![]() ![]() It's also one of the most popular types of telescopes available today. Their non-movable lenses make for a sturdy design that doesn’t need much maintenance beyond the occasional cleaning. Still, whether a doublet or triplet, refractors are a solidly built type of telescope. Most low-cost refractors are “doublets,” which may have color fringing, whereas “triplet” refractors are designed to eliminate this issue.Įxample of chromatic aberration, a common problem with lower cost refractor telescopes Also known as chromatic aberration, color fringing is when the various colored wavelengths of light get split from each other and arrive at slightly different angles, showing up as an image with distinct coloration at the edges. Most refractors available for purchase tend to be smaller than other types of telescopes, making refractors one of the most portable types of telescopes on the market.ĭepending on the type of telescope lenses used for the optics, you may encounter visible color fringing at high magnifications. The length and size of the lens of a refractor, combined with the fact that large lenses can be difficult and expensive for glassmakers to manufacture with high quality and accuracy, means that larger refractors can get rather expensive. The larger the lenses in a refracting telescope, the longer the optical tube has to be to bring the image into focus. They are usually long relative to their overall size, as light must flow in a straight path through the telescope tube to the eyepiece or camera. We just use other mirrors to flip it back.Refractor Telescopes utilize specially designed lenses to focus incoming light into an image for you to see with your eye or capture with a telescope camera. Have you ever looked into a spoon and noticed your reflection is upside down? The curved mirror in a telescope is like a spoon: It flips the image. Also, since mirrors are one-sided, they are easier than lenses to clean and polish.īut mirrors have their own problems. It is much easier to make a large, near-perfect mirror than to make a large, near-perfect lens. So the mirror just has to have the right curved shape. Light is concentrated by bouncing off of the mirror. A bigger mirror does not also have to be thicker. Unlike a lens, a mirror can be very thin. It would be like looking through a dirty window.Ī telescope that uses mirrors is called a reflecting telescope. Any flaws in the lens will change the image. Also, as they get thicker the glass stops more of the light passing through them.īecause the light is passing through the lens, the surface of the lens has to be extremely smooth. Heavy lenses are hard to make and difficult to hold in the right place. If you want to see far away, you need a big powerful lens. People with especially poor eyesight need thick lenses in their glasses. In a telescope, it makes faraway things seem closer.Ī simple refracting telescope uses lenses to make images bigger and more visible. In eyeglasses, this makes things less blurry. It’s hard to make a perfect mirror, but it’s even harder to make a perfect lens.Ī telescope made with lenses is called a refracting telescope.Ī lens, just like in eyeglasses, bends light passing through it. If they do have such problems, the image gets warped or blurry and is difficult to see. They can’t have any spots, scratches or other flaws. That means the mirrors and lenses have to be just the right shape to concentrate the light. The optics of a telescope must be almost perfect. That light is what we see when we look into the telescope. Light is then concentrated by the shape of the optics. ![]() The bigger the mirrors or lenses, the more light the telescope can gather. To do that, the optics-be they mirrors or lenses-have to be really big. The mirrors or lenses in a telescope are called the “optics.” Really powerful telescopes can see very dim things and things that are really far away. So why do we use mirrors today? Because mirrors are lighter, and they are easier than lenses to make perfectly smooth. The first telescopes focused light by using pieces of curved, clear glass, called lenses. Most telescopes, and all large telescopes, work by using curved mirrors to gather and focus light from the night sky. A telescope is a tool that astronomers use to see faraway objects. ![]()
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