Loading Products...

Newtonian Telescopes, invented by Sir Isaac Newton, are often less expensive than other telescopes with the same size aperture. They typically provide wide field views due to their short focal length and are very efficient with light gathering because of their fast focal ratios. Newtonians, as they are commonly called, are generally much more portable than the larger Dobsonian Telescopes, which have the same optics design but are mounted on large rotating bases.

Newtonians also make for fantastic imaging telescopes due to their fast focal ratios. Unlike refractors, Newtonian telescopes do not suffer from chromatic aberrations since they use mirrors instead of lenses to focus light. While Newtonian telescopes excel at Astrophotography they are also great for visual astronomers as well. Take a look below to see the pros and cons of the Newtonian Telescope design.


Advantages & Disadvantages of Newtonian Telescopes

Newtonian Telescopes-2
Newtonian telescope light path

Advantages of Newtonian Telescopes

One of the best things about their design is that they are very simple, yet still yield a large aperture for a lower cost. They have a very wide field of view so they can be excellent for imaging or viewing deep sky objects. Smaller apertures like 8 inches can be fairly portable, averaging around 30 inches in length. The cooldown time is also very short for these types of telescopes because they usually have an open tube. Lastly, they almost always have a short focal length which means they have fast focal ratios.

Disadvantages of Newtonian Telescopes

Because this design gives you wide-angle views and shorter photo times, you need very good quality eyepieces in order to get sharp images from one edge to another. Shorter focal lengths also make it harder to get high magnification. So if you plan to get a Newtonian telescope for visual astronomy, you should also plan to get some great eyepieces along with it. There is also some maintenance that needs to be done with these, especially after transporting them. This maintenance involves re-aligning the mirrors and is called collimation. Newtonian telescopes also suffer from something called "coma" where stars appear oddly shaped at the edge of images. This is usually self-corrected when the focal ratio is faster than f/6. A coma corrector can also be added to help minimize the coma effect.


Still have questions? We have answers.

The most common type of reflecting telescope the Newtonian design. We call it a Newtonian telescope because it was invented by Sir Isaac Newton in 1668. This simple, effective design was an improvement on the other telescopes of the day because it was easier to manufacture, allowed for a larger aperture than more sophisticated refractor telescopes, which resulted in brighter, more detailed views of the night sky. Newton's design also removed the chromatic aberration, or color fringing that was common in refractors of his time (and is still an issue with today's doublet refractors).

Newtonian telescopes consist of a concave primary mirror and a flat secondary mirror. Light enters the front opening of the telescope, travels past the diagonally mounted secondary mirror, eventually bouncing off the curved primary mirror. The curve of the mirror focuses the light onto the secondary mirror, which sends the image to your eyepiece or your astrophotography camera. Newtonian telescopes don't require lenses like a refractor telescope, though you will likely use a lens to control coma, especially for astrophotography, or to magnify views for visual use.

Newtonian Telescope Light Path

A Newtonian is a type of reflector telescope. Light is reflected within the telescope, flipping it upside down, just as your bathroom mirror flips images side-to-side. Newtonians typically include a spotting scope, which does not flip the image, helping you find your subject without needing to account for the image flip of the main telescope.

Newtonians feature roughly double the focal length, when compared to their physical length, because they work by reflecting light. Unlike a refractor telescope, which focuses light in a single plane, reflectors are able to fold the light by bouncing it off the primary mirror and secondary mirror. This allows for a greater focal length than the overall telescope length. The compact nature of a Newtonian telescope can be an advantage for those with limited storage space or those that like to take their telescope to their favorite dark sky location for optimal sky conditions.

When using an astrophotography camera and an equatorial mount, you can trade a smaller aperture for longer exposure times. When it comes to visual viewing, aperture is indeed king. This is because, the larger the area collecting light, the brighter and sharper your views will be.

Yes, all reflector telescopes require collimation, and a Newtonian is no exception. Shipping telescopes can cause collimation to shift, as can changes in temperature. We recommend you check collimation before use with a cheshire or laser collimator.

Collimating a telescope is not difficult with the proper tools. All it takes is a collimator and a few minutes of your time to achieve accurate collimation. Check out our blog post on collimating Newtonian telescopes.

Absolutely! Newtonians excel at many types of astrophotography when paired with a computerized equatorial mount and telescope camera. Depending on the focal length you choose, your Newtoinian telescope can excel at wide field, deep space, and even planetary astrophotography.

Keep in mind, the longer the focal length of your Newtonian telescope, the more accurate your tracking needs. So, if you choose to purchase a long focal length Newtonian, you'll need to be extremely accurate in your polar alignment to ensure that your stars stay sharp and round. Better yet, you can get a guide camera, in addition to your telescope camera, which will allow your equatorial mount to correct for any error or drift, so it can maintain accurate tracking throughout long exposures.