Friday, February 19, 2021

Junk Scopes: Meade Infinity 60mm & 70mm

In this article, I'm going to talk about two more junk scopes being sold under a major brand name. Though I am pointing out bad scopes in this post and the last, I want to be clear that there are good telescopes for beginners and youth on the market. I will be highlighting some of those in other articles. They cost a bit more. But they are worth it, because scopes sold for under $100 (U.S.) have to make compromises that ruin their ability to view the night sky. Even under $200-300, there are going to be compromises, but they aren't always going to be deadly ones that ruin the scope.
The scopes I brand as "Junk Scopes" are just junk. They don't just make compromises, they're basically unusable without a superhuman effort. They destroy an interest in science, rather than nurture it. The companies that sell them should be embarrassed to have their name on them.

Today, we're looking at two scopes on the dreaded "Yoke Mount." Back in the 1960s and 1970s, many small telescopes were sold with this terrible mount. Later, we saw improved designs for beginner scopes begin to displace this design, such as the small Dobsonian, fork mounts, and pan-tilt heads with workable slow motion controls. My first and second telescopes had terrible yoke mounts. I fought the mounts far more than I ever looked at anything in the sky with those telescopes. When I was a teenager, I modified them to make them somewhat usable, but they were never good mounts. Here's a closer look at the yoke mount on the Meade Infinity 60 and 70mm telescopes:

There are three fatal flaws to the yoke mount:
  • You can't lock it on the thing you're looking at.
  • You can't keep it on the thing you're looking at.
  • You can't move it smoothly.

  • Notice the silver bar that goes across from the mount to the tube of the telescope. That was a 1970s addition to try to make the yoke mount usable without actually fixing it. You can't balance a telescope that's screwed directly to its mount. Which means it's going to slip off its subject. The locking mechanism on a yoke mount (friction from a thumbscrew) isn't strong enough to hold a scope up that is the least bit unbalanced, so they put this locking bar on to try to give it more strength to hold the scope. Spoiler: It doesn't work.

    The scope will still slide off target, the bar will get scarred from the lockscrew making it rough and bumpy, making the movement of the scope in altitude (up and down) even worse than it already is.
    And it's already bad because of the trunnions (the "ears") that sit in the fork. They and the fork aren't shaped right for each other. It can sit there, but when you try to move it up and down the friction varies, meaning it has favorite places to rest and places it just won't stay put at. Which means you can't point your telescope at the thing you want to look at. Even something as big as the Moon. It won't do it.

    The central shaft under the fork, on top of the tripod, is part of why you can't use this scope. Notice that lock screw? When you try to use it, it will shift the entire scope by pressing against the support for the fork above. It will only move it a fraction of an inch. But that little move right there will throw the telescope off into an entirely different part of the sky. If you don't use the lock, the scope will move too easily, again, throwing it off into a completely different part of the sky. You lose either way.

    The upshot is, if you see a yoke mount on a telescope, run away!

    Friday, February 12, 2021

    Junk Scopes: Celestron Astromaster AZ

    As I mentioned in an earlier article, the market has seen the return of junk telescopes in a big way. Even the big names were not immune to the lure of selling junk to unwitting beginners, and the Celestron Astromaster AZ telescopes is a huge example of that.

    These scopes are sold as astronomical telescopes, I mean, "Astromaster" and the AZ referring to Alt-Azimuth mount type for astronomy make that obvious. These are not being sold as "Sporting Optics" (though there is plenty of junk being sold as sporting optics, the bar to being useful is lower there.) These are being sold for astronomy, and they're sure to frustrate anyone who tries to use them that way.

    The mounts are basically cheap camera tripods and pan-tilt heads. They are OK for pointing a snapshot camera, or a pair of binoculars. But they are completely inadequate for pointing a telescope at something in the sky. Let's look at some numbers. Binoculars and cameras have a field of view that runs from around 20 degrees of angle to over 60 degrees for a typical consumer item. Cameras have the narrower field of view, binoculars are going to be 40 degrees on up. It's not hard to get something pointed to within that range.

    Telescopes have a field of view of about one degree, maybe a degree and half, at their widest (for a typical scope), and often even narrower! That means that to get your scope pointed at something, you have to grab that twisty handle on the tripod head, loosen it, move it to within 1/20th of an inch just to get something big like the Moon in the field of view! And then tighten it down without losing it! That's just over 1mm of accuracy! With your arm, while twisting a locking handle.

    That's nonsense, of course!

    Not only that, but the sky moves. By the time you get your scope lined up on something, it's already starting to walk out of the field of view. It takes the Moon two minutes to cross the distance of its own width. That sounds like plenty of time to get a look, but it goes fast. Most cheap telescopes don't give a good view at the edges of the field, so you want to look at things centered. And you want to look long enough to let your eye relax and soak up the details. All while messing around with a lousy mount that's about impossible to find something in.

    You want to have the ability to use a slow motion control, or have a mount like a Dobson mount that allows for easy adjustments to the scope as you view. These mounts don't do that. They also don't have an ability to balance the scope, so you not only have to fight that handle to within 1/20th of an inch, you have to deal with the fact that your scope is either nose-heavy or tail-heavy and it wants to slide off the subject.

    Don't get these things, for yourself or for anyone else.
    If you already have one, you should consider getting something else. You are punishing yourself unnecessarily if you're trying to use it for astronomy. If you have the short tube model, it's OK for a spotting scope. The long focal length models are less useful in that role, however.
    You can get wider field eyepieces. They'll make it easier to align on objects in the sky. And you can use them with a new telescope as well, so if you give up on your Astromaster AZ, the money isn't wasted.

    Tuesday, February 9, 2021

    Return of the Garbage Scopes

    It wasn't too long ago that the market for telescopes wasn't too bad. There were still garbage scopes being sold, but the general quality of telescopes being sold under brand names wasn't very bad. At least, they weren't selling scopes so bad that they should be treated as a violation of the customer's trust in their name.

    That time has come to an end.

    Lately I have finally had a chance to re-engage with beginning astronomers. I was "away" for a few years because I made a cross-country move. Now, I am back to being active in community astronomy. I am in a great astronomy club, I am working with beginners in selecting and using new telescopes, and looking forward to the end of the pandemic so that we can start doing things in groups in person again--right now it's practically all via Zoom or other virtual meetings.

    When I started looking at what is being offered at the low end of the price range, I will admit that I was shocked. Telescope designs that have no business being sold as astronomical telescopes are everywhere. They are being sold under brand names. They are being sold by what were formerly reputable dealers. There are dealers I used to send people to because I felt safe that those dealers wouldn't sell the people a piece of junk, who are now featuring absolute crap among their products. Not only has the garbage come back onto the market, much of what is being sold now is worse than the garbage that was being sold 30, 40, even 50 years ago.

    The junk is not even being confined to a single line.
    I can't tell someone "buy one of the Celestron XYZ scopes, they're all OK", or, "Meade's ABCs are all pretty good for the price." There are no safe product lines among the low end scopes.

    So, I have felt motivated to start posting to this blog again to try to combat the tsunami of garbage on the market. New astronomers are the most vulnerable to the disgusting and predatory sales practices that foist worthless, unusable junk upon them. Their interest is honest, but their skills to use the tools of astronomy, and their ability to evaluate them, are very limited. They rely on things like brand names to let them know they're buying a decent product. They rely on product descriptions to tell them what an instrument is capable of. Current products, and the ad copy and "specifications" published for them are not just misleading, they pervert the very intent of having published specifications. They ignore the inadequacies built into the telescopes being touted to pretend that they can achieve some abstract level of performance used for the published capabilities and specifications.

    I'm angry. And I'm going to call out their crap.

    Stay tuned. no vendor selling a scope under $500 U.S. unless you know enough that you don't need someone on the internet to tell you what works and what doesn't.