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DBL%20Hendrix%20small.png College chemistry, 1983

Derek Lowe The 2002 Model

Dbl%20new%20portrait%20B%26W.png After 10 years of blogging. . .

Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases. To contact Derek email him directly: derekb.lowe@gmail.com Twitter: Dereklowe

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December 12, 2013

Science Gifts: Telescopes, Etc.

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Posted by Derek

As longtime readers know, one of my spare-time occupations is amateur astronomy. I often get asked by friends and colleagues for telescope recommendations, so (just as I did last year), I'd like to provide some, along with some background on the whole topic..

The key thing to remember with a telescope is that other things being equal, aperture wins. More aperture means that you will be able to see more objects and more details. It's only fair to note that not all amateur astronomers agree with this, or about which kind of scope is best. As you'll see, larger apertures involve some compromises. And keep in mind that while a bigger scope can show you more, the best telescope is the one that you'll actually haul out and use. Overbuying has not been my problem, dang it all, but it has been known to happen. These days, eight-inch reflectors are a good solid entry point, but smaller ones will be cheaper (and perhaps worth it to see if this is something you really want to get into).

There, I've mentioned reflectors. Those are one of the three main kinds of scopes to consider: the other two are refractors, and folded-path. The refractors are the classic lens-in-the-front types. They can provide very nice views, especially of the planets and other brighter objects, and many planetary observers swear by them. But per inch of aperture, they're the most expensive, especially since for good views you have to spring for high-end optics to keep from having rainbow fringes around everything. I can't recommend a refractor for a first scope, for these reasons. A cheap one is not going to be a good one. That's especially true since a lot of the refractors you see for sale out there are nearly worthless - a casual buyer would be appalled at the price tag for a decent one. (Scroll down on that link to see what I mean). No large refractors have been built for astronomical research for nearly a hundred years.

That said, refractors have very, very devoted fans. If your vision is discerning enough, you'll enjoy the views through a really good one more than through any other kind of scope. But if you're just starting out, your vision is almost certainly not good enough yet (see below), so I continue to steer people away at first.

The next type, Reflectors are all variations on Isaac Newton's design: open tube at the top, mirror at the bottom, and an angled secondary mirror back near the top to reflect the light out to the eyepiece in the side. All modern large-aperture research telescopes are some variety of reflector. They provide the most aperture per dollar, especially with a simple Dobsonian mount (more on mounts below). One disadvantage compared to the other two types is that reflectors have to be aligned (collimated) when you first get them (and every so often afterwards) to make sure the mirrors are all working together. A badly collimated reflector will provide ugly views indeed, but it's at least easy to fix. It's also true that if the primary mirror is of poor quality, you're also in trouble, but the average these days is actually quite good, and this really isn't much of a problem any more.

Finally, the folded-path (catadioptric) types (Schmidt-Cassegrain and Maksutov designs, mostly) are a hybrid. They have mirror in the back, but also a thin corrector plate covering the front, which also has a small secondary mirror in the middle of it. The light path ends up coming out the back of the tube, through a hole in the primary mirror. Like refractors, these basically never have to be aligned. They're more expensive per aperture unit than reflectors, but a lot less than refractors. Their views are pretty good, although purists argue about how they compare to a reflector of equal size. (Refractor owners would probably win that argument, but they have to drop out at about the five or six-inch mark, when the other two telescope designs are just getting started). These designs are also compact (all that light folding), which makes the more portable and easier to mount.

And that brings up the next topic: what you do mount one of these fine optical tubes on, so you can use them to actually look at things? An equatorial or a fork mount will let you follow the motion of the objects in the sky easily, especially with a motor drive - the Earth's rotation is always sweeping things out of your view, otherwise. A decent mount of this kind will definitely add to your costs, though. The "Dobsonian" mount is a favorite of reflector owners, since it's quite simple and allows you to put more of your money into the optics. You do have to manually grab the telescope tube and move it, though, which takes some practice (and often some home-brew messing around with the mount). Some people don't mind this, others are driven nuts by it. You can put a motorized platform under a Dobsonian (my own setup) to motor-drive it, which some consider the best of both worlds. This is, though, suitable only for visual observing; a platform is almost never good enough for real astrophotography (see below for more).

On the topic of motorized telescope mounts, I should say something about "Go-to" models. These are not only motorized to track objects, they will slew the scope around to find them from a database or by manual entry. I'm very much of two minds on these. For an experienced observer, an astrophotographer, or a researcher, they can be an indispensable tool to spend more time observing and less time hunting around. For a total beginner, they can ease a lot of frustration when first learning the sky. But at the same time, they also can keep you from learning the sky at all, and they can very definitely encourage hopping around too quickly from one object to another. If you do that, you can "see" all sorts of stuff in one evening, while at the same time hardly seeing anything at all.

That's because visual observing is all about training yourself to see things. One thing every new telescope owner should know is that Very Little Ever Looks Like the Photographs. Especially since the photos are long exposures on wildly sensitive CCD chips, usually through big instruments, and under excellent conditions. Through the eyepiece, I am very sad to report, nebulae are not tapestries of red, pink, green, and purple: they range from greenish grey to bluish grey. And although with practice you'll pick up really surprising and beautiful amounts of detail in deep-sky objects, at first, everything can look like a blob. Or a smear. Or not appear to even be there at all, even when a practiced observer can see it right smack in the center of the eyepiece field. I really enjoy seeing these things with my own eyes, and trying to find out just how much detail I can pick out and how faint I can go, but it's not for everyone. This is one of the single biggest things that needs to be emphasize to anyone planning to buy a telescope. Even the planets need practice: you'd be surprised how small Saturn is in a budget eyepiece, although it's striking at almost any magnification. If conditions are bad, Mars and Jupiter can look like they're at the bottom of a pot of boiling water. And you need time and patience to see all the details there are to see on them.

Now, photography is another story. Astrophotography is an expensive word, although thanks to webcams and the like, getting into it is not quite as bad as it used to be. But for most purposes, you'll need one of those motorized mounts that'll track objects across the sky. That's very convenient for visual observing, too, naturally, but a really good one for long-exposure photography can cost more than the telescope itself! I'm not an astrophotographer myself, so I won't go into great detail, but if you want to try this part of the hobby, prepare to think about the telescope mount as much as you think about the optics. Imaging equipment ranges from simple webcams all the way up to wonderful stuff that easily costs as much as a new car, or perhaps a small house. And you'll also need to be prepared to learn a lot about digital post-processing. That's another thing that all those great astrophotos have in common: someone spent a lot of time working on them, after they spent a lot of time gathering the data in the first place.

So, what to buy? I've scattered some Amazon links in the above to representative scopes. In general, Meade and Celestron are the two brands you'll see the most, and if you stay away from their cheap refractors, you should be fine. And Orion also sells good stuff of their own brand, (on Amazon and from their own site). (Again, I'd stay away from inexpensive refractors there, too). Other good sources are Astronomics and Anacortes.

There are a lot of excellent resources for specific opinions on different models, and on telescopes in general, at Scopereviews. Cloudy Nights is also a huge resource, full of message boards on every amateur astronomy topic you can think of (and classified ads for used equipment as well). Rod Mollise has a lot of good stuff, if you can handle his folksy dialect style. For the truly hard-core visual observer, Alvin Huey at Faint Fuzzies is a great source for downloadable observing guides (many of them free). I use them, although there are plenty of objects in them that are outside my range (I use an 11-inch Dobsonian reflector). He has observing guides for sale, too, but every single thing in every one of them is outside my observing range. Dang it all. And I can recommend the free software Cartes du Ciel (Sky Charts) for printing out charts of your own.

Comments (22) + TrackBacks (0) | Category: Science Gifts


COMMENTS

1. PharmaHeretic on December 12, 2013 3:46 PM writes...

Currently Maksutov-Cassegrain designs provide the best combination of portability, price, handling and versatility for most amateurs. A decent 5 inch MC on a reasonably solid guided drive can be purchased for less than 1,000 USD and will last for decades.

Coupled with a cheap astro-grade CCD (200-400 USD) it can provide pretty decent pictures of the moon, planets and brighter deep sky objects. Also there is a lot of information on digital image processing using Photoshop or its Open source equivalents.

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2. starnewbie on December 12, 2013 4:02 PM writes...

I read this blog daily. You posted this wonderful synopsis of telescopes EXACTLY 24 hours after I purchased my first telescope; Dobsonian mount Orion 8XT1.

The coincidence is astronomical!

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3. Jason on December 12, 2013 4:02 PM writes...

Any comments on the Galileoscope?

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4. Douglas Triggs on December 12, 2013 4:46 PM writes...

I have to disagree pretty strongly with PharmaHeretic. One, unless you want to drive beginners away with frustration, there's no way I would ever suggest starting with astrophotography until you already have some experience under your belt.

And sure, a catadioptric scope is a good trade-off for portability versus size once you have some idea of what you're doing (my primary scope is a 9.25" SCT and was an 11" SCT before that), but it's a lousy scope for beginners (plus expensive for its size, albeit not as expensive as a high-end refractor), and Maks are the worst of the bunch due to their particularly narrow field (exactly the opposite of what you want when you're starting out).

When you're ready to start playing with Maks (or high-end refractors or light buckets or wherever your interests end up taking you), you'll know (and likely, you'll end up with more than one).

I might recommend that beginners get a newtonian scope, either a small-ish Dob (say 6-8" to keep it portable) or a 4-5" tube on a decent equatorial mount (for half or less the price of the Mak), but what I'd REALLY recommend is finding the local astronomy club and look through other people's scopes before you really start shopping. Not that people tend to take the advice, so just go online to Orion and get the basic 8" Dob and be done with it -- you'll end up joining the club anyway to figure out how to actually use it and have a much better idea what to get when you upgrade to your second scope. :)

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5. David Formerly Known as a Chemist on December 12, 2013 6:06 PM writes...

The one mistake a lot of people make is buying more scope than you need. I have an old TeleVue Pronto (70mm aperture refractor with superb optics) that I paid about $1200 for, about 15 years ago (!) that I still use. Sure it's small with low aperture, but it gives stunning views of the planets, clusters, etc. And as small as it is, it's still a pain in the butt getting it mounted, aligned, and finding what I want to look at, especially in a light-polluted urban environment. Unless you live way out in the country with very dark skies to enjoy, portability is essential! Especially when you live in the northern part of the country where it doesn't get dark until 9:30 in the summer and it's too brutally cold to observe in the winter (like I do).

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6. SF Bay assay guy on December 12, 2013 6:46 PM writes...

Some like the folded light path scopes like the Mak-Cass or Schmidt-Cass designs, but I'd argue that the longer focal lengths of folded light path scopes results in too much magnification for general use. Good for planet viewing, but not so great for some of the beautiful objects that require a larger field of view, like the Andromeda galaxy or Orion nebula.

I have several scopes, but my favorite is a humble 600mm ED refractor. I've had good luck with Orion products and customer service.

Click my name if you want to read an amateur's intro to astrophotography.

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7. SF Bay assay guy on December 12, 2013 7:44 PM writes...

BTW, when I say humble 600mm refractor, I'm talking about the focal length. It would be more correct for me to refer to it as an 80mm refractor (due to its 80mm aperature). But I do think focal length is as important a consideration as aperature, though it seems to get less attention.

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8. p on December 12, 2013 9:19 PM writes...

Whether you're seriously or casually interested, the SkySafari iPhone app is very good. The cheapest one if you're casual, more expensive the more serious you get.

Great write up, Derek. I've shared it with some folks who ask me similar questions.

I think it less important what type of scope you get, as long as it is decent, as long as you know it won't provide Hubble image type views and that it will take some effort to get going. Not herculean effort but it isn't watching TV, either.

Starnewbie (#2), you'll be very happy with the 8XT1.

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9. Dr. Manhattan on December 12, 2013 9:48 PM writes...

I bought a Meade 8 inch SCT a couple of years ago when my 6 inch Newtonian finally fell apart from use (and the misuse of incompatible metals in the spider assembly). I agree that Newtonians are the best starter scopes. I learned the sky with my first scope; the new SCT has a computer and GPS. It tracks nicely but I am glad that the first scope forced me to learn object locations.

I was going to get a 10 or 12 inch SC scope but the weight (I ain't getting any younger) factored in. My skies are dark (being slightly on the western side of 495, unlike Derek), but not as dark as eastern Connecticut's were.

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10. Anonymous BMS Researcher on December 13, 2013 12:25 AM writes...

I would suggest before getting a telescope, first learn your way around the skies with a good pair of binoculars. Spend a little while doing research online before you select binoculars for stargazing use: if you do not know what the phrases "light gathering" and "exit pupil" mean then you need to do more reading.

Remember, a medium-grade pair of 7x50 binoculars are much better than what Galileo used, and think what he discovered!

There are lots of good astronomy apps for computers, cellphones, and tablets; my personal favorite is Distant Suns which I first used under MS-DOS back when Bill Gates said "nobody will ever need more than 640K of RAM." Now I use the Android version on my tablet.

In the opposite direction, there are some very nice USB microscopes available, I've had fun with one of those. There again, it's good to start off with a hand lens before using a microscope.

Easier on middle-aged eyes than the compound microscope I had as a kid! It does mean they won't learn the skill of sketching what they see by looking through the scope with one eye and at a piece of paper with the other -- says this old fogey who remembers taking film from the microscope to the darkroom...

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11. pete on December 13, 2013 12:46 AM writes...

re: learning your way around the sky

I'd like to give a shout-out to the free, open-source app, "Stellarium" from www.stellarium.org

It brings a surprisingly sophisticated planetarium to your computer (mac, PC, linux, etc versions) and there's no telescope required.

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12. Carl "Bear" Bussjaeger on December 13, 2013 8:37 AM writes...

"photos are long exposures on wildly sensitive CCD chip"

In fact, the really colorful images people see online are typically false color composites assembled from multiple shots in several wavelengths, not all of which the human eye can see.

Probably most folks here know that, but I've been unpleasantly surprised at some of the people who expect to see the Pillars of Creation in full Hubblesque living color.

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13. Slurpy on December 13, 2013 9:40 AM writes...

Are we going to get another discussion of microscopes this year? I think I'm finally ready to pull the trigger on that. . .

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14. Ann on December 13, 2013 9:43 AM writes...

Really nice write up. Did a lot of my own research a few years ago to buy a scope for my husband. Like starenewbie, I ended up with an 8" Orion Dobsonian mount reflector. It's been a tremendous success and would highly recommend it to others.

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15. anon on December 13, 2013 12:45 PM writes...

I've never done astronomy (although I think it's cool), but I did have a fun telescope-related research experience. As an undergrad summer researcher, I built an automated system for collecting UV-visible spectra of the sky for trace gas detection. My system had a Newtonian telescope, an equatorial mount with two stepper motors, a separately-sourced stepper control board that I put in a Hammond box and that took RS232 commands, an adaptor my prof made for the exit to attach to a fiber optic line, which went to a USB-spectrometer cooled in a freezer, and a labview program to tie it all together. My program would automatically move the telescope to different directions and inclinations, determine light intensity for optimal integration time, collect averaged spectra and save to the hard drive, move to the next inclination and repeat, etc.

My only real problem was that the motors that came with the mount had a really fine step, presumably for smooth tracking of the Earth's rotation. Also, in general you can only drive a stepper motor so fast before it freezes up. Thus a position change would take a minute or three, where I would've preferred for it to go more quickly.

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16. anon on December 13, 2013 2:49 PM writes...

If you have an iphone or ipad, I suggest you consider an app like Starmap 3D+ as a guide. I assume similar apps may be available for android.

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17. Fred the Fourth on December 14, 2013 12:35 AM writes...

Speaking as an amateur who started by making a 6" Newtonian reflector from scratch back in '70, let me recommend an essential but overlooked item: comfortable warm clothes. Even in summer, standing around on a mountaintop from 11 PM to 3 AM with a bunch of other fanatics, one will get chilled without proper attire. I.e. something you might wear while downhill skiing.
Trust me. It won't matter what optics and mechanicals you have, if you are too chilled to enjoy them.

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18. RTP lab rat on December 15, 2013 6:44 AM writes...

I've had several telescopes, with my current one being a Meade 8-inch reflector. I've had trouble finding a good spot to store a telescope (per wifey), which seems to go from being in the LR, to the bedroom (makes a great clothes rack), to out the door on CL.
Spending much time in the lab watching liquids stir, it struck me that the parabolic surface could form a mirror if the container bottom was reflective. Has anyone tried using a gel to make a primary mirror like that?

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19. Thomas on December 16, 2013 7:35 AM writes...

I'll second the BMS researcher's view. I started with binoculars, a 10x50 pair, and found it great, took only a night or two to get the hang of star hopping and I was finding plenty of stuff.

Lately I've been using a little Skywatcher Heritage 76 (Americans, see the similar Orion Funscope). Doesn't give the views of a bigger scope but it's nice to use and I can be out observing with it in no time. I had a 4 1/2 inch reflector on an equatorial mount, that gave good views but drove me up the creek trying to use it!

RTP lab rat, liquid mirror telescopes have been made, usually using mercury (the element not the planet). They're very cheap for a larger aperture, but of course they can only point straight up. Large solid mirrors are I believe also spin cast, but because of thermal contraction when they solidify that doesn't give the precise final shape so they still need a lot of polishing and figuring.

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20. Lurker #753 on December 16, 2013 3:20 PM writes...

At least some of the cheap refractors in department stores/camera shops have surprisingly good optics, but always seem to come attached to lift-with-a-finger tripods - ghastly, flimsy, non-resisting, unusable WTFs.

A good astronomy tripod should:
- weigh more than the scope
- be almost entirely metal
- lock into shape
- have lock/release mechanisms that cannot fall off. (Shiny chromy butterfly nuts are an automatic disqualification).

One suggestion not made so far (for first-timers) is heavy binoculars + adapter + photography tripod. Big FoV is good for learning your way around, and in a dark site (yes, I know), you can go surprisingly deep.

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21. Anonymous BMS Researcher on December 19, 2013 8:43 PM writes...

Here's a pretty good site:

http://www.budgetastronomer.ca/index.php?page=faq

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22. Anonymous BMS Researcher on December 19, 2013 10:53 PM writes...

Here's a fascinating article in which an experienced observer pushes the limits of what can be seen with binoculars:

http://www.denverastrosociety.org/dfiles/eastman_saturn.html

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