So I’ve been thinking again. No, no need to duck and cover this time.  This hasn’t anything to do with dangerous things.

There’s times when I’m actually rather bored lately.  I’d love to do something like going shooting in the desert, but then ammo costs $$$.  And by $$$ I mean LOTS of $$$.  For example, 20 rounds of AK-47 ammo costs $7.00 and can be used up in seconds.  When I can find bulk packs of .22 ammo, they’re about $15 – $20 for 500 rounds.  That will last an afternoon or two depending on what you’re doing.  But it’s still a bit expensive.  My K-31 costs about $1.00 per round to shoot and the Mosins are either $10 for 20 rounds of good surplus ammo (that won’t nearly weld the bolt shut) or $25.00 for 20 rounds of new production ammo.  I love shooting, but it’s not something I can do anytime I want to.

And then there’s the fact that you can’t really go anywhere to shoot after dark that’s not an indoor range that costs $15 – $20 for range time.  This time of year it’s dark by the time I manage to get out of work.  So what to do aside from wander around the strip or surf the Internet?  Not much on a budget.

So I got to thinking about just what I could do and something came into my head from somewhere in the darkness.  It would require a decent initial investment, but after that would only require gas and limited cleaning supplies on occasion.

If you’ve guessed that I’m thinking about a telescope, you’re correct

Follow my line of thinking here.  For a telescope to work best, it needs a dark sky.  While Vegas is a pretty bright place, it doesn’t take much driving to get somewhere pretty dark.  A few times a year it would be possible to go somewhere like the Black Rock Desert.  I’ve been to the Black Rock Desert once about three years ago and there’s something I’ll never forget about that trip.  I simply couldn’t believe the amount of stars!  It wasn’t just the Milky Way either.  There were so many stars that even without the moon, I had no trouble seeing.  It was as if the moon was up and fairly bright   That experience has stayed with me since then and comes back frequently when I look up at the night sky.

Aside from the dark skies in Nevada, there’s something else this place has to offer astronomers – clear, dry air.  OK, so dust might get in the way when the wind blows and that will shake the scope a bit, but it’s not windy often enough to matter in this case.  In any case, there are very few times when the humidity goes above 20% which helps quite a bit.  All things considered, I’m probably in one of the best possible locations for astronomy in North America

The trouble is that if I’m going to buy a telescope I’m not going to want a toy and that brings us to a few decisions which will greatly affect the means of use and capabilities of the scope.  There’s trade offs everywhere in this field (as in many others) from what I’ve learned in my research.  There’s quite a bit you have to take into account before you can make a reasonable, informed decision on what to buy.

There’s three main types of telescopes – reflectors, refractors, and catadioptrics.  And then there’s the types of mounts – dobsonian, altazimuth, and equatorial.  Finally, there’s the question of aperture – how big the diameter of the optical tube is and in this case bigger is definitely better.

From Telescopes.com:

Refractors have their strong points – great colors, little distortion, and a higher percentage of transmitted light are all reasons to get a refractor.  The big downside of refractors is the cost for a given aperture.  Another downside of refractors is that unless you spend some really big bucks, you’re going to have a bit of chromatic aberration (false color) around light sources.

Reflectors have a big advantage in the area of price per a given aperture because they only have one optical surface that has to be precisely curved – the primary mirror.  They produce great images, but they do produce a diffraction pattern like a star around point light sources due to the “spider” or support legs which support the secondary mirror at the top of the tube.  The other downsides of reflectors are “coma” which causes distortion around the edges of the image, size, and weight.  Still, these are the biggest bang for the buck in telescopes.

Catadioptrics are a bit of a combination of the reflectors and refractors.  Catadioptrics are reflectors, but they also use lenses.  They’re great scopes that don’t suffer from diffraction as they use a lens at the top to hold the secondary mirror so they don’t need a spider.  They’re also rather short as they fold the light path to make it longer.  The biggest problem with catadioptrics is again price for a given aperture.  They also have a lower light transmission percentage than either refractors or reflectors and they also have a problem with viewing objects nearly directly overhead due to the location of the eye piece.

After making the decision about the type of scope, I have to figure out what type of mount I want.  The mount is another big money decision.

Altazimuth mounts work in altitude and azimuth planes – think vertical and horizontal.  Dobsonian mounts and fork mounts are types of altazimuth mounts.  Fork mounts are just like a bicycle fork for the front wheel.  Dobsonian mounts are kind of like a fork mount, but are larger, wider, and generally lower to the ground.  One smaller type of dobsonian mount uses a single arm to hold the scope tube.  These mounts, especially the dobsonian mounts (which are usually made out of wood or particle board) are usually relatively inexpensive.

Equatorial mounts are aligned with the polar axis of the earth and allow the scope to follow the apparent motion of stars and other objects through the night sky caused by the earth’s rotation.  Equatorial mounts are more expensive due to the gearing required to make them work, but they are more convenient for observers and pretty much required for astrophotography.

One other thing I have to take into account is the focal length of the scope.  Longer scopes are dimmer for a given aperture, but shorter ones can cause distortion.  Along with these concerns, focal length is an essential part of calculating magnification.  Eyepieces are interchangeable and are how you change magnification.  Magnification is calculated by dividing the focal length of the scope by the focal length of the eye piece.  A 1500mm focal length scope with a 10mm eyepiece would yield 150x magnification while a 1000mm focal length scope paired with a 10mm eyepiece would be 100x magnification.

Finally there’s the question of aperture.  How much is enough?  The problem is that when all other things are equal, the bigger the aperture, the bigger the price, but the more capable the scope.  As you go to higher magnification power, objects get dimmer and if you go too high will distort if you don’t have a big enough mirror or lens.  To get a usable image, you have to go bigger on the lens or mirror if you want to go to high enough powers to actually see galaxies and clusters as more than smudges.

So here’s the deal.  I’m strongly leaning towards a reflector telescope due to the bang for the buck.  If I go with a dobsonian mount, I’ll be able to see more, but I’ll have to manually point the scope with a handle and track anything I see by hand.  If I go with an equatorial mount, I’ll be able to track objects easier, possibly add a motor drive in the future for automated tracking, and would have the capability to do some interesting photography.  I’m leaning toward a dobsonian mount for my first scope.  I want to see as much as possible – the clearest views of Saturn, Jupiter, and galaxies.

But just how much is enough?  A small 3″ scope can go for as little as $50, but is pretty limited as to what can be seen.  The biggest consumer scopes can be 14″ in diameter or more, but will cost as much as you can spend – $2,000 and up.

The scopes I’m trying to decide on fit right about into the middle of this range.  The question is whether to go with a bigger aperture on a dobsonian mount or a slightly smaller aperture on an equatorial mount.

Here’s a few of the examples of what I’m looking at:

So those are some of the scopes I’m looking at.  Click on the pictures for the manufacturer’s website for each scope.

The big problem I’m facing is capability vs. cost.  I can fit even the biggest of these scopes in my car, so that’s not an issue and I can also get to a dark sky site in a relatively short time with little capital expenditure which means that the “big guns” in this group would actually work for me where they might not work for someone else.

Remember when I said I didn’t want a toy?  What I mean by that is that I really want to be able to see some good detail.  I want to see the small things on the moon, really good ring detail on Saturn, and cloud bands on Jupiter.  I’d like to see polar ice on Mars.  I don’t want to see a fuzzy haze when I look at a distant galaxy or star cluster – I want to see a recognizable galaxy or star cluster.

So what can you expect to see with a given telescope size?  According to astronomics.com, it goes like this:

PERFORMANCE – WHAT CAN YOU EXPECT TO SEE IN A TELESCOPE?

TYPE OF SCOPE	WITHIN THE SOLAR SYSTEM	STARS	DEEP SKY OBJECTS
60mm to 70mm refractor, at powers of 25x to 125x (solar system objects generally need 60x and up)	sunspots (with an appropriate solar filter); the phases of Venus; lunar craters as small as four or five miles in diameter; several cloud belts on Jupiter, plus the four Galilean moons; the rings of Saturn (and occasionally Cassini’s division, with good seeing); Uranus and Neptune visible as small greenish points	double stars separated by as little as 2 arc seconds in good seeing; faint stars down to magnitude 11.5	the larger globular star clusters, some of the brighter nebulas, virtually all of the Messier objects from a dark sky site (although with relatively little detail visible in many of them)
80mm to 90mm refractor, or 4″ to 4.5″ reflector, or 3.5″ to 5″ catadioptric, at 16x to 250x	structure in sunspots (with an appropriate solar filter); the phases of Mercury; lunar rilles and craters less than three miles across; Martian polar caps and major dark surface features during oppositions; several additional cloud belts on Jupiter, with some detail in the belts, plus the shadows of Jupiter’s moons on the planet during transits; Cassini’s division in Saturn’s rings on a regular basis, plus four or five of its moons; Uranus and Neptune visible as very small discs	double stars separated by 1.5 arc seconds or less in good seeing; faint stars to better than magnitude 12	dozens of globular clusters, emission nebulas, planetary nebulas, and galaxies; all of the Messier objects and many of the brighter NGC objects from a dark sky site (with some internal detail visible in many nebulas, although most galaxies will remain relatively featureless hazy patches)
4″ to 5″ refractor, or 6″ reflector, at 30x to 300x	domes, rilles, and other lunar features less than two miles across; many more dark surface features on Mars, often during less-than-favorable oppositions; festoons, streamers, and much more detail in Jupiter’s cloud belts with good seeing; subtle cloud belts on Saturn’s disk; many faint comets and brighter asteroids	double stars separated by about 1 arc second in good seeing; faint stars down to magnitude 13 or better	hundreds of star clusters, nebulas, and galaxies (with hints of spiral structure visible in some galaxies); many, many NGC and IC objects from a dark sky site (considerable detail in nebulas and clusters)
6″ to 7″ refractor, or 8″ reflector, or 7″ to 9.25″ catadioptric, at 50x to 400x	lunar features under one mile across; large clouds and dust storms on Mars; as many as six or seven of Saturn’s moons; Jupiter’s four Galilean moons start to show as tiny (albeit featureless) discs at high powers; many dimmer asteroids become visible as faint star-like points; seeing conditions start to limit how much solar system detail you can see on an average night	double stars separated by less than 1 arc second in good seeing; faint stars down to magnitude 14	some globular clusters resolved almost to the core, much internal detail in nebulas and some visible structure in many galaxies from a dark sky site
10″ or larger reflector or catadioptric, at powers of 60x to 500x	during infrequent excellent seeing conditions, lunar features to much less than one mile across; small clouds and significant surface detail on Mars, with moons Deimos and Phobos a rare possibility; a wealth of detail in Jupiter’s clouds and belts; Enke’s division in Saturn’s rings often visible; Neptune’s moon Triton visible; Pluto visible as faint star-like point; the amount of solar system detail visible will usually be limited by the seeing conditions with large scopes like these, making them less than ideal for regular solar system observing, despite their high resolving power	double stars separated by as little as 0.5 arc seconds in excellent seeing conditions; faint stars down to magnitude 14.5 and below	thousands of globular clusters, nebulas, and galaxies – virtually all NGC and IC catalog objects – with many showing details invisible in smaller telescopes; faint color visible in some of the brighter nebulas from a dark sky site; it is in viewing these faint objects at low to medium powers that large scopes such as these excel

There’s a few other things I know I’ll be buying in the future like optical filters and different power eye pieces, but they all work with the scope and mount as the heart of the system.

To tell the truth, I’m leaning towards the $330 8″ (203mm) dobsonian, the $280 6″ (150mm) dobsonian, or the $300 5″ (130mm) equatorial with the 6″ and 8″ dobsonians gaining favor every day.  Reviews for many different scopes can be found at scopereviews.com with specific reviews on the 10″, 8″, 6″, and 4.5″ dobsonians all getting good marks.

Remember that part about aperture being one of the most important aspects of a telescope?  I made up a little table that might help some people understand this a bit better.  It shows the area (in mm²) of a given diameter disk (or mirror) and a comparison of the amount of light gathered by each.  I’ve added in two of the world’s biggest and most famous telescopes as a fun comparison to the consumer scopes.

Gran Telescopio Canarias – Largest in the world
409″ = 10400mm diameter = 84905600 area
10400mm = 1872576% as much light as 76mm
10400mm = 1335308% as much light as 90mm
10400mm = 832256% as much light as 114mm
10400mm = 640000% as much light as 130mm
10400mm = 480711% as much light as 150mm
10400mm = 262466% as much light as 203mm
10400mm = 167648% as much light as 254mm
10400mm = 85342% as much light as 356mm
10400mm = 10478% as much light as 1016mm
10400mm = 419% as much light as 5080mm

Mt. Palomar Observatory
200″ = 5080mm diameter = 20258024 area
5080mm = 446786% as much light as 76mm
5080mm = 318597% as much light as 90mm
5080mm = 198571% as much light as 114mm
5080mm = 152700% as much light as 130mm
5080mm = 114695% as much light as 150mm
5080mm = 62623% as much light as 203mm
5080mm = 40000% as much light as 254mm
5080mm = 20362% as much light as 356mm
5080mm = 2500% as much light as 1016mm

40″ = 1016mm diameter = 810320.96 area
1016mm = 17871% as much light as 76mm
1016mm = 12743% as much light as 90mm
1016mm = 7942% as much light as 114mm
1016mm = 6108% as much light as 130mm
1016mm = 4587% as much light as 150mm
1016mm = 2504% as much light as 203mm
1016mm = 1600% as much light as 254mm
1016mm = 814% as much light as 356mm

14″ = 356mm diameter = 99487.76 area
356mm = 2194% as much light as 76mm
356mm = 1564% as much light as 90mm
356mm = 975% as much light as 114mm
356mm = 749% as much light as 130mm
356mm = 563% as much light as 150mm
356mm = 307% as much light as 203mm
356mm = 196% as much light as 254mm

10″ = 254mm diameter = 50645.06 area
254mm = 1116% as much light as 76mm
254mm = 796% as much light as 90mm
254mm = 540% as much light as 114mm
254mm = 415% as much light as 130mm
254mm = 312% as much light as 150mm
254mm = 170% as much light as 203mm

7.99″ = 203mm diameter = 32349.065 area
203mm = 713% as much light as 76mm
203mm = 508% as much light as 90mm
203mm = 317% as much light as 114mm
203mm = 244% as much light as 130mm
203mm = 183% as much light as 150mm

5.90″ = 150mm diameter = 17662.5 area
150mm = 389% as much light as 76mm
150mm = 277% as much light as 90mm
150mm = 173% as much light as 114mm
150mm = 133% as much light as 130mm

5.11″ = 130mm diameter = 13266.5 area
130mm = 292% as much light as 76mm
130mm = 208% as much light as 90mm
130mm = 130% as much light as 114mm

4.48″ = 114mm diameter = 10201.86 area
114mm = 225% as much light as 76mm
114mm = 160% as much light as 90mm

3.54″ = 90mm diameter = 6358.5 area
90mm = 140% as much light as 76mm

2.99″ = 76mm diameter = 4534.16 area

Most of my readers know me well enough to know that I’d love to have a 36″ monster telescope if I could   Sadly, I don’t have the $15,000 to buy it, a way to transport it, and it’s out of production.  While I know where to find a 25″ telescope, it’s still too big and most regrettably too expensive.  In a move that shocked Cindy and will likely shock others as well, I’ve decided that the best course of action is to go with a moderate telescope that’s still a beginner’s scope – something that won’t break the bank and is easy enough to transport, but will still allow me to see the good stuff

I don’t know when this will happen.  It could be in the next few months or six months from now, but I’m pretty sure that it will happen

Have fun and clear skies, everyone