Path of light rays through a reflecting telescope (©2019 Let’s Talk Science based on an image by Krishnavedala via Wikimedia Commons). These lenses can be adjusted to focus the image. In a refractor, the eyepiece may contain several lenses. It’s a piece you put in the telescope to look through with your eye. The eyepiece is exactly what it sounds like. Modern refractors have a second tube that contains the eyepiece or ocular lens.
In other words, it’s the lens at the end where the light comes in. What are the parts of a telescope?Ī refractor is made up of a long tube containing lenses. Their lenses would be very heavy and their tubes would need to be very long. Most modern observatories use reflectors because their telescopes are so huge. Reflectors, on the other hand, use mirrors instead of lenses to reflect light. It's the type of long telescope which you might imagine old-time astronomers, like Galileo, using.
Let's consider a basic optical telescope. On the other hand, refracting telescopes are used more in everyday items like binoculars and camera lens systems due to their straightforward design and lower construction costs.ġ.Reflecting telescopes use mirrors while refracting telescopes use lenses.Ģ.Refracting telescopes require a much purer material than reflecting telescopes.ģ.Reflecting telescopes can be made much larger than refracting telescopes.Ĥ.Reflecting telescopes suffer less from aberrations than refracting telescopes.ĥ.Reflecting telescopes are used more for astronomy while refracting telescopes are used more for photography.The world's largest refracting telescope is the Yerkes Observatory 40-inch Refractor (Source: Kb9vrg via Wikimedia Commons). Reflecting telescopes are used more and more in astronomy due to their ability to see much farther and much clearer. Large, refracting telescopes often introduced distortions in the image either due to imperfections in the material or the sag caused by the weight of the lens itself.Ĭurrently, reflecting and refracting telescopes have their own roles to play. Reflecting telescopes gained popularity as it became more expensive and difficult to create large, refracting telescopes. Mirrors can also be made relatively cheap making it more feasible to build large arrays. Reflecting telescopes can be made as big as you want since the mirrors can also be made in smaller segments which are then put together to perform one large mirror. With lenses, the maximum size is limited to about one meter, largely because of the problems stated above as well as the skyrocketing costs. Any imperfection in the material beneath the top layer is already unimportant.Īnother key advantage of reflecting telescopes is how big you can make them. In comparison, the mirrors needed in a reflecting telescope are much easier to produce as only the reflecting surface needs to be absolutely perfect. It may be easy to do with small lenses, but the difficulty exponentially increases as you increase the size. One limitation is the need to produce glass lenses that are absolutely devoid of bubbles or any foreign materials. As technology improved, however, its limits began to show.
Refracting telescopes gained early ground because they were far easier to create in the days prior to modern technologies. In contrast, a refracting telescope uses lenses that focus the light as it travels towards the other end. The main component in a reflecting telescope is a mirror where the light will bounce off and is then focused into a smaller area. The distinction between the two is in how they manipulate the incoming light in order to magnify the image. When it comes to telescopes, there are two types the reflecting and refracting telescopes.
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