A reflector telescope, as the name implies use mirrors to reflect the light the telescope gathers to the eyepiece located on the side of the scope near the front.
Sir Issac Newton is credited with the invention and this type of telescope became known as the “Newtonian reflector”.
A Newtonian has a primary mirror located at the base of the telescope tube and a secondary mirror at the top of the tube which reflects the image to the eyepiece.
Making a mirror for this purpose is cheaper than grinding a glass lens so reflectors are cheaper per inch(or millimeter) than refracting telescopes.
The biggest advantage to a reflector is the fact that mirrors are cheaper than lenses. As a stargazer you want the most light gathering ability you can get for the price you are willing to pay.
Aperture is the most important element in backyard stargazing. You can get 1.5 to 2 times the aperture with a reflector as opposed to a refractor.
This leads directly to the next advantage of reflectors.
Very good at seeing deep-sky objects such as galaxies, star clusters, and nebulae.
With a larger aperture dimmer objects and more distant sights become visible.
Reflectors do not have chromatic aberration caused by glass lenses.
Reflectors are quite portable, especially on Dobsonian mounts. They readily break-down into 2 manageable pieces and can weigh less than 50lbs fully assembled.
Easier on the back as you don't bend as far since the eyepiece is located on the upper side of the tube.
With its larger aperture you can transition from Solar System views as a beginner to deep-sky easily as you gain experience without needing to purchase a new scope.
There are some disadvantages to the reflector telescope as well.
Reflectors are open-ended, this can cause problems if you aren't careful. Dropping something into the open end could damage your mirror.
This openness also means that the inside of the tube and the mirrors will need to be cleaned periodically.
Transporting and moving the tube can cause the mirrors to become misaligned.
A misaligned set of mirrors will cause blurred images. This problem is readily fixed by a process called collimation. You can do this yourself in a matter of minutes when needed.
Check out this video from Orion Telescopes showing how this is done...collimation video.
In light polluted areas reflectors will magnify the surrounding light as well as the objects you are stargazing. This will wash-out you images somewhat.
Contrast is not as good in a reflector as opposed to refractors because of the secondary mirror. As you reflect an image some light and contrast is lost.
The braces of the secondary mirror known as “spider vanes” can sometimes hide an object such as a binary star component.
As refractors have chromatic aberration, reflectors have coma.
Coma is the effect of the curvature of mirrors. The objects near the edge of the field of view will take on a slight triangular or wedge shape. Objects in center view are not effected by this.
I personally am a fan of reflector telescopes over refractors. They are simple to set-up and use and with a Dobsonian mount can be ready to go in minutes.
There are things to consider, especially if your primary viewing area is heavily light polluted.
Cleaning and collimation are simple chores once you get the hang of them.
In my opinion the advantages of a large aperture outweigh all the disadvantages and even the advantages of the refracting scopes.Celestial Solar System › SCOPES › reflector telescopes