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Stargazing July 13th ✦ 7pm-10pm
Stargazing July 13th ✦ 7pm-10pm
The Basics of Using a Telescope

The Basics of Using a Telescope

Getting started stargazing is easy, but there are some helpful hints to know in order to make using your telescope easier. The other pages of theUsing a Telescope section give specifics on polar alignment, balancing, and aligning a computerized telescope, as well as more advanced techniques such as collimating and cleaning optics. Below you will find some tips on doing the basics to get a telescope up and running.

Aligning a Finderscope

After putting your new telescope together, but before you can use it, you will need to align the finderscope with the main telescope. Once this is done, whatever you aim to with the finderscope will be visible in the main scope. There are two basics types of finderscopes: optical finders andreflex finders. An optical finder is just a small telescope with a set of crosshairs, like a riflescope. The main drawback to optical finders is that they normally present an image that is upside-down and backward. Reflex finders, like the popular Telrad, project a red dot or bulls-eye onto a small piece of glass. The result is that the dot or bulls-eye appears to be up on the sky. Reflex finders have no magnification and do not flip the image, so they tend to be much easier to use.

The easiest time to align a finderscope is during the day. Begin by pointing the telescope at a distinct target at least a few hundred yards away. Telephone poles, treetops, and mountain peaks are all good choices. Just make sure you know what object you are aimed at. Next, look through the finderscope and see where it is pointed. With an optical finder, there are normally three small screws that must be adjusted to align the finder. This can be a little tricky if everything is upside down, but a little trial and error will determine which way the screws need to be turned. With a reflex finder, things are usually easier since the image is correct. Depending on the type of finder there will usually be two screws for up and down, or three screws that move the target at angles.

Above: A prominent target centered in the eyepiece (left) and in the finderscope crosshairs (right)

Always be sure to check the view through the main telescope when finished with the finder to be sure the telescope did not get bumped during the alignment process.

Using a Finderscope

Once the finderscope is aligned, you can use it to find objects in the night sky. For some objects like the moon and planets, this is pretty easy. With an optical finder, it takes some time to get used to the inverted image, but pretty soon you should be able to quickly point to bright objects. Finding bright targets with a reflex finder is even easier. But the real trick is hunting down objects that are not visible in the finderscope. To do this, you must use a chart and a technique called starhopping. This is much easier to do with a reflex finder since it does not magnify the sky or change the view you have of the stars. (Trust us on this one, adding a reflex finder to your telescope is the best thing you can do to make your stargazing simpler!) But starhopping with an optical finderscope is not terribly hard with some practice.

Suppose you want to find the Whirlpool Galaxy, M51. This object is too faint to see through most finderscopes, and is invisible to the unaided eye. Consulting a basic star chart shows that M51 is located near the end of the handle of the Big Dipper. Imagine the angle and distance from the last star in the Dipper's handle to the galaxy. With a reflex finder, things are easy: just aim the red dot or bulls-eye to that area of the sky, and with a low-power eyepiece you should see the galaxy in the telescope. With an optical finder, it is harder to tell exactly where you are in the sky because you lose the reference stars you can see with the unaided eye. The trick now is to look for recognizable patterns in the finderscope that correspond to patterns seen on the star chart. Of course, you must remember the image through the finderscope is upside-down and reversed relative to the chart. (Have you ordered your reflex finder yet?) Once you identify some patterns in the area of M51, you can tell which way to move the telescope to aim to the right part of the sky.

Above: Finding a deep-sky object with a reflex finder

Above: Finding a deep-sky object by starhopping with an optical finder. In this case, you might begin by finding the relatively bright star below the last star in the handle of the Big Dipper. Then moving down and left would take you to a distinct pair of stars. A small move up and left will find the target.


New stargazers often underestimate the importance of focusing the telescope, especially when a group of people is viewing. Everyone's eyesight is different and each observer should focus the telescope for her own eye. Eyeglass wearers may be able to remove their glasses to view. Adjusting the focus of the telescope will compensate for nearsightedness or farsightedness. It will not, however, correct astigmatism, so observers with this eye aberration will have to keep their glasses on. Just a small difference in focus can make a big difference in image quality. Be sure to focus each time you look, and have your guest stargazers do the same. Many people are hesitant to touch someone else's telescope, so be sure everyone viewing knows it's okay to adjust the focus.

Moving a Telescope Around the Sky

Pointing a telescope where you want in the sky is not always straightforward. With an alt-azimuth mounted telescope, such as a Dobsonian, the movement is intuitive: up-down and left-right. But with an equatorial mount, getting the telescope aimed can be trickier. With a German equatorial mount, one axis (the polar axis) of the mount always points north. Imagine the sky divided into two halves on either side of this axis, east and west. Beginning with the telescope in its "home position" pointing north over the mount axis, you can simply move the front of the telescope to the half of the sky you want to see. This is tricky for objects in the south; it is easiest to stand to the north of the mount and look over it to see if the object is east or west of the polar axis. The other trick is getting from one half of the sky to the other. Always bring the telescope back through north to switch sides of the sky. This will keep the scope from flipping upside down.

Transporting a Telescope

A telescope contains delicate optics and transporting it should be done with care. While a protective carrying case is recommended, it is not always necessary. A scope can handle a little bouncing around as long as it is padded. Many people will simply wrap a telescope in a blanket and buckle it into the back seat to drive out to a star party. This works especially well with larger Schmidt-Cassegrain telescopes, which are the perfect size and shape to sit in a car seat. Hard cases offer the best protection and can carry accessories in addition to the telescope itself. For larger telescopes, cases often have wheels, making it easier to move things around. If you plan on taking your telescope overseas or somewhere requiring a flight, it is recommended that you ship the telescope to meet you rather than put it onto the airplane. This is because you can insure a telescope when shipping it, but not usually when you transport it on an airplane. Not to mention that, as rough as they are, shippers are still gentler than baggage handlers. If you have to transport by plane, use the telescope's original shipping container rather than a case, and sit on the side of the airplane opposite the cargo doors so you don't have to see what's happening to your telescope.

Storing a Telescope

Where and how you store a telescope is very important. We have had customers bring in telescopes that were full of water or looked like they were unearthed from an archeological site. Don't let this happen to your telescope's optics and electronics by following a few rules. First, don't store a telescope outside. No matter how protected you think it is under your patio, dust and water have a way of getting into the most amazing places. If you know the weather will be good (and trust us, you never know, and neither does your local meteorologist), you can keep a telescope in a protected area outside when you plan on using it frequently. But if you know you will not use a telescope for a few days, it is best to bring it inside. Don't listen to anyone who tells you otherwise, a telescope looks great in a living room. It's a wonderful conversation piece. No one will ask you about the philodendron bipinnatifidum growing in the corner, but everyone will inquire about your telescope.

Heat can also affect a telescope, especially the electronics and the drive motors and gears. The grease on the gears in a telescope mount can evaporate in high temperatures, so try to avoid direct sunlight, especially in hot environments. It seems obvious, but keep the telescope optics covered when you are not observing, and keep all the openings to the telescope (such as the focuser or visual back) capped when not in use to prevent dust and dirt and spiders and moths and other critters (trust us, if it fits, it will find a way in there) from finding a happy home inside your telescope.


The following are some of the most common problems new stargazers run into and the fixes for those issues.

I Can't See Anything Through the Telescope

One hates to overstate the obvious, but more than a few people have forgotten to take the cover off the telescope. Assuming this isn't the problem, the questions becomes, what is? The best test is to look through the telescope during the day. As Han Solo says in Return of the Jedi, "I think my eyesight is getting better. Instead of a big dark blur, I see a big light blur." So the question is do you see a big light blur through your telescope? If so, that is--as Captain Solo has pointed out--a step in the right direction, and you can skip to the next troubleshooting section below. If everything is still dark, be sure there isn't a cap on the inside or the eyepiece or diagonal that it blocking the light. A common mistake is also to try looking through a Newtonian reflector backwards. Remember, if your telescope is a Newtonian (the eyepiece sticks out the side of the tube), the eyepiece end points toward the sky.

Everything Is Blurry Through the Telescope

If you can see something through your telescope, but it is just a big amorphous blob, there is at least light coming through, which is a good first step. If you are testing your telescope during the day, be sure it is not pointed at something too close. The closest most telescopes can focus is about 30-50 feet away. Also, keep in mind that on some telescopes, especially Schmidt-Cassegrain telescopes, the focus travel can have quite a range. You may have to turn the focus knob 20-30 times to reach focus. If these steps don't work, be sure there are no other accessories between the eyepiece and the telescope (other than a diagonal, if required). Some inexpensive telescopes include Barlow lenses that, if installed in the wrong place between the eyepiece and scope, may prevent the telescope from reaching focus.

The Image is Upside-Down

There are three possible causes for this. One, the image is rightside-up and you are upside-down, but this should be apparent (one would hope). Secondly, you could have a Newtonian telescope. A Newtonian has the eyepiece sticking out the side of the tube, near the front of the telescope. This type of telescope is ideal for stargazing, but does give an inverted image, making terrestrial viewing difficult. Unfortunately, there is really no fix for this--except standing on your head (see cause number one). Lastly, a telescope such as a refractor or Schmidt-Cassegrain cangive a correct image for terrestrial viewing. However, if the diagonal is rotated so the eyepiece is horizontal, the image will flip. The eyepiece must be kept straight up and down for the image to appear rightside-up.

The Telescope Won't Stay Still

A well-built telescope should stay put when you aim it somewhere. Some inexpensive models tend to be a bit wobbly, and unfortunately there isn't much you can do about this (other than upgrading to a better scope). For telescopes that should hold still but won't, the most common problem is balance. It is critical to properly balance a telescope for stability and tracking. If you point a telescope to one part of the sky and it slowly drifts from that position, odds are it is unbalanced and extra weight is pulling it out of alignment. See the page on Balancing a Telescopefor more details on this procedure.

In addition to slowly drifting, a telescope may vibrate excessively. Again, this shouldn't be too much of a problem with a good quality telescope. Setting up on a stable surface is important. Decks and flat rooftops make convenient places to observe from, but they tend to be unstable. Vibration suppression pads are made to be placed under the tripod legs of a telescope to dampen vibration. Also, adding weight to a tripod can help stabilize a telescope. Try hanging a weight from the center support of the tripod, or filling the tripod legs (if you can get to the inside) with sand.

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