Using Your First Telescope - Part One: Tips for Happy Stargazing
Once you have your new telescope, here are tips we’ve found useful to ensure a happy experience on your first night out, and on what we hope will be many enjoyable nights under the stars after that.
Read the Instructions!
Yes, we know it’s exciting to just get it all unpacked and assembled! Stop! It is a good idea to read through the instructions, noting specific tips and assembly steps that might apply to your telescope, but not be obvious to the novice. PDF versions of manuals are available at the manufacturers’ websites, usually under Support.
Set Up First Inside
Don’t attempt the initial assembly at night in the cold and dark. Set up your new telescope inside first, so you can see what you are doing in comfort. With many telescopes most of the assembly steps need be done only once. As shown, Dobsonian mounts, which ship in a “flat pack,” require the most initial work.
After that, with most telescopes, the mount and tube can be stored assembled, and carried out as a single piece, or at most, only the tube might need to be placed onto and removed from the mount or tripod with each use.
Align the Finder
Follow the telescope’s instructions to line up the included finder aid (likely a little telescope or a red-dot finder) so it is aimed at the same spot as the main telescope. As shown above, do that by using the telescope outside by day to aim at a distant treetop, power pole, or any identifiable feature a few hundred metres away.
Centre the object in the main telescope used at its lowest power (see below), then adjust the finder (they all have adjustment screws) so the same object is also centered on the finder’s red dot or cross-hairs. Doing that by day will avoid no end of frustration at night, making it easy to aim the telescope.
It is also an essential step for aligning all GoTo telescopes. See Using Your First Telescope — Part Two: Aligning a GoTo Scope.
Focus by Day
As part of the finder alignment, focus the telescope at low power on your distant target. Unlike at night, you’ll be able to easily tell when the image is sharp and in focus.
If your telescope is a refractor you’ll need to use the “star diagonal” that came with the telescope. It allows for convenient right-angle viewing when the telescope is aimed up to the sky. Without it, the telescope likely won’t reach focus.
Practice switching eyepieces to change the power, which usually requires refocusing. You’ll see how at high power, the image will be more magnified but dimmer. And it will bounce around more easily as you touch the telescope.
Switch back to low power, refocus on a distant object, then leave the telescope focuser at that position. You’ll be pre-focused and ready to go for seeing things in the night sky.
Note: Stars should look like sharp and tiny points. If they look like large bloated disks, your telescope is out of focus!
Keep the Power Low
Even at night, always use the lowest power eyepiece first (the one with the largest focal length number, likely 25mm) to help you find and centre things. Bump up the magnification (perhaps by switching to the 10mm eyepiece) only after the target is centered. Even then, high power will be useful mostly for the Moon and planets.
Yes, the View is the Wrong Way Around
Your daytime tests will likely reveal that the image is either upside-down (in most reflectors) or as shown, flipped left-to-right (in most refractors).
Don’t worry, there’s nothing wrong with your telescope. All astronomical telescopes are like that; the optics needed to erect the image would distort and dim the images of celestial targets. So most astronomical telescopes don’t include such optics.
And other than the Moon, you won’t be able to tell if any celestial object is right-side-up or not anyway!
Yes, it’s cold outside. However, keeping warm by looking through a window won’t work – the view through the glass or even through an open window will be too blurry. The telescope must be outside and cooled to the nighttime air temperature before it will give the sharpest views. Then don’t look over heat sources like rooftop vents.
Look at the Moon
As we show above, during the two weeks after a New Moon, your first evening target should be the Moon. It will never fail to impress! You won’t believe it can have so many craters, all from impacts of asteroids long ago.
Equatorial Mount Moves
The most complex mounts to master are what are called “German equatorial mounts” because the design was invented by a German astronomer. They can track the sky easily and, if equipped with a motor, automatically. But only if they are set up correctly.
As per the telescope’s instructions, the mount should be adjusted so the angle of the “polar axis” is equal to your latitude, a set-once-and-forget adjustment.
After that, every night simply place the mount so that its polar axis aims due north, toward Polaris, the North Star. The Pointer stars of the Big Dipper’s Bowl point to Polaris.
Use the altitude (up-down) and azimuth (left-right) adjustments on the base of the mount (shown) to fine-tune the aiming of the polar axis toward Polaris.
Find objects by moving only the other two rotation axes that swing the telescope in the north-south direction (called “declination”) and in the east-west direction (called “right ascension”). The above image shows the mount polar aligned, but the telescope itself is aimed to the south, where many targets will be.
Here the telescope is aimed so it is looking northeast toward rising objects.
Here the telescope is aimed so it is looking northwest toward setting objects.
Note that in all cases, the mount’s polar axis always remains aligned pointed to the north. Its angle and direction remains fixed.
To find new objects with this type of mount beginners sometimes make the mistake of always adjusting the polar axis angle, or picking up the mount and turning it. No! The base of the mount stays where it is — it is the tube that turns to find new targets.
Chapter 10 of The Backyard Astronomer’s Guide by Terence Dickinson and Alan Dyer provides many more detailed tips and instructions for setting up and using your first telescope.