What is the difference between refractor and reflector

For refractors, consider getting an achromatic or apochromatic lens. For reflectors, look for true parabolic mirrors and high-quality engineering. For visual astronomy, we generally recommend you get the largest aperture you can afford. As long as the telescope is a good fit for your needs in other ways — especially in terms of size, weight, portability, and ease of use.

Remember: The amount of light a telescope can collect is related to the square of the aperture size. For refractors, as the diameter of the aperture increases, the cost and bulk of the lens increases exponentially faster.

For this reason, most amateur astronomers prefer reflector telescopes for deep-sky visual astronomy. In fact, when it comes to large aperture sizes, reflectors are pretty much the only game in town for the average amateur. Make sure you know the telescope size that you can best handle. Bottom line: For deep-sky visual astronomy, there is no substitute for a large-aperture reflector telescope.

Most amateur astrophotographers prefer the simplicity of a high-quality apochromatic APO refractor telescope. There are also some great reflector options for astrophotography, but refractors have some key advantages. For visual astronomy, you do need a large aperture, because you need to get as much light as possible into the telescope all at once so you can see the target with your eyes.

However, with astrophotography, what you really care about is the amount of light per pixel — so the speed of the telescope becomes more important. And remember, you get the focal ratio by dividing the focal distance by the aperture size. So, for astrophotography, a fast 80mm APO refractor can outperform a larger but slower telescope.

Second, with astrophotography, smaller telescopes are often preferable because they are lighter. And lighter telescopes require less costly mounting systems.

Astrophotography mounting systems can get expensive… in a hurry. In fact, for astrophotography, the mount is arguably just as important as the telescope. Astrophotographers need to be able to take multiple long-exposure shots while keeping the telescope perfectly trained on their target. Smaller telescopes are much lighter and therefore can follow a moving object more cleanly than its bigger brothers and sisters. A comet moving across the night sky can be followed automatically if you have the right settings.

With a lighter telescope, you can use a less expensive mount and still get smooth control over the movement. Bottom line: Apochromatic APO refractors are fantastic for astrophotography.

There are plenty of fantastic small refractors available, designed with special lightweight tubes for traveling. Both Celestron and Orion make excellent entry-level traveling refractors. These telescopes are versatile, drop-dead easy to use, require zero maintenance, and can fit in a backpack. People have debated this question since … well, pretty much the invention of the telescope.

But not quite, since refractors were invented about 50 years before reflectors. Hopefully this article has helped you see there are clear pros and cons for both types of telescopes. Bottom line: There is no single best telescope type. Each has its place in astronomy. Also, if you liked this article, please share it using the social media buttons below!

As an Amazon Associate we earn from qualifying purchases. Amazon and the Amazon logo are trademarks of Amazon. We do not specifically market to children under Skip to content Skip to primary sidebar. Contents Basic Features: Reflecting vs. Refracting Telescope Summary: Which is Better? Refracting Telescopes. Category Winner Why?

For smaller telescopes, refractors still offer good value. This is not a big issue for astronomical purposes, as there is no up or down in space. However, this does render this type of scope impractical for terrestrial observations. Because parabolic mirrors have fewer surfaces and are thus easier to make than lenses, combined with the cheapness of the relatively common plate or borosilicate glass used in most astronomical mirrors, reflectors can be made for very low costs and at very large sizes.

Most reflecting telescopes for amateurs, especially large ones, are on what is called a Dobsonian mount, which dispenses with a tripod altogether and uses simple friction-based movements. These mounts are cheap, durable, and rock-solid, and are easily scaled to large sizes. A scope up to 14 or 16 inches will fit even in a sedan. This makes assembly more complicated and the telescopes more expensive, but the ease of transport more than compensates for this minor drawback.

All optical devices represent a set of compromises. As such, there is no best design. A key advantage of the refractor is that there is no secondary mirror obstructing the aperture in the middle. However, due to the laws of physics and diffraction, this obstruction also smears the image very slightly and results in a loss of contrast along with some fine detail.

Refractors tend to hold the alignment of the elements in the optical path because the front lenses are rigidly mounted. Refractors are fairly maintenance free making them popular for new astronomers. This may be another reason that the refractor design is incorporated into binoculars and most spotting scopes. The primary disadvantage on an aperture-for-aperture basis of the refractor is the aforementioned problem of chromatic aberration.

This is in essence only solved by spending more money or increasing the focal ratio, the latter of which makes for an unwieldy instrument with a narrow field of view. The other disadvantage is, again, simply the cost. The main advantage of the Newtonian reflector design is that it is simply cheaper to manufacture quality mirrors than lenses, especially as they get large. Mirrors, as they reflect rather than refract, never split incoming light rays the way a refractor does.

As a result, there is no need to worry about chromatic aberration. Coma results in stars that are near the outer edge of the field of view becoming blurry and appearing to have a comet-like tail or cross shape. The other factor with reflectors is the need for regular collimation. The typical Newtonian reflector has a primary mirror that is mounted in such a way that the mirror can be moved to align the optics. Alignment should always be checked every time the telescope is set up, but it is a relatively easy process if it does indeed need correction.

The bigger the mirror is, the brighter the objects appear in the eyepiece. However, a big mirror could quickly emphasize the optical aberrations of the telescope. Theoretically, getting a perfect round dot of a star requires having a newtonian reflector made with a hyperbolic primary mirror.

In fact, such a mirror is relatively expensive and telescopes manufacturers choose rather a parabolic mirror instead, far simpler to build. However, a parabolic mirror is facing a defect: the coma aberration which deforms and elongates the star around the fields of view. More often, the low-cost manufacturers do not use nor a hyperbolic neither a parabolic mirror but a spherical mirror. With such a geometry, you will never manage to focus perfectly the image of a star with your reflector, because of spherical aberration ; a delicate situation considering that astronomy requires to observe and photograph faint and diffuse celestial objects.

Reflector telescopes are mainly open telescopes , meaning that the mirrors are exposed to the air, humidity and dust. This is why they require to be manipulated with precision and attention. For example, a mirror frequently exposed to this harsh environment could be less reflective within years, or put it in a different way, its ability to reflect light decreases. To this point, the cleaning of the mirror is highly recommended, paying extreme attention to the fragile optical parts while dismounting the telescope.

A key element not to be forgotten with a newtonian-like telescope is the necessity to collimate it. This procedure allows you to perfectly adjust the alignment of the telescope and must be done before each observation or astrophotography session.

This should be ideally carried out each time you observe or start an astrophotography session. Finally, reflector telescopes are first choice instruments when you want to collect the most light as possible.

But the side effects are that you will need to know in details the optical system and should not be shy when you will have to modify or clean the mirrors, as mentioned above. The principle of keplerian telescope is very similar to a monocular. The light goes through the front lens, key element making the light beams.