Top Astrophotography Telescopes of 2024

William Optics RedCat 51 APO f/4.9 WIFD Refracting Telescope

---

Apertura 75Q Refractor Telescope

---

Apertura 60mm FPL-53 Doublet Refractor

---

Askar V 60mm and 80mm Triplet Refractor

---

Askar 103APO Triplet Air-Spaced Refractor

---

Celestron EdgeHD 8 OTA

---

Apertura CarbonStar 150 Imaging Newtonian

---

Celestron 8" RASA

---

Honorable Mention

---

Glossary

Backfocus / Backfocal Distance / Backspacing

All optical systems have a point at which an in-focus image is formed, and for astrophotography it is at this location that the camera sensor should be placed. When the telescope is used without corrective elements, this is done easily with the focuser mechanism; and so long as an image can be brought into focus, optimal optical performance will be achieved. However with corrective elements, oftentimes there is a certain distance that the camera sensor needs to be placed away from the rear of the corrector for optimal performance. This will be listed as the backspacing or backfocal distance for the corrective element.

Carbon Fiber

Carbon fiber is a material that is composed of carbon atoms within a crystalline orientation. It is known for its incredible strength comparable to steel, though weighs much less (5x less to be exact). Because of this, the use of carbon fiber is highly beneficial in the realm of astrophotography, as this material provides a strong, yet lightweight, base for telescope and tripod construction.

Camera Rotator

A camera rotator is fitted onto the back of the telescope and allows the user to rotate their imaging equipment to find the desired photographic angle. These devices can either come manually operated or electronically operated. Electronic camera rotators are extremely beneficial for creating mosaics of the night sky, as they help you achieve precise camera orientation.

Corrector Plate / Corrector Lens

A corrector plate is a lens housed within front of the optical tube assembly on Schmidt-Cassegrains, Maksutov-Cassegrains, and Celestron RASA telescopes. This lens has the important job of correcting for spherical aberration, delivering improved views and images.

Collimation

Collimation is the process in which the optical elements of a telescope are aligned to deliver the best performance possible. In refracting optical systems, lens collimation is performed by the manufacturer at the time of assembly. In contrast, reflecting telescopes contain mirrors that are often bumped out of alignment. As a result, these types of telescopes require periodic collimation from the user to ensure peak clarity and sharpness. Various tools are available for collimation, such as laser collimation, Cheshire eyepieces, and collimation caps, just to name a few.

Coma

Coma is the comet-like appearance of stars near the edges of the frame. This occurs when light entering the optics focuses at different points around the corners of the image, causing an overlap of unfocused stars that present itself in a trailing manner.

Corrective Element

This refers to an optical accessory such as a field flattener, coma corrector, or reducer. These improve some facet of a telescope’s performance, such as optical distortions that might otherwise appear on the edge of the frame; or augments it, for example by providing a wider field of view.

Chromatic Aberration

Different wavelengths of light travel at different speeds based on the medium it occupies. When white light is exposed to glass such in a telescope or lens, blue light, red light, and green light slow at varying rates. This change of speed causes each wavelength to focus at different points along the focal plane, resulting in color fringing seen within the images taken.

EdgeHD Telescope

EdgeHD is Celestron's top of the line flat field aplanatic Schmidt-Cassegrain telescope series. You can buy a variety of apertures, from 8 to 14 inches, as an OTA or as part of a telescope/mount package. EdgeHD telescopes are great for visual use but they really shine for astrophotography. With a wide field of view that is three times flatter than a standard SCT, you will see beautiful, pinpoint stars across the entire field, even if you have a full frame (35 mm) CMOS or CCD camera sensor to satisfy.

#-Element (i.e. 2-element, 3-element, etc.)

When a refractor is described as having a 2-element, 3-element, 4-element, etc. optical design, that dictates the number of lenses within the refracting telescope. The number of elements also dictates how that refractor is classified: 2-element refractors are doublets, 3-element refractors are triplets, 4-element refractors are quadruplets, and so on.

Extra-Low Dispersion (ED) Glass

ED stands for “extra-low dispersion”, and is a type of glass designed to specifically reduce the separation of wavelengths when light passes through. Coatings of magnesium fluoride, zirconium dioxide, calcium fluoride, and titanium dioxide help bridge the gap between the different wavelengths of light, providing a singular focal point for all wavelengths. This helps reduce chromatic aberration and in turn provides heightened optical performance. Also, the more coatings on the lenses, the higher the transmission rate becomes for brighter, more detailed views and images.

Field of View (FOV)

In simple terms, your field of view is the amount of sky that is witnessed by your telescope/camera combination, or telescope/eyepiece combination. This measurement is calculated in angular degrees. To calculate how much of the sky you can image with your astrophotography rig, take the width of your camera chip, multiply it by 57.3, then divide that product by the focal length of your optics. If you want to determine how much of the sky you can view through your eyepiece, take the apparent field of view of your eyepiece (provided by the manufacturer), then divide it by the quotient of your telescope’s focal length & the focal length of your eyepiece.

Focal Length

The focal length is the distance, usually measured in millimeters, between the primary mirror or lens and the point at which the image comes to focus. Generally, classic refractors have a longer focal length, Newtonian reflectors tend to have a focal length that is shorter, and Schmidt-Cassegrain fall somewhere in the middle.

Focal Ratio

The focal ratio is calculated by dividing the aperture (mm) of the primary mirror or lens into the focal length. Example: 2500 mm divided by 254 mm (10") equals an f/ratio of 9.84, which is usually rounded off, in this case to f/10. The focal ratio signifies how quickly a telescope gathers light and tells us something about the telescope's field of view, how long exposures will take during astrophotography sessions, and how much magnification the eyepiece will produce for that telescope.

Focal Reducer

A focal reducer is an optical modifier that reduces the focal length of your telescope. These accessories come in a wide variety of reducing powers, and are typically dedicated for use with one specific telescope model. They are great options for those looking to widen their field of view without having to create complicated mosaics. Also, the use of a focal reducer increases the overall speed of the telescope, allowing more light to be collected in less time.

Image Circle

This specification refers to the area where an image is formed by the optics/ corrective element. This is useful for assessing whether a certain camera sensor size will be supported by the optics, or if vignetting/ poor performance will be seen in frame.

Imaging Newtonian

An Imaging Newtonian is a Newtonian telescope that has been optimized for astrophotography equipment. Where a traditional Newtonian would have its point of focus just above the end of the draw tube (in order to best focus with eyepieces), an imaging Newtonian is designed to focus further back to provide adequate space for astrophotography cameras and accessories. A side-effect of this focal point shift is a decrease in field-illumination, which presents as vignetting in images. Accordingly, imaging Newtonians also have larger secondary mirrors than their traditionally designed counterparts, which evens out illumination. In addition to these optical changes, these scopes can (but don't always) have hardware that has been upgraded or replaced with components that make attaching supporting equipment easier. Some of these scopes can be used visually as well as for astrophotography, however the optical changes and astrophotography hardware focused design does not make them the best candidate for visual observation.

Imaging Train

Your imaging train is your telescope, camera, and any other accessories that are fixed between them, such as filters, filter wheels, off-axis guiders, focal reducers, etc.

Optical Tube Assembly (OTA)

The acronym OTA stands for Optical Tube Assembly. An OTA is simply the telescope portion of a telescope/mount/tripod package. Some telescope users prefer to buy the OTA separately so they can create a custom astrophotography set-up or use a mount they already own.

Petzval Design

The Petzval design is an orientation of lens elements within a refractor telescope. This arrangement features a doublet near the front of the optical tube, and a doublet near the back of the tube, with air-spacing in between. The second doublet corrects for aberrations that the first was unable to correct for, such as comatic aberration and field curvature. As a result, refractors of this design are well suited for astrophotography, producing exceptional clarity and contrast within the images captured.

Quadruplet Refractor

Quadruplet refractors contain a total of four internal optical elements that provide images free from chromatic, comatic, and spherical aberration. As opposed to triplet refractors, quadruplet refractors also correct for field curvature aberration, where the additional lens acts as a built-in field flattener to straighten out incoming rays of light. This flat field also means there is no need to calculate backspacing; as long as the imaging system can reach focus, stars will be sharp across the entirety of the image. The four lenses in these telescopes can be arranged in various different orientations, though most often adopts the Petzval design. This design features two lenses in the front and two in the rear, and is so often used that quadruplets are regularly referred to as Petzval refractors. Most of the quadruplets produced today are manufactured specifically for astrophotography, and do not allow visual applications.

Quintuplet Refractor

Quintuplet refractors are telescopes that include a total of five lens elements. These lenses can be combined in various different arrangements to deliver superb color correcting abilities. Common aberrations such as chromatic, comatic, spherical, and field curvature are eliminated when using telescopes of this design, making them optimal for astrophotography. The inherent flat field also eradicates the need to calculate backspacing, making them exceptionally easy to use.

Rack & Pinion Focuser

Rack & Pinion focusers utilize a gear-oriented system to bring the telescope into focus. When the focusing knob is turned, the gears of the Pinion mechanism mesh with those of the Rack mechanism to move the eyepiece or imaging equipment into the focal point of the optics. By using gears, this type of focusing design is less likely to suffer from slippage as other focusers are prone to, and are one of the most commonly used in today’s most popular telescopes.

Reflector Telescope / Reflecting Telescope

A reflector is a telescope design in which mirrors are used to gather and focus light. Reflector telescopes are commonly called Newtonian Reflectors, or simply a Newtonian in deference to their inventor, Sir Isaac Newton.

Refractor / Refracting Telescope

A refractor is a telescope design that uses lenses to gather and focus light. While there are some exceptions to the rule, achromatic refractors use two lenses in their design, and while they are economical, achromats are only capable of focusing two out of three wavelengths of light. An APO telescope, or apochromatic refractor, uses 3 lenses to bring all three wavelengths of light to a single focus to produce an image virtually free of extraneous color.

Schmidt-Cassegrain Telescope (SCT)

The acronym SCT stands for Schmidt-Cassegrain Telescope, one of the most popular telescope designs in amateur astronomy today. A Schmidt-Cassegrain, which belongs more broadly to the Catadioptric telescope type, uses a folded optical design incorporating both mirrors and lenses to gather and bring the light to focus. The folded light path allows for a short tube assembly even with relatively large apertures of 8" or more. A shorter tube length makes the SCT far more portable than a classic Newtonian or refractor of the same aperture.

Spacer

These are fairly simple components, designed to add spacing to an imaging system. While there are some sizes that have become common due to corrective element backspacing, dedicated astronomy camera native backfocus, and popular accessory thicknesses coalescing around certain spacing distances, there are still plenty of unique sizes and thickness available for unique builds/ equipment.

Spherical Aberration

As opposed to converging at a singular focal point, light rays entering the edges of a lens focus at differing points than that of light rays entering the center of the lens. This results in sharp stars in the center of the frame while blurry, unfocused stars are prevalent around the edges of the image.

Vignetting

Vignetting is seen as the darkening of the corners of the frame within an image. This happens when the camera sensor is not exposed to enough light, resulting in a shadow effect along the borders of the image. This issue presents itself for a number of reasons, though most commonly occurs when using incompatible sensor sizes and image circles, and using too small of filters for the imaging assembly.