Top Astrophotography Accessories of 2024

Electronic Focusers

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Filter Drawers

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WiFi Camera Controllers

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Guide Scopes

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Imaging Filters

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Focal Reducers

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Portable Power Supplies

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Power Distribution

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Glossary

Astronomy

Astronomy is the scientific study of space and the celestial objects within it. It also deals with the physical universe as a whole. Astronomy can be broken up into four subcategories: astrophysics, astrometry, astrogeology, and astrobiology. The study of astronomy has helped measure time, seasons, and navigation on Earth.

Astrophotography

This refers to photography of astronomical bodies and phenomena. Astrophotography is not new, for example the popular T threading still used today harkens from Tamron’s T-mount developed for their 35 mm cameras - however it has seen a notable increase in popularity with improvements in cameras, mounts, filters, and software making astrophotography much more accessible. This is not limited to celestial bodies such as nebulae, planets, or galaxies either, as solar imaging is now more within the reach of the average consumer than ever before.

Auto-Focus

Automatic focusing utilizes software to shift the focus of a telescope in and out to determine the precise focal point of the optics. It does this by reading the star size at each focus point, creating a graph of this data, then finds the minimum star size; bringing the optics into sharp focus.

Autoguiding

Autoguiding is a process which utilizes a smaller telescope, referred to as a guide scope, and an additional camera sensor, known as a guide camera, to assist your mount in its tracking precision. Alternatively, this can be achieved using an Off-Axis Guider (OAG), which is fitted within your primary imaging train. An OAG uses the light captured by your telescope and sends it to your guide camera via an internal prism. So, how does autoguiding actually work? Your guide camera will take a constant series of short exposures (typically 1-3 seconds each) that will then be analyzed by software. After the software selects the best guide star(s) to guide upon, the goal is to keep these stars as steady as possible from frame to frame. If there is a discrepancy in the positioning of the stars, the guiding software will communicate with the mount to make small adjustments to fix these tracking errors. While it may not be necessary for short exposure astrophotography such as planetary, lunar, or solar, autoguiding is highly beneficial for long exposure astrophotography.

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.

Bahtinov Mask

A Bahtinov mask is a tool that aids the user in finding optimal focus and was created by Russian astrophotographer Pavel Bahtinov in 2005. This type of focusing aid creates 3 diffraction spikes over a bright star within the field of view. While adjusting the focus knob, the point in which the three lines intersect perfectly over the star result in perfect focus. This tool is widely used by astrophotographers worldwide and creates an effortless focusing routine.

Color Camera / One-Shot-Color Cameras (OSC)

Often referred to as One-Shot-Color (OSC) cameras, these cameras are able to produce an image in full color without the use of additional filters. This greatly simplifies the imaging process, and allows astrophotographers to complete a project in far less amount of time. They are especially useful for those who have limited clear nights, where they can go weeks to months without having an imaging opportunity due to their climate. These cameras are excellent choices to image the planets, the Sun, the Moon, and deep space.

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.

Dedicated Astronomy Camera

These cameras don’t look like what one traditionally thinks of when imaging a camera; instead taking the form of cylinders or pucks, with no physical controls, displays, or viewfinders to speak of. These require a computer or WiFi control device to take images, with more advanced models additionally requiring external power. What they give in return for all of these concessions is granular control over the sensor settings, increased sensitivity to wavelengths that more traditional cameras filter out, options for deBayered sensors (true monochrome), designs that easily connect with astronomy equipment, and in some cases cooling for increased performance.

DSLR / Mirrorless Camera

What one may consider a “regular” camera; used for everyday photography and feature an interchangeable (removable) lens system. Popular brands from this category that also enjoy wide support in the astrophotography hobby are Sony, Canon, and Nikon.

Finder Scope

A finder scope fits on top of the main telescope and is used to help you find and center objects in your eyepiece. A finder can be as simple as a red dot finder or it can be a high quality small telescope in its own right.

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.

GPS

Originally invented by the U.S. Department of Defense, this technology became fully functional in the United States in 1995. This radio navigation system utilizes satellites to provide the precise global position of GPS enabled devices. Out of the 31 GPS satellites orbiting Earth today, GPS receivers only need information from 4 GPS satellites to determine accurate location. Cell phones, computers, and endless other devices act as GPS receivers. GPS is helpful in astronomy and astrophotography by providing the imaging software with the correct time, date, and location, helping create a detailed image of what the sky should look like based on this information.

Guide Camera

A guide camera has the important job of assisting your mount with its tracking capabilities. It does this by capturing constant frames of the night sky, usually 1-3 seconds each, that are then sent to autoguiding software. The software analyzes the field of view, selects guide stars and determines their center of mass, then compares each incoming frame to this calculated center of mass. If any discrepancies are found between the captured frames, the software will then communicate with the mount to fix these errors.

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.

Light Pollution

Light pollution is the brightening of the atmosphere due to lights from streetlamps, other forms of artificial light, and even the Moon. As light enters the atmosphere, it washes out the night sky, making it very difficult to observe the stars, nebulae, and planets. In order to combat light pollution in astrophotography, special filters have been developed to cut through excess light and enhance images. These filters are known as City Light Suppression filters, commonly referred to as CLS filters.

Monochrome Camera

Monochrome cameras deliver the most detail and sensitivity out of all other camera options. Color cameras have an arrangement of pixel filters in a 2x2 grid, typically consisting of two green, one red, and one blue, which is then repeated across the entire sensor in what is known as a Bayer pattern. Monochrome cameras however, have photosites that do not contain an alternating pattern of those red, green, and blue light pre-filters. Instead, their photosites collect all incoming light regardless of color – allowing for up to 3x the collection of signal (red, green, and blue light). Because the camera itself is not pre-filtering each color, in order to produce a full color image, they must be paired with filters to create a full color image. These filters can range from simple RGB filters to narrowband filters, and the collected data is then combined in a photo editing software. Though light is still passed through an external filter, every pixel well is utilized, resulting in 4x more red or blue signal and 2x more green signal compared to a color camera.

Nebula

A nebula is a type of celestial body that is made up of gas and/or dust. There are 3 different types of nebulae within space. Emission nebulae have a “glowing” effect, where they absorb and emit light from surrounding stars. The colors emitted are entirely dependent on the gasses present within the nebulae itself. This type of nebula also includes planetary nebula and supernova remnants, produced by stars themselves. As opposed to emitting light itself, reflection nebulae reflect starlight from neighboring stars. Reflection nebulae are typically blue in color, such as the Pleiades or the Running Man Nebula. The last type of nebulae is dark nebulae, which blocks stars and other objects from our view, creating a dark silhouette.

Nosepiece

An adapter that allows cameras to be installed in place of visual observing equipment such as diagonals or eyepieces. These adapters feature threading for a T-Ring or camera on one side, and an 1.25” or 2” barrel on the other.

Off-axis Guider (OAG)

As opposed to using a guide scope, off-axis guiders are fitted into the main imaging train itself, and utilizes the incoming light from the primary telescope for guiding. It achieves this via an internal prism that sends light into the guide camera. When using traditional guide scopes, these scopes can alter in position slightly through the night of imaging, causing the issue of differential flexure. But utilizing the main imaging rig’s incoming light, off-axis guiders eliminate this issue.

Plate Solving

The process of plate solving involves software analyzing a captured frame and comparing the star patterns to a database to determine the exact pointing position of the telescope. This procedure is incredibly helpful in Go-To processes, allowing the user to slew directly to the desired object with the click of a button.

Polar Alignment

Polar alignment is the process of aligning a telescope mount’s polar axis with the Earth’s axis of rotation. By having these two axes parallel to one another, precise counteraction of the Earth’s rotation can then be achieved. While a typical process of equatorial mounts that have three inherent axes of rotation, a similar effect can also be achieved by utilizing an equatorial wedge with two-axis alt-azimuth mounts.

Post-Processing

In order to complete an astroimage, it’s necessary to bring the captured frames into software to perform post process editing. This action varies for different types of astrophotography, though in general, it involves image stacking to reduce noise and remove artifacts, and image editing to enhance the captured detail and color.

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 telescope is an optical instrument that utilizes refraction of light to create a visual image. This telescope type uses an objective lens to bend/refract light from far away objects to magnify them, as well as allowing them to appear brighter and clearer. Refractors were created in 1608, and their creation is attributed to Hans Lippershey, a Dutch lens maker.

Sky Atlas

Sky Atlas is a digital planetarium created by ZWO for their ASIAIR and Seestar platforms. Digital planetariums are representations of the night sky as it appears at a certain time and location, generally synchronized to those of the user. This allows users to look for objects to observe/ image, usually showing a visual representation and technical information about the targets. In more advanced planetariums like the Sky Atlas and those included in most other smart telescope apps, GoTo functionality will be included to slew the user's telescope to whichever section of the sky they desire.

Software

Software consists of programs and date used by a computer to complete certain tasks.

T-Adapter

Typically this is used to describe an accessory for SCT telescopes, which is threaded to the back of the OTA or reducer (replacing the visual back). These spacers add enough space to the imaging train such that only the industry standard 55 mm of backspacing remains. For information on the adapter that connects directly to a DSLR/ mirrorless camera, see T-Ring.

T-Ring

A T-Ring is an accessory that is used to connect a DSLR/ mirrorless camera to threaded connections. These have a camera lens mount on one side, and a female/ internally threaded connection on the other in either M48 or M42. Most (but not all) T-Rings will set the camera at 55 mm of backspacing, making connections easy.

Tracking

As the Earth is continuously spinning and in motion, the location of a celestial object in the sky moves over the course of a night. This becomes apparent during observation as a target moves out of view, and particularly observable in images as stars and objects quickly become a blur as exposure time and focal length increases. To compensate for this, computerized mounts and smart telescopes employ tracking techniques to keep the target centered in the optics. Depending on the motion style of the mount, the resulting image can vary. Alt-Az motion, popular in smart telescopes, keeps the object centered but can not compensate for its “spin” without what is known as a wedge. Accordingly these images lose information on the edges of the frame as they rotate out of view, leading to ever smaller, circular, images as time spent imaging increases.

USB

Universal Serial Bus or USB is a protocol for data transmission, and is by far and away the most common way astronomy equipment will communicate with a PC in a wired capacity. There are a number of USB connectors, such as USB-A (the rectangular port you’re likely familiar with), USB-B, USB-C, and micro USB; as well as a number of different revisions (2.0, 3.0, 3.1, etc.) that have brought more speed, power, and reliability to the protocol.

WiFi (Wi-Fi)

Wi-Fi, sometimes shortened to just WiFi or wifi, is a protocol for wireless communication. Primarily it is used to transmit and receive data between a device (such as a smartphone, computer, smart TV, and an ever increasing number of other household devices) and a router or wireless access point that is connected to the internet. Communication with the internet is not the only function the Wi-Fi protocol is useful for, and indeed many of the aforementioned devices can communicate with each other locally using this protocol and the router as an intermediary. Increasingly this protocol has been used for more direct communication between two devices (like a smartphone and a smart telescope), with one creating its own access point or broadcast that both devices then send and receive data on. While this does have the disadvantage of disconnecting a device’s connection to the internet, it has become necessary to transfer large amounts of data quickly that otherwise exceed what Bluetooth can accommodate.