Refractor Telescopes - What You Need To Know
A telescope is an optical instrument used by astronomers to observe the night sky. Of course, these telescopes come in different shapes and sizes, and surprisingly, their designs too. The two most popular ones are the Refractor model and the Reflector model. This article will help you have a better understanding of the Refractor design.
History
Refractor, also known as refracting, is the earliest telescope model, dating back to the year 1608, when a spectacle maker in the Netherlands unsuccessfully tried to patent one.
Design
All refractor telescopes work the same way by gathering parallel light from space, bending them so they meet at a point which is called the focus point and finally reach the eyepiece which turns them nearly parallel light again. This is why modern refractor telescopes often include a prism, which is a device to correct the image orientation.
A few refractor telescope designs include:
Galilean: First known telescope design. Image produced are non-inverted due to the lack of intermediary focus. Used to observe objects include Moon craters, some Jupiter moons, and Venus.
Keplerian: An improvement from the Galilean design. Instead of a convex lens for eyepieces, this design uses concave lens. But due to its simple design, a really long f/ratio is needed, which results in really long tubes.
f/ratio = Focal length of telescope / Apeture of telescopeAchromatic: To solve the problem with long f/ratio, achromatic lens was invented, allowing shorter designs with shorter lengths while minimizing Chromatic Abbreviation ( Explanation below )
Advantages and disadvantages
Advantages
Because of all – sealed design, Refractor telescopes are less likely to gather dust from the environment. This reduces maintenance needed.
Refractor telescopes are famous for their uncomplicated design, which is perfect for beginners and early enthusiasts.
Disadvantages
Due to the lens-based objective, many budget telescopes may suffer from Chromatic Abbreviation – an effect resulting in bright halos around bright objects. This effect is more noticeable in low f/ratio telescopes.
Because of the components, Refractor telescopes are usually more expensive than other types of telescopes, considering Aperture size.
Conclusion
Refractor telescopes are one of the oldest and most reliable designs in astronomy. Despite being simple in structure and easy to use, they can still deliver sharp and detailed images, especially in higher-quality models. However, issues such as chromatic aberration and higher cost per aperture can make them less practical for large-scale observing compared to other designs like reflectors. Overall, refractor telescopes are an excellent choice for beginners and those who value durability and clear optical performance.