. You sight through the finder and point at any object you can see. You just push the optical tube to wherever it is you want to go, and it stays there.
I think EQ mount users imagine that an altaz is like an EQ, where you kinda have to take things one axis at a time. Not so. In a good altaz you can easily make diagonal movements, and the mount itself almost seems to disappear.
So now you've found an object. Uh oh! You bumped the telescope a little, and the object's gone. No slow motions to reel it back in... no matter. Simply grab the tube, and gently nudge it by 'pulling the sky' where you want it to go.
Now you've zoomed in at high power and the object is moving through the field of view as the Earth rotates. Uh oh! It's moved out of the view. No slow motions to track it. Of course, some altaz mounts actually do have slow motions, you just have to use two axes to track. But more realistically, any time the object reaches the edge of the field of view... you just nudge the scope. A gentle nudge will send the object to the other side of the field of view where it can drift across the middle again.
At the kinds of magnification that are realistically attainable in a beginner-grade telescope, an object will not rush through the eyepiece so quickly that you need to nudge it constantly. You have plenty of time to observe the object before you have to nudge it.
And most of your observation will be done with low-to-medium magnification where the motion of Earth's rotation is extremely subtle. When observing deep sky objects, the mount just disappears. You hop from star to star to find the faint object that was invisible to the unaided eye, and see a star cluster or a dying star or a star factory nebula or a galaxy. If you want to go to the other side of the sky, all you gotta do is move your chair. No fiddling with clutches and knobs and tube rings. It's just you, your telescope, and the universe.
Alright, so say you already have a cheap GEM. What can you do about it?
I would say you should at least try using it as a genuine GEM for a night or two and see how you like it. Your mileage may vary. If you use the GEM correctly, even a poor quality one, you will still have a better experience than the average beginner who misuses the mount. But you will probably find the limitations of this. What you can do in that case is to take the polar axis, which is normally angled equal to your latitude, and set it pointing straight up (as if you were standing on the North Pole).
That essentially turns the instrument into a weird kind of altitude-azimuth mount. It takes some of the stress off the right ascension (now azimuth) bearing, and makes the balance along the counterweight shaft a lot less critical. It makes the motions of the mount less counterintuitive. And it means that you don't have to rotate the tube within the rings in order to keep the eyepiece upright.
Some people also take the counterweight shaft off, but your mileage may vary on that.
A cheap GEM converted into an altaz like this might actually perform better than some of the especially bad altaz 'fork-of-doom' mounts and photo-tripod style mounts that you sometimes see in beginner telescopes.
Now, there are really two levels to my analysis here and I don't want to muddy things too much. 1) Most EQ mounts on beginner telescopes are objectively bad. They are undersized, flimsy things with poor quality control and will frustrate you to no end even if you know how they work... and most beginners don't know how they work. If you have one of these scopes, by all means give it a try--but don't feel too discouraged if you can't make it work. 2) In my opinion, even a well made EQ mount is more frustrating and distracting to use than a Dobsonian or a well made alt-az mount. This is especially the case with a Newtonian reflector, but to a lesser extent still applies to refractors and Cassegrains.
I will not defend the GEM against number 1, but I will provide a bit of a defense for number 2 in the interest of fairness.
Plenty of amateur astronomers prefer manual german equatorial mounts to a Dobsonian.
Maybe they like focusing on the equipment more than the night sky, maybe they're just experienced enough that to them, the complex procedures involved in using a GEM really do melt away and they can focus on the sky.
Maybe they like to use setting circles to find objects rather than star-hops or computerization. Maybe they focus on Lunar/Planetary work at high magnifications where the ability to to track is more important.
But one way or another you do see plenty of amateur astronomers, particularly the more experienced ones, primarily using german equatorial mounts.
And a well made GEM mounted telescope in the home position, especially a refractor, does just look excellent, doesn't it...
And certainly these scopes will satisfy many experienced amateur astronomers, particularly collectors. Even knowing from experience how frustrating a GEM-mounted Newtonian is, I still salivate thinking of owning one of those really nice vintage ones.
But I don't think they are suitable for the beginner. I don't think a beginner should ever choose a telescope based on its aesthetics. You're buying a telescope to look at the night sky. Its performance on the night sky is what you should be focused on.
Also, an altaz mount has a fixed point at the top of the sky (zenith) making its motions kinda stall out around that area. It no longer becomes possible to do smooth diagonal motions and you end up taking long azimuthal slews just to move a few degrees. This phenomenon is "Dobson's Hole." In practice you just wait for the object to rotate out of the zenith. But with an EQ mount you can look at the zenith just as easily as any other part of the sky. But this is a trade-off that comes at the cost of the celestial pole becoming fixed. Far north objects become difficult to point to. (And unlike Dobson's hole they'll never leave the pole hole, but there's also only like. 2 objects that are in the pole hole worth looking at.)
But the real place where the German Equatorial Mount is useful, is astrophotography. Yes, manual EQ mounts can be fitted with clock drives for this purpose and that's what they did in the old days, but realistically you're going to need a purpose-built computerized mount. A good compact refractor or newtonian on a bulky computerized equatorial mount can do a lot of astrophotography. In fact for astrophotography the equatorial mount is the most important thing.
But at the end of the day, you're not gonna spend thousands of dollars on an astrophotography rig as your first telescope. Buy a tabletop dobsonian or a full size dobsonian. You'll be a lot happier.
