6/22/2023 0 Comments Newtonians![]() Dobsonian reflector telescopes (credit: Meade Corp.) Dobsonian Reflectors Another advantage of Newtonians: because mirrors reflect all colors of visible light exactly the same, reflecting telescopes have no chromatic aberration. But it’s not a big deal if the focal ratio is bigger than f/6 or so. This makes stars appear wedge-shaped at the edge of the field of view. Newtonians also have a type of optical aberration called “coma”. Newtonians also tend to be bulky, with tube lengths of 4-5 feet or more. The adjustment is not complicated, but it takes a little practice. Newtonian reflectors occasionally require adjustment of their optical alignment– especially if the scope gets bumped. ![]() A top-of-the line 4-inch refractor costs as much, or more than, a 12-inch Newtonian reflector, yet the reflector has 9 times the light gathering capability. A smaller secondary mirror reflects light out the side to an eyepiece. The front of the tube is open the mirror sits at the back of the tube. Some homemade reflectors even use glass from the discarded portholes of a ship! The layout of a Newtonian reflector. And since no light passes through a mirror, less expensive glass is used. įor a given aperture, Newtonian reflectors are generally the least expensive telescope because, unlike the lenses of a refractor, only one surface of a mirror needs careful figuring and polishing. His immensely practical design, now called the Newtonian reflector, is the main type of purely reflecting telescope in use today by amateur astronomers. He used a second small diagonal mirror to direct light out the side of the telescope to an eyepiece. Isaac Newton gets credit for inventing the first reflecting telescope in the late 17 th century. Reflecting telescopes (or reflectors) collect light using a curved mirror at the rear of the main tube rather than a lens at the front end. But hopefully, you now have the tools to know which one is the better fit for you.A Newtonian reflector telescope on an equatorial mount (credit: Skywatcher). ![]() Maksutov-Cassegrain pros and cons ProsĪs you can see, both types have many advantages and disadvantages. Newtonians on the other hand only take 5 to 10 minutes to do so. Depending on where you store them, you might want to take them out an hour before you use them to give it time to acclimate. Maksutovs take considerably longer to acclimate. This means that if you bring them outdoors on a cold night from storage where it might have been warmer, it will take a bit for the telescope to settle to ambient temperature. Telescopes need to be at ambient temperature in order to perform at their best. This process is called “collimation” and while it sounds intimidating, anyone can do it with a little bit of practice.Īgain, they both have pros and cons in this area because Newtonians do require collimation every few months, but it is easy to do, while Maksutovs need to be collimated maybe once every couple of years, but they are trickier to collimate. If you have never used a telescope or if you are coming from using a refractor that never or almost never needs maintenance, you might not know that every once in a while the mirrors in the telescope need to be re-aligned or they’ll start showing small optical errors. The following diagrams show how each transmits the light.Īnother important thing to consider is collimation. The light travels back and forth across the tube 3 times thanks to the secondary mirror at the end of the tube. ![]() How is that even possible? Well, that’s because the design of Maksutovs is very clever. On the other hand, MAKs pack a longer focal length into a smaller tube and a more compact design. The light only travels through the tube once, which makes the focal length of a newt almost the same as the length of its tube. Newtonians transmit light by using a long tube and reflecting the captured image into a second mirror that sends it to the eyepiece. Differences between Maksutov-Cassegrain and Newtonian/reflector telescopes To keep things short we will sometimes refer to Maksutov as MAKs and Newtonians as newts. So here are the differences, pros, and cons of each other to help you make a more educated choice. When you compare them to refractors or Dobsonians, they have clear advantages and disadvantages, but when you compare them to each other, things can get confusing. The options can get overwhelming.īut one of the hardest pairs to choose from is when you face Maksutov-Cassegrain vs Newtonian telescopes because they are very similar to each other in many categories. ![]() There are so many types to choose from: Refractors, Newtonians, Dobsonians, various types of Cassegrains, etc. One of the decisions that can be harder to weigh when it comes to choosing a new telescope is what type of telescope is best for your particular needs. ![]()
0 Comments
Leave a Reply. |