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Friday, April 5, 2013

Praise For The Venerable 60mm Refractor

At left you see an image of one of my favorite telescopes, my 60x1000mm Carton refractor. Yes, that is a homemade pipe fitting mount you see holding the telescope.  Click on the link to see how to make your own.

What brings me to this post is the experience I had most recently with this particular telescope. An experience that reminded my of why I enjoy it so much.

Not long ago I acquired a NexStar 5SE from an online acquaintance, and have been furiously learning how to use it, and comparing it to some of my other telescopes. There'll be more on that effort in another post.

But one consequence of comparing telescopes is that you find yourself very busy in the mechanics of observing, like locating the same object in each instrument, adjusting magnification in each to be comparable, and straining to see tiny details or the dimmest stars in the compared views.  But what you don't tend to get out of that experience is the simple enjoyment of viewing each target in a relaxed setting.

So recently, instead of another evening of tests, I wanted to just go out and enjoy an evening under the stars. Enjoyment for me means using a telescope that is easy to set up. It also means using a telescope that is easy to operate. And, finally, using one that lets me effortlessly find targets, so I spend the evening observing, not searching, or struggling with the apparatus.

For me, that usually means grabbing one of my two 60mm refractors. I have a 700mm focal length resuscitated Monolux, and a slapped together from available parts 1000mm focal length Carton. That is, the objective lens is made by Carton. See for yourself the simple construction of the Carton Refractor Telescope.

In case you feel at this moment that there is madness in thinking one can enjoy star gazing with a mere 60mm telescope, I challenge you to read on.

A Wonderful Madness

Take the other night as a case in point.  In only an hour and a half or so of observing with my 60x1000mm Carton, I observed Jupiter and a host of Messier objects, plus a couple of nice double stars. The Messier I observed were open clusters M46, M48, M35, M36, M37, and M38.

I also observed the M3 globular cluster, the M42 Orion nebula, and galaxies M81 and M82. I could just get both of the galaxies in my field of view when using a 25mm focal length Plossl eyepiece. I also took a peek at M45, the Pleiades. With the 1000mm focal length, the Carton telescope didn't quite span the extent of the beautiful Pleiades, but the 700mm focal length Monolux can, and delivers a fantastic view of the sparkling stars of the Pleiades.

Now that's not a bad evening, especially considering that a great deal of that time was spent in watching Jupiter and 3 of its moons. Ganymede and Io were approach Jupiter from one side, while Europa was approaching from the other. I hadn't checked my almanac that evening, so I wasn't sure from which side of approach the moons would cross in front of the planet, and from which side the moons would disappear behind the planet.

So I spent considerable time watching what turned out to be Io and Europa inching closer and closer to the planet. I knew that if I waited long enough, one or the other would pass in front of the planet (the other passing behind), making a shadow that I thought I'd be able to see with my 60mm.

I have seen Io's shadow with a 60mm before, so I was pretty confident in my instrument. But, as it happened, the shadow was going to become visible too late, and I'd already promised my spouse I'd come in and watch a mystery movie.


So how did the Messier look through my modest 60mm?

All of the open clusters, the Pleiades, and the Orion nebula were very enjoyable views. M3 was clearly visible as a dense, small cloud. The M81 and M82 galaxies were the toughest targets for the 60mm. They were easy to see, but appeared as ghostly objects. Still, I could tell that one was a fat elliptical object, and the other a very thin (edge on) elliptical object.

Pipe Mount Setting Circles

How do I find the star targets?

As the above image illustrates, I've added setting circles to my simple pipe-fitting mount. With the setting circles, all I need now is my cell phone, and I can find any Messier, Caldwell, or Herschel 400 object that is within grasp of my telescope.

How, by calling for help?

No, by using the Star Pointer web site, which presents a utility that if allowed to use your Latitude and Longitude location, call tell you in real time where to point your Altazimuth or Equatorially mounted telescope. It presents pointing coordinates for either coordinate system, and updates the coordinates every 30 seconds. Telescope with setting circles, cell phone, and a warm coat -- that's all I need.

Some Good Reasons To Use A 60MM

Here's a list of my reasons that I think justify use of such a modest instrument. The list is predicated on two things: that the telescope is of good quality, and that it is solidly mounted. Does that mean you need a $600 telescope and a $300 mount?

Nah!!

You can use a vintage 60mm from the past, typically available on Ebay for maybe $150, or at a garage sale for considerably less. Tune it up a bit, and you'll find that those old 60mm telescopes were no kids' toys.

And you can make a Pipe Fitting Mount as I did for only tens of dollars. And that pipe mount will be the most solid tripod you'll likely ever experience. Mine is made with 2 inch diameter pipe with polished and lubricated threads on the turning axes. You can find instructions on the link.

With that size pipe, a telescope balanced in its cradle lets me just point the telescope and look. I don't need set screws or slow motion controls. A light tap on the telescope will move it a few arc-seconds to adjust the target position, and the vibrations damp out immediately. I can focus without causing any vibrations -- the only telescope I have, commercial or otherwise, that's rock solid enough to let me focus without inducing vibrations.

I use a "push to" method for locating objects. I have an old HP 48 calculator programmed with the necessary math and 3 star catalogs so that I can simply select an object from one of the catalogs, and the calculator displays the azimuth and elevation for that target. If you aren't interested in programming a calculator in a similar manner, you could alternatively use a laptop and something like Xephem to give the same data. You could probably even find a smartphone or tablet app that will give you azimuth and elevation information for astronomical targets.

Since the pipe mount has setting circles on it, I just move the telescope to the selected coordinates, and if I've done a decent alignment of the telescope, the object will be somewhere in the field of view.

What does the alignment procedure consist of? Even that is simple. I level the base, which has two of the three feet made from threaded bolts, making leveling easy. Then I point the telescope to Polaris and turn the azimuth wheel to read zero -- done!

As to the calculator, I look up the current Sidereal time for my location before I go out (I use the Xephem Planetarium Program for that, but you can just look it up with the Sidereal Time Calculator). I enter that Sidereal time into my calculator, and it's set for the evening. It has it's own internal clock, so it can propagate Sidereal time during my observing session. And, as pointed out earlier, if you're not the computer nerd I am, just use your laptop and a planetarium program.

Once I've obtained a target's azimuth and elevation data, I just move the telescope to the indicated angles. With the heavy-duty pipe tripod, there's no need for clamps or slow motion controls -- it couldn't be easier.

Oh, and did I mention that a 60mm refractor can be producing great images within only a few minutes after setup? No need for an hour or two cool down. By the time I level my tripod and align on Polaris, I'm ready to start observing.

One more advantage of the 60mm size telescopes -- portability. The telescope and tripod, even my pipe mounting one, can be left assembled and moved around without any disassembling. Mine sits ready for action in my shop. Of course, I keep the telescope tube ends covered when it's not in use.

So there you have it, the 60mm is:
1) Quick to set up.
2) Reaches thermal stability quickly.
3) Alignment is easy.
4) Push to makes finding objects quick (or star hop if you prefer).
5) Rock steady views with a very simple mount.

But Can You See Anything?

You can see a great deal. Nearly all of the Messier (some say all) can be seen with a 60mm, if you have a reasonably dark viewing site. Granted, the galaxies are dim, but most are visible. And the star clusters are great.  There are many double stars that 60mm refractors can do wonders with. And cloud bands on Jupiter, Saturn's rings, the phases of Venus, and even some details on Mars can be seen.

Jupiter through 60mm
On a clear evening, Jupiter, for example, can reveal some tantalizing details. The image at left, was taken through my 60mm Carton using a Celestron NexImage webcam.  Actually, you can often see more detail than is captured in this image, though in a 60mm the colors don't show up as in this image.

Do you notice anything unusual about this photograph? The SEB (South Equatorial Belt) is missing! This photo was taken in 2010, when the mysterious SEB did it's occasional disappearing act. It's back now (2013,) so don't despair. But just note that the disappearance and reappearance of the enigmatic SEB was quite visible through a 60mm telescope.

Plato through 60mm 
And the moon!  Eat your heart out. The image at left was taken of the Plato region (one of my favorites), using my Celestron NexImage webcam and my 60mm Carton refractor.  The individual mountain peaks Piton and Pico are easily visible, as well as is the Alpine Valley.

Imagine trolling over the moon at such detail. You can, with just a decent 60mm refractor on a solid telescope mount.


Tycho through 60mm
The moon through a 60mm shows a wealth of detail. And each time you go out to look, the sun is illuminating the moon at a different angle, leading to different details.

This image of Tycho, also taken with the NexImage and my 60mm Carton refractor, shows one face of Tycho. At this sun angle, the internal structure of Tycho is revealed, showing a large and small mountain peak at the crater's center. Not bad detail for a 60mm. But during a full moon, the fantastic ray system of Tycho dominates instead of the intricate details shown here.

Additional photos taken through my 60mm Carton can be found at my 60mm Astrophotos webpage.

So don't let anyone tell you that your 60mm telescope, if you have one, is useless. That's true only if the telescope sits in a closet all the time. Get it onto a good mount, obtain a few decent eyepieces, and go for it. While I don't use a 60mm all the time, as I have some larger telescopes, it's certainly the quickest scope to set up that I have, and additionally the easiest to use.