I like to blog about non-fiction books as I read them, as it helps me both synthesize and retain the info. Chapter 3 is a general overview on all the computerized scopes in Celestron’s arsenal, and I found myself liberally highlighting as I read it. Here are some highlights:

• P.57 — a great overview of the different processors in the mount, including some of what the processors in the mount do (drive the motors) and the hand control (determining the correct tracking rate)…I was initially confused about something in the manual, as it said the hand controller sends the update to the mount every thirty seconds. I wasn’t sure if this meant it sends a “movement” command every 30s (as that seemed too slow) or a rate adjustment every 30s (adjusting the existing tracking speed), and the author confirmed the latter. Now rereading it, it was already clear, I think I just confused myself;
• P. 69 — I was surprised to see that there are CPC mounts that are actually quite well-designed for accurate tracking and thus support astrophotography. Maybe something to aspire too, instead of going Equatorial some day;
• P.78 — Good overview of the various types of hand-controllers, …I think I have the NexStar+ serial (Celestron button + RJ45-like jacks). I updated when I first got it seven years ago, but nothing since. From the author’s website, I clicked over to the Celestron list of bug fixes and updates…the only bug fix that seems really significant to me are the GPS rollover ones this year (like a Y2K problem), but I should probably do those. Fingers crossed I don’t brick my mount (I’m always nervous updating firmware for anything!);

The volume of material in the chapter is huge, although more of a reference chapter when you need specific info about different scopes, in my view.

I mentioned previously that it helps me to blog about NF books as I read them — kind of like transcribing my notes into something more coherent that my brain can recognize. Chapter 2 on Astronomy Basics in the NexStar User’s Guide II is a similar outcome. Here are some thoughts:

• P.12 — Constellations…There are 88 constellations that divide the sky…I always assumed there were WAY more than that. I’m curious if each of them will fit in an EP at 50x magnification which is my smallest / lowest power option;
• P.13 — Meridian…I knew horizon and zenith of course; I had not heard the term “meridian” to indicate a line going from northern celestial pole to southern celestial pole through the zenith to divide items west and east;
• P.15 — Magnitude…I wasn’t aware that a 1 magnitude increase in power equaled a 2.5x increase in brightness…I guess I just assumed a flatter linear scale. My son’s 4″ has a magnitude limit of 12.5, while my 8″ has 14, an increase not of simply 1.5 but of closer to 1.25 x 2.5 = 3.125 i.e. I can see way fainter stars. However, I have never figured out what a reasonable limiting magnitude in my backyard is, or anywhere else. Now that I see that magnitudes of clusters or galaxies are total luminosity of the object, without adjustment for diffusion across the object, I can see why supposedly bright DSOs do not show up clearly in my EP;
• P.17 — Seeing conditions…I confess I have always been somewhat fuzzy on the meanings of seeing and transparency, etc., and lumped them all together. I like seeing the definitions clearly explained as seeing = distortion caused by the layers of air; transparency = particles in the air; and light pollution = man-made light that is directed upward;
• P.19 — Observation…everybody includes descriptions of “averted vision”, but rarely have I seen it explained so simply and easily i.e. that the central retina is good for straight-on but the off-centre parts are good for detecting fainter objects, so looking to the side of the target lets the off-centre “see” the fainter areas. Equally, I like the description of using higher-magnification for bright, compact objects (like planets, globular clusters) while lower is better for fainter, distributed objects (like nebulae, galaxies, and open clusters);
• P.21 — Observation log…I already designed my own sometime ago, and I also am hoping to create my own app version some day. In the example given, the only thing I see that I don’t have is limiting magnitude, degrees above horizon, field diameter for observing and the constellation, and I generally ignored the first and the last while I didn’t have the info for the second and third;
• P.23 — Astrophotography…I was hoping for a bit more on this, but honestly, it could be a whole book on its own, and the suggested materials were good enough starters (i.e. ebook on SkyAndTelescope.com);
• P26+ starts to talk about key elements of basic observing, and most of it is stuff I already knew:
  • Get a moon filter;
  • The only thing you can see for Mercury is phases;
  • Similarly for Venus, no real details can be seen;
  • Mars is mainly pink- to red-colored disk, with lighter-colored polar caps and various dark surface markings;
  • For Jupiter, 4″ scopes (like my son’s) can see banding, while larger scopes can see details in the bands (supposedly) and moon transits;
  • For Saturn, you can see shadows of the rings on the surface as well as five of Saturn’s moons;
  • Uranus will be a fairly bright disc, blue in color;
  • Neptune can be distinguished from surrounding stars;
  • Pluto is only seeable in 6″ scopes and above, and then only as a pinpoint dot;
  • DSOs i.e. anything outside of our solar system are often very faint fuzzies;
  • Open clusters are stars that were born together and moving apart (didn’t know that);
  • Globular clusters are balls of stars held tightly together by their mutal gravity (didn’t know that either) and look good under higher power;
  • Nebulae are clouds of gas and dust, but bright nebulae have stars in them (reflecting nearby light or emitting their own) while dark nebulae block background stars;
  • Planetary nebulae are similar to planets in size and appearance, and are the remains of old stars, and higher power in higher scopes can show colour;
  • Galaxies are the bane of my astronomy experience as everything is always just a big or small faint fuzzy, mainly as I never get to a truly dark site…spirals (arms around central bulge), elliptical, dwarf/irregular … hard to tell what I’m seeing;

Once you get into the equipment, my knowledge drops off past the names. Sure, I can calculate that my 8″ scope has 4x the light-gathering power as my son’s 4″ version. And I get that longer focal length are good for moon, planets and similar DSO while shorter/faster focal lengths are good for open clusters and large nebulae. 

But what I was excited by was the explanation of exit pupils. Basically you divide the aperture by the magnification, sure, all the explanations say that, right? So, since my scope is an 8″, and an f/10, it ends up that exit pupils are exactly the EP size divided by the f/10 so a 41mm EP gives me a 4.1mm exit pupil. But what does that mean?

So the light coming from your scope is focused to a certain size image, i.e. it’s exit pupil. If my exit pupil is larger than the telescope’s, it’s all good. If the telescope’s size is larger than mine, I’m going to have to move my eye around inside of the EP to see the whole image. The explanation in the book isn’t any more awesome than previous ones, but the formula was better presented with examples, and it got me pushing harder to figure how it works for ME!

Well, it is like looking at a larger image through a small circle like a magnifying glass (without the magnification factor). If the hole I’m looking through (i.e. MY exit pupil), is bigger than the image (i.e. the telescope’s exit pupil), then I can see the whole image at once. If the hole I’m looking through is smaller than the image, I’ll have to move the circle around to see the image in sections.

And, it just so happens, I was testing my EPs about six weeks ago and figured out that in the 42mm BIG eyepiece that I was using, I was having to move my eye around a bit. In other words, that EP produced about a 4.2mm exit pupil, and my exit pupil was probably about 4.1 or 4.0 at that point. As the book points out (p. 41), “As we age, the muscles in our irises stiffen, and it is common for older observers to have a maximum dilation of about 5mm”. I would say without full dark dilation, I’m about 4mm-ish. But here’s the part that has ALWAYS confused me…I assumed that if my exit pupil was bigger, that was bad. Nope, it’s the opposite. As long as my exit pupil is 4mm, I can see EVERYTHING that is smaller than 4mm. So on my f/10 scope, everything below 40mm is going to work just fine for me. Above 40mm will still work, I just won’t be able to see the whole image at once. My son’s f/13 at 40mm will produce about a 3mm image, so everything will easily work for him or me. Finally, I get it!

Similarly, pages 43-48 run through all the different types of scopes in basic terms, and discusses some pros and cons:

• Refractors – Classic design, long tube with lens at front and EP at back — objective lens up to 6″ at the front collects light and focuses it at the back, and good for moon and planets, crisp and clear;
• Newtonian Reflectors – Two mirrors, with parabolic at back reflecting to small mirror at the front side — almost all large amateur scopes are Newts, with great bang for the buck yet open tube design;
• Schmidt-Cassegrain Catadioptric – like my 8SE, most compact for any aperture, uses front corrector plate at the front bouncing light off mirror at the back to mirror at the front that focuses on EP at the back again, and allows for closed tube, but can have excessive image shift when focusing;
• Maksutov-Cassegrain Catadiaoptric – like my son’s 4SE, MCTs have a curved corrector plate, and is great for contrast on moon and planets, but smaller FoV overall for large nebulae objects;

The chapter also covers the basics for different types of mounts such as alt-az, modified alt-az Dobsonian for Newtonian reflectors, and German Equatorial Mounts (GEM). 

And finally, I like the ending about eye-pieces:

• Eye-relief (the distance your eye can be from the EP and still see the whole image);
• Apparent Field of View; and,
• Using Barlows to step down from say 20mm with decent eye-relief to 10mm with decent eye-relief, rather than switching to 10mm plossl that frequently doesn’t have good eye-relief.

I am surprised in some ways for the chapter. Lots of stuff that I already knew in general terms, but I like the way it was explained and/or reading it for the seventh time in this format suddenly “clicked”. I finally get some of it. And it helped me make my decision on getting my son his 4SE, which is a Maksutov design.

I feel like I’m ready to learn the next part.

I have a Celestron NexStar 8SE telescope, and I have had some, umm, challenges dealing with alignment issues (Solving alignment problems with the Celestron NexStar 8SE). When I started surfing the ‘net to find some solutions, it didn’t take long to find out about Michael Swanson, the resident online expert for all things NexStar. He wrote the previous guide, he has an active website, he participates in online discussion forums. He’s everywhere you need him to be, except maybe in your own backyard when you’re viewing.

I finally caved and said, “Yes! I need that book!”. And then found out the new edition was about to come out. So I waited a bit, pre-ordered it, waited a bit more, finally got it, and immediately put it on my TBR pile and didn’t do anything with it. Sigh. I have about eight other astronomy books I want to devour cover to cover too, but this one is more practical. One of the few things that works for me with NF books when I’m dragging my feet to read them is blogging as I go, so I am going to try that here. I did it with Jeffrey Kottler’s “Change” – Chapter 1 and the 13 chapters that followed it before doing my final book review ( Change: What Really Leads to Lasting Personal Transformation by Jeffrey A. Kottler (BR00118)). Since this is the year where I want to test everything astronomical, and work out my mental bugs, I thought maybe I would heed the classic advice of RTFM, or in this case, read the f***ing after-market user’s guide wouldn’t be a bad starting point. I’m not going to summarize the chapters, mostly I’m just going to highlight what I learned from each one that I didn’t already know or that I felt was well done.

Chapter 01, the Introduction, runs a short 9 pages. Here are some highlights:

Page 2: Under a section called “Are GoTo Scopes Appropriate for Beginners“, Swanson goes to the heart of the frequent debate. Lots of astronomy types prefer reflectors over refractors, Dobs over Maks, blah blah blah. And are quite adamant that their preference is the one true view. One area where you frequently run into this is the question of GoTo scopes, where many sniff that it is a terrible way to learn astronomy, that you don’t learn anything just doing point and go. Except you do, as Swanson points out. You learn the night sky, and where things are, you just don’t learn to do the initial (often very frustrating) act of star hopping. Even the Royal Astronomical Society of Canada, of which I am an active member, embeds this in their observing certificates — if you are using a GoTo scope, you’re not eligible for the certificates or pins. Since YOU didn’t find the objects, YOU don’t get recognition for the observing. Although, you might be able to fake your way in through at least sketching the objects (the rules aren’t clear on that point), but I digress.

I love the paragraph in the book however, I guess because it EXACTLY summarizes my own view — “Granted, some will not follow through in acquiring even this computer-assisted knowledge [of the sky and sky hopping], but would they have taken the much steeper path by learning to star hop?”. For myself, the clear answer was no, I wouldn’t have. I have a GoTo scope precisely because it cut the opening learning curve so I could be observing quickly and maintain my interest. If I was star hopping from A to B to C, and “trying” to see if I could find D, I would have been REALLY frustrated. I didn’t know what to expect, and some of the objects are so faint and fuzzy, I wouldn’t have known if I was successful or not. And probably would have just thought I was stupid. I needed to prevent the frustration from killing my interest before I even got into it. Of course, my subsequent alignment problems didn’t help with that, but I digress again!

Page 4: The main chunk of the chapter is the history of NexStar scopes, and it was interesting to read. I also liked the summary of common characteristics of GoTo scopes — motor drives on both axes, encoders to keep track of the location of each axis (oh, so THAT’S what encoders do!), handheld computers or connections to other devices with a database of objects, and controls (hand or on the devices) to tell the scope where to move to and how to stay tracking the object.

Page 7: I hadn’t realized the StarSense AutoAlign accessory came about in 2013 nor did I view it as being something for all of the computerized mounts. I really only thought of it for my own, not as a “whole line” accessory, although of course it would be. I am interested in trying the Star Sense sometime to see how big a difference it makes on my scope. If I understand it correctly, it basically adds a “seeing eye dog” to the scope so that rather than me pointing it at a star as part of the alignment process, it itself figures out which stars it can “see” with the camera, and does up to ten stars to get a much more accurate alignment. Sounds awesome, but I am reluctant to pay the $500 price tag if it is only marginally better than what I do on my own, but since alignment is a huge pain in the patootie for me, I definitely want to try it and compare. Of course, though, it adds weight to the scope, a not-insignificant concern on a fork arm.

For me, it was an auspicious beginning chapter. I like his style and voice, I’m learning stuff even in the short intro chapter, and gives me hope I won’t bog down in the middle of a dry discussion of something like exit pupils (one of my nits to pick with the annual RASC Observer’s Guide).

Onward!