It All Starts With The Mount
At some time or another, most amateur astronomers acquire through some means or another a telescope that doesn't have a tripod. Or, in some cases, a telescope with an inadequate mount. In fact, in today's market these are lots of inexpensive refractor telescopes out there that might tempt you, and most actually have quite good objective lenses in them. But most come with pretty shaky mounts, which pretty much ruins the experience.If you've done much shopping for telescopes and accessories, you know by now that a decent telescope tripod costs a couple hundred dollars or more, and that's for a mount for a small (less than 8 inch) telescope. A good example is the Celestron CG-4 German Equatorial Mount and Tripod
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This is a full equatorial mount of good stability,
and for a reasonable price as good astronomical telescope mounts go, but not
likely the mount you get with an inexpensive telescope. And when I started into
astronomy some 60 years ago, the general advice was that one should get an
equatorial mount.But the secret I've learned, once I decided that I enjoy observing more than the occasional and tedious endeavor of Astro-Photography, was that a well built altazimuth mount is much easier to use, and less expensive. For example, check out the Celestron Heavy-Duty Altazimuth Tripod
,
a perfectly adequate and easy to use altazimuth
mount that can certainly well handle a 60mm refractor.And here's another secret -- you can make the inexpensive DIY altazimuth telescope tripod described on this page and have a super-solid mount for any small telescope. With a couple of different attachments, this homemade telescope mount can easily handle any of my refractor telescopes ranging from 50mm to 70mm, or my compact Meade ETX 90 Maksutov. The total cost was only about $50 just a few years ago. I get double duty with this design, and if I happen to lay hands on another small scope to play with, it'll be easy to add an attachment to carry that telescope as well.
The Basic Tripod
A 2" flange is mounted to a double-layer 3/4" plywood base to hold securely the tripod post.
Three 1" diameter lengths of copper pipe extend from the center pipe to the extremes of the triangular base. Copper was used because the ends could be flattened for easy fastening to the center pipe and base. These lengths of pipe help make the tripod more rigid, stopping those annoying vibrations when you're trying you use your telescope on a high resolution target like the moon, Mars, or those close double stars.
An even more solid mount could be made by welding pipe legs onto the center pipe, and letting them extend to the ground. This would eliminate the plywood base, but require access to a welder.
I choose the wood base design at the time I constructed it because I didn't have a welder in my tool arsenal, a common dilemma I suspect.
On top of the tripod pictured is mounted an altazimuth head designed to support a 2" refractor. It would easily support a 70mm refractor telescope, and likely ann 80mm refractor. It's super solid if used with my 90mm Maksutov telescope, with which I use a wedge that puts the Maksutov in an equatorial mode.
By going to 2 1/2" or 3" pipe instead of 2", it could be sized up to handle larger telescopes.
The Tripod Feet
I mounted three 3/4" flanges to the underside of the plywood base.
Then I simply screwed in three short (each the same length) nipples into the flanges, and capped them to prevent them from digging into the ground.
The result is a stand that is portable enough to be easily moved around the yard, yet very sturdy.
In addition, about the only tools I needed was a pipe wrench or large pliers, and a drill.
The Tripod's Refractor Head
It consists of a coupling that connects to the base, an extender to raise the head to better accomodate the length of refractor telescopes, and the turn-on-thread bearing sections.
The azimuth bearing is formed by a 90 degree street elbow screwed onto the tripod post.
The other end of the street elbow screws into a flange that is mounted to a wooden bracket that holds a telescope. This makes the elevation bearing.
To make the thread bearings work smoothly, I polished the threads with some valve grinding compound obtained at a local auto parts store. The valve grinding compound is a kind of gritty, greasy paste.
I put some of the compound on the azimuth threads, then screwed on the street elbow. I repeatedtly tightened the street elbow to hand tight and then backed it off. The grinding compound polished the threads of both the extender pipe and the street elbow. After a few minutes, I was able to turn the fitting a couple of turns further then when I started. Once you've gained a couple of additional turns, the threads are probably polished enough.
I then removed the street elbow and cleaned the extender and street elbow threads, applied a light coating of grease, and screwed the street elbow back on. It now turns smooth as butter.
I did the same to the elevation bearing formed by the horizontal section of the street elbow and the flange.
The Tripod Supporting Refractor
While not light as a feather, the unit is light enough that I can leave the tripod and telescope assembled together, and still carry it out to set up, or move around the yard.
That provides some pretty short setup time, and lets me squeeze in some fun observing even if I only have 45 minutes or so for the entire session. I leave an f/17 60mm refractor on it most of the time, ready to go at a moments notice. The nice thing about the 60mm refractor telescopes is that they are light, and temperature stabilize quickly.
The telescope is easily and smoothly moved to each target desired, and remains in place from the slight stiffness in the large bearings. Pointing adjustments on target are made with light taps to the telescope tube. Vibrations from the alignment tapping stop immediately due to the mass of the tripod.
Tripod With Resuscitated 60mm Monolux
As an example, here's the same altazimuth refractor tripod head with a resuscitated 60mm Monolux telescope in place. The Monolux is an old Japanese designed telescope with a classic air-spaced objective. With a bit of loving care and a replacement 1.25 inch focuser, this telescope still makes a fine performer, and is supported very well by the pipe-fitting tripod.
Below the telescope, you can see the eyepiece table that's been added to the tripod. It's simply a 1/4 inch thick piece of plywood with several 1 1/4 inch diameter holes drilled into it, and fastened to a wooden mounting ring that clamps to the tripod post.
Adding Setting Circles
One thing you might consider as a refinement to your pipe fitting telescope
tripod is to add setting circles, as shown above. While setting circles are
more commonly a thing found on equatorial mounts, you can definitely use
setting circles to find celestial objects with an altazimuth mount.
The setting circles in this case were created with a perl script. The perl
script can generate setting circles of any given diameter, and marks them with
1 degree, 5 degree, and 10 degree tick marks. The perl script creates a
pdf file ready for printout.
Circles PDF
I made my circles to be 6.5 inches in diameter. The printouts of the setting
circles were mounted on 1/4 inch thick tempered hardboard and coated with Mod
Podge to protect them. The elevation settings need only be a quadrant going
from 0 to 90 degrees. The quadrant can be cut from a full circle.
I cut the elevation quadrant and mounted it onto the bracket that holds my
telescope, as shown. To properly position the elevation pointer, I first
leveled the tripod using a level on the base. Then I set a level on the
telescope and rotated the elevation bearing until the telescope was pointing
level. Next, I mounted a pointer (a large nail) so that it pointed at the
quadrant zero reading while the telescope was pointing level.
I mounted the azimuth circle by mounting it onto a split ring cut from
plywood. The split ring was cut a tad too small to fit over the shaft of the
tripod, but with a cut through the ring (the split), it can be sprung open
enough to fit snuggly around the vertical shaft of the tripod. In this way, I
can turn the azimuth circle to proper position when aligning the telescope. I
added a pointer for reading angular position.
You can get your own Setting Circle PDF copy here. This will allow
you to download a pdf file with a circle about 7.5 inches in diameter. You
can use a copy machine to rescale the image to the diameter you wish.
I took a print out down to a copy store and enlarged it to an 11x17 inch paper,
which gave me a 10 inch diameter setting circle. I used this to make an
azimuth setting circle for my Planetary Dob.
How Do You Use Them?
An easy way to make use of your setting circles is by using a planetarium program on a laptop. Xephem, Stellarium, or Kstars on a laptop lets you see a star map of what you might want to look at. You click on an item, and the azimuth and elevation show up on the screen. For Kstars, a right click will do it, then select details from the pulldown, then position. For Stellarium and Xephem it's a left click.To make easy use of azimuth and elevation values:
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Generally, if you've leveled your tripod and zeroed your azimuth on
Polaris, an object will either show up in your telescope FOV with a low
power eyepiece, or be just outside of the FOV and easily found with a bit
of careful searching. I have a program in an HP128 calculator that holds a couple of star catalogs (the Messier and Caldwell lists). It does the same translations as the computer planetarium programs, and gives me more portability. Pointing by setting circle saves me loads of time, especially on the dimmer objects that don't show in my finder. |
Amazingly, a pipe fitting telescope tripod with setting circles and an old laptop can automate your telescope to be nearly as handy as a computerized telescope. Is that neat or what?
The Cassegrain Wedge
The wedge is a simple triangle of wood cut to tip the telescope's polar axis by my latitude angle. A bit more thought and I could have built an adjustable wedge.
To the bottom of the wedge is mounted another 2" flange. The flange screws to the telescope base, giving a solid yet portable mount for the Meade ETX 90.
The Tripod Supporting Cassegrain
As you can see, the extender section of pipe isn't needed for the Cassegrain telescope since it is so short, so the extender has been removed.
I've found this to be a very solid mount for the ETX, and it would likely support at least a 4 inch Cassegrain as well.
Again, by scaling up the size of the pipe, a larger telescope could be handled.
This is the mount that was used for the Meade ETX 90 when it was used to make the moon images and planet images shown on the Etx 90 Astro-Photos page.
Personal Notes
If this cheap tripod design gives you some slack, money-wise, you might want to take another look at some small Cassegrains, knowing that with simple tools and tens of dollars you can make a fine tripod.You could also take the risk on perhaps a 60mm to 70mm refractor. The 60mm makes a great first telescope, but often is shipped with a flimsy mount. This mount would cheaply transform an optically decent 60mm into a fine performer. I use it often with a 60mm f/16.7 refractor, a 60mm f/11.7 refractor, and a 70mm f/12.9 refractor.
In fact, with any of the refractor telescopes I use on the tripod, the combo makes the easiest to use system I have out of my half-dozen or so telescopes. Just point and look. No knobs to loosen and tighten, and "no" vibration. Also, the tripod is so steady that the refractors in all cases allow me to focus without causing any annoying vibration. None of my other telescopes are that rock solid.
With a resuscitated old 60mm Monolux, my pipe tripod, and my setting circles I have hundreds of targets within my reach then can be located quickly, and hundreds of dollars or more of savings in my pocket.
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