You And Your First Astronomy Telescopes



Ok lets learn about astronomy telescopes. You feel you're ready for your first telescope, good. First there are things you need to figure out about you or whomever is going to mainly be using that telescope.

Even before setting a budget these questions should be answered .

Who will be using the telescope most often. Is it a younger child? Then maybe you need a more rugged scope to protect it from bumps and shocks. Telescopes are a precision optical instrument and need care.

Do you or the intended user take care of things? Astronomy telescopes can be pricey. You want to make sure it will last a few years at least until you're ready to upgrade. Think about this seriously, especially if buying for a child. You don't want to have to replace a scope because of carelessness.

Where will the scope be used most often? Do you have a favorite spot? Is your watching place easily accessible? Will you need to load the scope into your car and drive some place and then set it up?

Or will you be able to mount the scope and keep it ready? How much weight can you comfortably carry around?

Remember the best astronomy telescope is one that gets used the most often. If it's to heavy or to complicated to setup and move to your viewing spot it probably wont get used or enjoyed as much.

Then think about how the scope will be used. What will you be looking at? A good scope will allow you to see various objects in space well, but each type has pluses and minuses, and may be slightly better at one phase of stargazing than another.

So decide what your main targets will be, especially for younger children, and then choose a telescope within your budget that best suits your main area of interest.

Choosing Your Astronomy Telescope

Now it's time to talk about the scopes. Most people think, and a lot of sales' copy emphasize, magnification or power.

This is not the place to begin. The most important astronomy telescope feature is aperture size. A telescope needs to gather light to be effective and the aperture or lens size is how this is done. A larger aperture means more light gathering ability. So... buy the largest aperture size you can afford all things considered.

Power or magnification is determined by the focal length of the telescope tube divided by the focal length of the eyepiece you are using. So if the scope has a focal length of 300mm and the eyepiece has a 4mm focal length then the power is 75 times (300/4=75).

Just remember that as power or magnifying increases, image sharpness and brightness decreases. To increase magnification you take the same amount of light and spread it over a larger area.

Generally at double power the image will be 1/4 as bright and 1/2 as sharp.

Maximum power should be about 50 times the aperture size in inches or 2 times the aperture in millimeters. This means a 6inch aperture should use at most 300 times magnification.

Also "seeing" or atmosphere turbulence will have an effect on how well you can see objects. Turbulence in the air caused by radiating heat as the ground and surrounding areas cool down from the day's sun can cause loss of visibility.

This air turbulence will cause swimming and shimmering of objects as you try to see them. Some nights will be worse than others. You can reduce this distortion effect by using lower magnifications.

Check the "seeing" by looking at the stars, a lot of twinkling means more distortion in the air.

Observe the star Megrez(magnitude 3.4) to see how much can be seen that night. Megrez is the star that connects the handle to the dipper in the Big Dipper asterism.

Also when you get to your spot and get set up take about half an hour or so to let your eyes adjust to the darkness.

This will expand the pupils and allow your eyes to gather more light and see better.

If you are using star charts or otherwise need light to see, use a red light or a flashlight covered with red cellophane so as not to ruin your night vision.

Don't Forget The Mount

You need a good quality mount or tripod. the alt-azimuth is the cheapest kind and most that come with your scope will do the job, just try to be sure it's not low quality.

With the alt-azimuth mount you will need to move the scope left/right and up/down to track objects.

As you advance you may want to get a motorized mount. Eventually you will want a dobsonian or equatorial type mount.

Now let us look at different types of astronomy telescopes.

Astronomy Telescopes Refractors Astronomy Telescopes Reflectors

For begining stargazers please refer to this page about realistic expectations when looking through your new telescope: stargazing for beginners

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