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Starwatch: Telescope dos and don’ts

May 11, 2019 GMT

I usually write about telescope dos and don’ts around the holiday season, but I thought for a change I’d write about it now. After all, it’s a lot more comfortable this time of year for stargazing.

The tradeoff is that the skies don’t get dark until much later in the evening. If you’re like me, you’re not a big fan of reading instructions, but following the rules of telescope observation is important. I want you to enjoy that new, or older telescope for that matter, and not have it wind up being stuffed away in a closet or attic.



You will go blind in that eye permanently. That’s all that needs to be said.

Always use your telescope outside.

Poking your telescope out of the window just doesn’t work. The wave of heat or cool leaving your house will definitely interfere big time with what you’re trying to view. It’s always important to set up your telescope outside and let it sit out there for a good half hour to forty five minutes before you start using it. Also make sure any eyepieces you’re using sit outside ahead of time as well. In my mind, this is the number one rule for nighttime observation, and for good reason. The lenses and/or mirrors in your scope have to acclimate to the outside temperatures or there’s a good chance you may get blurred images.

Set up your telescope on firm ground.

Avoid setting your scope up on any kind of wooden deck. No matter how well it’s built, or how solid it is, vibrations from your movements or anyone else with you will jingle around your scope just enough to drive you crazy. Always set your telescope up on solid ground or at least a cement or stone patio.

Sync your finder telescope or device with your main telescope.

In all my years of putting on Starwatch programs, the number one complaint from folks who buy a telescope is that they can’t find anything with it. Maybe the moon and few bright planets, but that’s it. It’s very, very important that whenever you set a telescope up for viewing, you must make sure the finder scope or device (such as a small laser) are aligned or synced with each other. In the normal course of scopes being moved around finders can easily get bumped out of alignment. The best thing to do, every time you use your telescope, is to first put a low power magnification eyepiece in your main scope, and aim your scope at a prominent object such as a flag or church steeple on the horizon. Once you have your land target centered in the main scope, adjust the screws on your smaller finder scope or your laser so your object is centered on the same land target as well. Most good finder scopes have crosshairs in them to help with this.


Once that’s done you’ll find it much easier to find celestial targets by first getting them in your finder scope. If you’ve synced it up properly you should see your celestial target in the main scope, or least be darn close.

Start with low power magnification eyepieces.

When you look at something through your scope start out with a high focal length, low power magnification eyepiece. The focal length should be labeled on the eyepiece. 25 to 40mm focal lengths work best to start out with. If you’re not sure which eyepiece is low magnification, it’s the one with the wider lenses. Then you can start to use higher power, lower focal length eyepieces if you want. Don’t be discouraged if your target loses some of its clarity with increasing magnification. This is normal.

Look high enough.

Make sure your celestial target is high in the sky if possible. A third of the way from the horizon to the overhead zenith or higher is best. When you try to observe anything close to the horizon you’re forced to peer through a thicker level of Earth’s atmospheric shell, which has a most definite blurring effect! Also keep in mind that even if the skies are clear, some nights will be better than others, depending on how high the winds are in the upper atmosphere. High winds aloft have a noticeable blurring effect no matter how high or low you observe in the sky. This is what amateur astronomers call “bad seeing” conditions. There’s nothing you can do about that except to try looking on another night. A great website to help you determine the seeing conditions is “Clear Sky Clock’. There are others as well.

Take long looks.

This is where it takes some discipline. Try to take long continuous views through the eyepiece of your scope, even 10 to 15 minutes at a time, especially with the planets. That will allow your eye and brain to adjust to the light level in your eyepiece, which will allow you to see more subtle details. During that time you’ll no doubt have to shift your telescope to keep up with Earth’s rotation. Nothing stands still in the sky. Some telescopes have motors to help you do that automatically, but you can also successfully do it manually.

Above all, be patient!

Read as much of the instructions that come with your telescope as you can and remember, you don’t have to conquer the whole universe in one night or even one year. Amateur astronomy is meant to be a life long passion! It certainly is for me.