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Choosing a mount for Astrophotography

No matter how excellent your optical and imaging equipment setup may be, you won’t be able to get great results if you can’t keep them locked on target! That is why it is important to not just get a mount, but to get one that is matched with your gear — and your use case. As the astronomy community has grown, so too have the options available to modern day astrophotographers, providing options that not just are suited for a given payload requirement but also where you intend to image from and what ‘quality of life’ features you’re looking for. This is a bit of a double-edged sword however, as it can make it hard to decide which mount is the right one for you!

Well fret not, as our Gear Experts have taken the guesswork out of selecting an astrophotography mount! In our Telescope Mount Buying Guide we’ve created a five-point approach to assessing the needs of your system and determine whether you need a Portable Grab and Go, Backyard Observing, Remote Observatory Grade, or New Wave Harmonic class mount. Once you have a good idea of what type of mount you need, click the corresponding badge below to see our curated selection of gear suited for your imaging needs.



Portable Grab and Go
Backyard Observing
Remote Observatory Grade
An image showing both an Annular and Total solar eclipse New Wave


Traditional Geared EQ

While the exact way motorized mounts have traditionally driven their axis varies, with some using belts, worm gears, combinations of these, or other similar mechanical gear transmissions, in practice they all function in much the same way! The key differentiating feature between these mounts and newer harmonic drive designs is: balance. Traditionally geared equatorial mounts require that you counterbalance the strain your equipment puts on the motor drive system. Failing to properly counterbalance your gear with these mounts can result in sub-optimal performance, or even damage to the gearing if the mount is grossly imbalanced (or not counterbalanced at all). However, while finding the ‘perfect’ balance can at times be elusive, balancing these mounts such that you can prevent damage and experience good performance is very simple!

A Celestron AVX Mount

As these types of EQ mounts have been the standard for quite awhile, the options available in this category are vast. You can find models for most any payload, budget, and use case, as feature rich or utilitarian as you need — and while you can’t always find something that checks all of these boxes at the same time, we’re confident that most everyone can find a something well suited to their situation in this mount category.

While this style of mount may not be on the ‘bleeding edge’ (though, we’d argue that there are certainly some mounts of this design that continue to push boundaries), this can be a positive thing — as the maturity of this technology means that major kinks have long since been ironed out, and compatibility, accessories, as well as support is more readily available. For example, while the Celestron Advanced VX Equatorial Mount and Sky-Watcher EQ6-R Pro Computerized Equatorial Mount are not the newest offerings on the market, they have remained popular, solid, and reliable options for years.

Advantages of Geared EQ

  • Tried-and-True design means greater software/ gear compatibility, OEM and aftermarket upgrades are more available, larger knowledge base to draw from for support, and the reliability that comes with these time-tested designs.
  • Many models available, providing a better chance that users can find a mount or mounts that exactly fit their needs/goals.


Disadvantages of Geared EQ

  • Requires balancing with counterweights in all cases, increasing the weight of the setup overall and the time it takes to set up.
  • While some models do push the envelope, it is not uncommon to see technology and hardware that matches the maturity of these gearing designs.

Harmonic mounts

Harmonic/strainwave drive mounts, like the popular ZWO AM5 Harmonic Drive Equatorial Mount and Sky-Watcher Wave 150i Strainwave Mount Head, are a more recent design in the amateur astronomy community, and set themselves apart with their ability to ‘thrive under pressure’, as these mounts can function without a counterweight in place! This ability comes from the use of a strain wave gear or gears, which give the motor a large amount of mechanical advantage in a relatively small space — much, much more than what is seen with more traditional gearbox designs. Without the need for counterweight, these mounts are both easier to set up and easier to transport, but there’s a lot more than just weight/time savings with these new designs!

A ZWO AM5 mount

Along with a fresh take on the gear system has come a shift towards more modern features, control interfaces, and design language. While strain wave mounts are by no means the first or only mounts to implement things such as — app/PC control as the default method of interaction instead of a hand controller, lightweight housings made of CNC steel or aluminum, 12V and/or USB passthrough slots built into the default saddle or available as an upgrade, carbon fiber tripods being the standard vs the steel units packed in with traditionally gear mounts — all or most of these more modern ‘quality of life’ features are things you will find included in this class of mount.

While the no-counterweight-required nature is the big draw of these mounts, you may note that most still allow you to add a counterweight shaft and counterweight. Why? Well when installed you can push the performance of these mounts even further — increasing the max payload for some truly impressive weight capacity to unit weight figures.

With all these benefits, you may be wondering why you would want to consider a conventional EQ mount. While these new wave mounts are certainly an exciting development in the amateur mount space, and something to keep an eye on, this is very much a newer technology at the moment. Accordingly the knowledge base and support for these mounts, in both the third party software and troubleshooting/technical sense, is behind the large wealth of knowledge, experience, and support that is available for conventional EQ mount models (though with the popularity of some of these strain wave mounts, this is growing quickly). Additionally, while many manufacturers are exploring this new mount technology, the variety of models available is notably smaller than that of conventionally geared mounts.

Harmonic mounts Benefits

  • No counterweight required.
  • Excellent payload capacity to mount weight ratio.
  • Modern and advanced features being included or available is the norm.


Disadvantages of Harmonic mounts

  • Fewer model/options available compared to conventionally geared EQ mounts.
  • Newer technology, meaning knowledge base is still developing.

Star trackers

A star tracker is a popular type of EQ mount that is designed for very light imaging equipment, such as DSLR/mirrorless cameras and photography lenses or short focal length lightweight telescopes. Besides having a payload below even what we consider a Portable Grab & Go class mount, star trackers like the Sky-Watcher Star Adventurer 2i and iOptron SkyGuider Pro Camera Mount have traditionally motorized the RA axis only, leaving the DEC axis static during image capture. While this may sound like it would lead to a blurry mess, with the exposure times and focal lengths common to photography cameras and lenses this is actually not the case — as the majority of motion occurs around the RA axis!



Sky-Watcher GTi mount

Newer star trackers, like the Sky-Watcher GTi, have begun to add motorized DECs. This is perfect for users looking to build an imaging rig that pushes the boundaries of what an ultra-portable setup can do, allowing you to use slightly longer focal lengths and longer exposure times than what an RA tracking only mount can provide.

With their primarily DSLR/mirrorless camera focused design these mounts are more than just great ultra-portable mounts, but also an excellent entry point into the astrophotography hobby. Though the controls and features are usually basic (particularly on the RA tracking only models), for beginners and/or for those looking for a simple wide field setup this can be a good thing! The low payload and usual lack of DEC tracking do mean these are not able to support the ‘next steps’ most take into astrophotography, however the ease of use combined with the more accessible price still make them a good foundation to build from.

Star trackers Benefits

  • Affordable entry point to a tracking mount for wide-field astrophotography.
  • Very portable.
  • Newer models with DEC tracking and more features make for great high performance, ultra-portable, wider-field imaging builds
  • Basic feature set makes learning to use and master the mount easy.


Disadvantages of Star trackers

  • Low payload capacity and typical lack of DEC tracking limit this to mostly just DSLR/mirrorless cameras or ultra-portable wide field telescopes with lightweight imaging trains.
  • Payload limit, common RA-only tracking design, and basic feature set mean that these typically don’t support the gear users pick up when taking their ‘next steps’ into the hobby.

Dual EQ/AltAZ

Dual EQ/AltAz mounts are a special class of mount that combine an EQ mount and an AltAz mount into one convertible package! These mounts can counter the Earth’s rotation when you want to image, or provide an easy-going setup and use experience when you’re looking to observe. While these classically have been a bit of a niche offering, the entry of harmonic gearing into the amateur astronomy space has reinvigorated this dual mount category!



The Sky-Watcher AZ-EQ5 mount

While EQ mounts can absolutely be used for visual observing, there is something to be said for the simplicity of setting up and using an Alt/Az mount — and for those looking for a mount that can be used for daytime observing there is no contest. These dual mounts provide both forms of movement by designing an RA housing that can be pointed straight up-and-down, thus transforming it into an Azimuth axis and the DEC axis into Altitude. This is similar in concept to how a wedge converts an Alt/Az mount to an EQ mount, however dual EQ/AltAz mounts like the Sky-Watcher AZ-EQ5 Multi-Purpose GoTo Mount have traditionally had the advantage of higher payload capacity thanks to their ability to counter-balance.

Classically this category of mount has had a fairly limited number of options, however thanks to strainwave technology this is no longer the case! iOptron and Sky-Watcher have begun to offer models like the Sky-Watcher Wave 100i Strainwave mount which leverage the compact nature of strainwave mount design to add Alt/Az functionality to these excellent EQ mounts!

Dual EQ/AltAZ mounts Benefits

  • Provide the flexibility to counteract rotation when imaging, and a simplified setup/user experience when using the mount visually.


Disadvantages of Dual EQ/AltAZ mounts

  • Classically a niche category meaning options have been limited with conventionally geared mounts, though this has been changing with the growing popularity of strainwave mounts.
  • Conventionally geared options are more expensive and complicated than their EQ-only equivalents.

Polar Alignment

You may have heard that the need for ‘polar alignment’ is a key difference between EQ and Alt/Az mounts, but what exactly is a polar alignment, why is it important, and — perhaps the most common and important question of all — how do you polar align a mount?



An iOptron iPolar

EQ mounts ‘freeze’ celestial objects in place by counteracting the rotation of the Earth. This is achieved by rotating around the same ‘center-point’ as the objects in our night sky appear to rotate around, which are marked by Earth’s celestial poles. How close an EQ mount’s center of rotation is lined up with this celestial pole or ‘center-point’ is what we’re referring to with the phrase ‘polar alignment’, and with the process of lining the two up, ‘polar aligning’.

Achieving a good polar alignment is key to freezing celestial objects in place for the long exposure times used in astrophotography. How close the alignment needs to be does depend on the focal length of a setup, with wider field imaging rigs being a bit more forgiving of misalignment, but you should aim to be as precise as possible!

How exactly does one polar align an EQ mount? Well, there isn’t one set way, but rather a number of different methods you can employ depending on what gear you have and what your needs are!

  • Using a polar scope: These are installed inside, or close to, the center of rotation for the RA axis. You then look through the polar scope and line up etchings in the glass with constellations, or place a star at a specific point. The latter is becoming more common, using Polaris (in the Northern Hemisphere) and a circular etching, where either the hand controller or an app will note where on the circle Polaris should be placed.
  • Using an electronic polar scope: These tools are small cameras that are placed where a traditional polar scope would be installed, often times replacing it. These cameras work in conjunction with dedicated software which takes an image of the sky, calculates how this differs from the 'ideal' polar alignment, and guides the user until the image through the electronic polar scope matches what it should be for your date, time, and location. Popular options for this method are the QHY PoleMaster and the iOptron iPolar.
  • Using plate solving and software: This works similarly to an electronic polar scope, in that plate solving is used, however this approach is used with a camera and scope that is not at the center of rotation — i.e. with your imaging camera and telescope. To account for this, these software approaches require information about the camera sensor size, telescope focal length (which can usually both be gathered without user input) as well as requiring the equipment rotate a certain amount (which the program can sometimes also do). After this is done, then the process proceeds in much the same way as an electronic polar scope, with on-screen feedback that guides the user through adustments.

For more information on polar alignment, be sure to read our article on Polar Alignment!

Star Alignment

One star, two star, three star alignment — these star alignment procedures are used to refine your GoTo model after achieving polar alignment. While less critical for freezing the sky in place for imaging, this is still a crucial step in the astrophotography process. No matter how well you can lock your mount’s tracking on a section of the night sky, all that effort is moot if the object you’re trying to image isn’t there!



Celestron StarSense Auto Align accessory

The GoTo technologies built into today’s mounts can’t ‘see’ the night sky, and are entirely reliant on the information provided to them, assumptions about how the mount is set up, and the models built into them. While we may aim to be as precise as possible when leveling, entering the date/time/location, and polar aligning, the reality is that things will not be exact. When things deviate from ‘exact’, GoTo’s will be impacted. With visual use this can be frustrating, but for objects bright enough to be observed through an eyepiece, usually you can compensate by manually slewing to center the object (so long as the GoTo isn’t too far off). With the deep sky astrophotography however it can be hard to judge and tedious to adjust framing, as these targets often require several minutes of exposure time before you can see how close to centered your GoTo got.

Star aligning corrects for the small errors that cause these missed GoTos by syncing up the calculated internal sky model with a series of reference points — the one, two, three, etc. stars selected during a star alignment procedure. By manually centering a selected star, you’re essentially snapping the internal model’s star to this point. The more reference points you use, the more accurate your GoTo will be!

Newer software tools like those found in the ZWO ASIAIR are making this process less critical, with plate solving. When connected to your imaging camera and mount, these tools can assess where the mount is actually pointed vs. where it was asked to point, and send corrections accordingly. Additionally Celestron offers the StarSense Auto Telescope Alignment Accessory, which uses a camera and a special hand controller to automate this process for Celestron NexStar mounts. However even with the advent of these features star alignment is still a useful tool to help cut down on the amount of time spent correcting your mount’s pointing!

Celestron additionally has an All-Star align process that is similar to the star alignment process — however instead of being use to adjust your mount's internal GoTo model, this instead helps adjust polar alignment. After star aligning your Celestron mount, this slews your mount to the position where a star would be if the mount was polar aligned. You then simply adjust the mount's polar alignment points until the star is actually centered, allowing the mount to polar aligned even when you do not have a clear view of Polaris!

Connecting your mount to a computer

Connecting your mount to your computer comes with a whole host of benefits — connectivity with more accessible control interfaces, autoguiding integration, and access to plate-solve-and-resync features to correct GoTo errors. With systems like the ZWO ASIAIR Plus WiFi Camera Controller and StellarMate X/Pro Astrophotography Controllers, connecting your mount is typically as easy as linking the two with a USB cable (like the Apertura Braided USB 2.0 Cable) and selecting your model from a list. Laptops and miniPCs on the other hand are a bit of a different story!

The Apertura Braided USB B Cable for Sky-Watcher EQ6-R Pro mounts

As these systems are not tailored specifically towards astronomy like the offerings from ZWO or StellarMate, they do not come with the tools your PC needs to ‘talk’ to your gear preinstalled — and just like a lot of other 3rd party devices you’re likely familiar with, this means you’ll need to install a few drivers and programs!

The process will vary depending on what brand of mount that you have (and be sure to check out our Astronomy Hub to see if we have specific guides for your mount, like the Sky-Watcher EQ6-R Pro Computerized Equatorial Mount!), but generally the process is as follows:

  • Navigate to the manufacturer’s website and check their downloads page for the mount control programs, any native drivers that might be available, as well as any ASCOM drivers. If you do not have the ASCOM program installed already, you’ll want to download this as well.
  • After installing the software, connect the mount to your PC via a USB connection on the hand controller, and then turn the mount on.
  • Launch the manufacturer’s control program, and follow the directions for connecting to your mount.
  • You’re now ready to control the mount from your PC! If you want to connect your mount to other programs, this is where ASCOM comes in; however you may also need to leave the manufacturer’s control program running as well.

Guiding

No system is perfect! Regardless of how precisely you polar align or the quality of your mount, the reality is that your mount will need a bit of help to keep it on target for long exposures and/or with long focal lengths. Just as star alignment can help correct for these errors for GoTo, we have a process to correct for errors when tracking called ‘guiding’ or ‘auto-guiding’.

Guiding window

Guiding used to be a manual process, but thankfully technology has automated this! Currently the most popular way to auto-guide is with a guide camera, a guidescope or OAG, and with a program (the most popular of which is by far PHD2). This setup watches a star/set of stars for movement, and should these drift a command is sent to move the mount in the opposite direction. This will effectively counteract any drift occurring due to imperfect polar alignment or imperfect tracking, keeping the mount more or less locked on to the celestial target for the duration of the imaging session!

This process comes with its own set of considerations and setup, like sorting out how to add an OAG to your imaging train (and spacing for your guide camera), mounting/pointing/focusing a guidescope. It also isn’t a ‘magic bullet’ that will fix all of your tracking woes — even when set up correctly, there will still be some error (measured in arcseconds RMS). Additionally, while it might be possible for the guiding program to bring your mount back on target after a large deviation, you’ll get better results if the corrections needed are small. In other words, while guiding is an excellent tool for pushing your exposure times, it is not a replacement for polar alignment! For more information on guiding, be sure to check out our article on autoguiding.

Mount FAQ: What You Need to Know

Your astronomy mount are the shoulders that all your other gear rests upon, and so choosing the right mount for your needs and goals can be just as important a decision as what telescope or camera you should purchase. But why should you be looking at an EQ mount instead of an Alt/Az option? Do you need to purchase a guiding setup? We’ve compiled the answers to these common questions and more below, so read on for more info on what the right astronomy gear platform for you is!

What is the best mount for astrophotography?

There are plenty of premium options, like the Software Bisque Paramount series, that could perhaps compete for the spot as the best mount for astrophotography — but with the wide range of goals, needs, and budgets, a better question is perhaps what is the best astrophotography mount for your needs? A heavy-duty mount that can shoulder 120 lbs. of equipment might be the best mount for a remote observatory, but would be a terrible mount for a portable grab and go imaging rig. In our Telescope Mount Buying Guide we take a look at this subject further, and give you the tools you need to help find the best astrophotography mount for you!

Why is an EQ Mount Recommended for Astrophotography? Can I Use an Alt/Az?

Due to Earth’s rotation celestial objects don’t just move across the night sky, they change their orientation as well. This is a twofold problem for astrophotography. Firstly, if we merely keep the object in the center without counteracting Earth’s rotation, then the corners of our image will rotate out of frame, resulting in a final image that either has lower signal on the edges or a crop that discards those sections. As the object is rotating in the center, this also means that our exposure times need to be relatively short to ‘freeze’ the motion, meaning less signal per frame — a detriment when trying to capture fine detail in faint deep sky objects. This is why it is critical to have a platform that doesn’t just keep objects centered (Alt/Az mounts), but that can keep objects centered by spinning with them and therefore allowing for long exposures that maximizes signal across the entire framing (EQ mounts).

What about using an Alt/Az mount and a wedge?

You may have heard of Alt/Az wedges, an accessory that allows you to ‘tip’ an Alt/Az mount upwards, allowing you to counteract Earth’s rotation like an EQ mount. It is true that you can push exposure times and maintain your framing with a wedged system, however we typically do not recommend this setup if astrophotography is your goal. EQ mounts are designed specifically to counteract Earth’s rotation, and this native support makes them easier to set up and use. Technical arguments, such as whether the argument that EQ mounts track better than wedged Alt/Az mounts, and ease of use arguments aside, it is inarguable that in the amateur astronomy space EQ mounts have more models, features, and community support, dedicated to astrophotography, thus making them a much better choice for those looking to enter the world of deep space imaging.

Can I do Astrophotography with an Alt/Az Mount?

There are types of astrophotography that are less sensitive to the field rotation present in an Alt/Az mount — Lunar, Solar, and planetary! A way to take (or with planetary, the way) these types of images is by taking a lot of very short exposures (usually by simply capturing a video), so short that rotation of the object in question is a non-issue.

Can I manually control a computerized/GoTo mount?

Absolutely! Traditionally these mounts have included a hand controller that allows you to not only select the GoTo targets and adjust the mount’s settings, but also manually command the mount to move. Manufacturers have begun to explore wireless control methods, which allow the user to control the mount from a mobile device — and we’re happy to report that manual controls are present here too.

Can astrophotography be done without autoguiding?

While guiding is a big help, especially with fainter deep sky objects and longer focal lengths, it is not required to take an astrophoto! Be as precise as possible with your polar alignment, conservative with your exposure times, and take as many images as you can and you can create some great images.

Do I Need an Astronomy Mount or Star Tracker to Image Deep Space Objects?

Technically speaking, it is possible to take wide-field astrophotos of bright objects without a dedicated star tracker or astronomy mount. However it is a limited and intensive process that we find does not provide the results that most have in mind, and accordingly strongly recommend a tracking mount of some kind.

What is a ‘GoTo’ mount?

‘GoTo’ technology is an excellent addition to motorized mounts that allows you to easily locate interesting celestial objects in the night sky! With just your date, time, and location information, GoTo mounts can build a virtual model of the sky around you. This allows them to then ‘know’ where to point your telescope to view any set of given astronomical coordinates — whether that be coordinates from the named object list, or a set of coordinates that you provide!

Mount Terms To Know

All-Star Polar alignment

All-Star polar alignment is an innovation from Celestron that allows you to polar align your mount with the Celestron NexStar hand controller. As opposed to other polar alignment methods, this approach does not require a clear view of the north or south celestial pole, allowing you to set up almost anywhere even in the presence of large obstructions. The process is simple: once you have successfully star aligned your mount, slew to a bright star from the hand controller’s database. Next, press the Align button on the hand controller, then “Polar Align”, then “Align Mount”. Your mount will then re-slew to this star, and prompt you to center it within the eyepiece or camera. Next, the mount will position this star in the exact location it should be if your mount was properly polar aligned. Finally, adjust the altitude and azimuth knobs in your mount to re-center this star, and press enter. Your telescope mount is now accurately aligned with Earth’s axis of rotation!

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.

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.

Equatorial Mount

An equatorial mount is an astronomy instrument that features two axes of rotation: right ascension (RA) and declination (DEC). These two axes of rotation are also found on alt-azimuth mounts, though equatorial mounts feature an additional axis, called the polar axis, that the RA and DEC axes rotate about. This polar axis is to be lined up with Earth’s celestial pole to accurately counteract Earth’s rotation. These mounts are ideal for astrophotography applications, as the addition of a polar axis eliminates the issue of field rotation within captured images.

German Equatorial Mount

A German equatorial mount is a specific type of equatorial mount created by Joseph von Fraunhofer in 1824. These mounts feature a design that places the telescope on one side of the declination axis, which is offset by counterweight(s) on the opposite end. The declination and right ascension axes meet each other within a T-joint. This T-joint is aimed at the north or south celestial pole, parallel to Earth’s axis of rotation, and rotates about this polar axis. With these three axes, these mounts are popular within the astrophotography community due to their ability to counteract Earth’s rotation without presenting field rotation within the captured images.

GoTo (Go-To) Technology

In simple terms, Go-To technology is a telescope mount’s ability to slew to an object in space. This process requires alignment with the night sky, and is achieved through correlation with the optics of the telescope and software. Alignment can be achieved a number of ways and is necessary in order to determine the pointing position of the telescope. The user can either calibrate their telescope with 1-3 well-known bright stars or planets, or can utilize plate solving if their software offers it. In plate solving, the field of view is compared to a database, and the software can then determine the exact positioning of the telescope. Plate solving is considered more accurate than star alignment, and is widely featured within the smart telescopes on the market today for accurate Go-To functionality.

Harmonic EQ

Harmonic equatorial mounts, often times referred to as strainwave mounts, are a type of equatorial mount with unique internal gearing. How these mounts work is as follows: A motor within this mount attaches to an internal wave generator, which is fixed inside of a flexible spline gear. While the motor rotates this wave generator, the flexible spline gear then pushes against the ring gear it’s housed inside of. The coupling of the flexible spline gear and ring gear is what drives the mount. One key advantage of this internal gearing system is that it can work with unbalanced loads, making the use of counterweights optional in most cases. Also, these mounts deliver high torque values, and have impressive weight-to-payload ratios. As such, these mounts are much smaller and more compact than other equatorial mounts, making them ideal for traveling.

Meridian Flip

While tracking the night sky, there may be a time when your target reaches the meridian, the imaginary line directly overhead that can be traced from the north celestial pole to the south celestial pole. While your telescope is pointed this high in the sky, it’s necessary to “flip” your equipment to the east side of the tripod or pier, so you can continue to track your target and avoid a tripod collision.

Polaris

Polaris is the pole star for the northern hemisphere, and is often referred to as the North Star. It resides >1 degree away from true celestial north, therefore appears to be fixed in one position night after night. It has a magnitude of 1.98, making it easily detectable to the naked eye in the night sky. Due to its brightness and stationary disposition, it has been used for centuries for navigation, helping sailors and other travelers on their voyages. This star is the brightest star within the Ursa Minor constellation, and is the last star within the “handle” of the Little Dipper asterism.

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 a polar axis, a similar effect can also be achieved by utilizing an equatorial wedge with alt-azimuth mounts.

Polar Scope

Polar scopes are small telescopes that assist with aligning a mount’s polar axis with the Earth’s axis of rotation. They are found within your mount, and are fitted with an internal reticle that shows Polaris’s position in reference to the true celestial North Pole, and Sigma Octantis’s position in reference to the true celestial South Pole. Through alignment of these pole stars within the polar scope, the mount will then be accurately polar aligned.

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.

Tracking Modes

As opposed to the tracking rate that determines the speed in which the mount will track the sky, the tracking mode of a telescope mount determines the way in which the mount will counteract the Earth’s rotation. This can be selected from either the hand controller or software. Typically, you will find the modes of: EQ North, EQ South, Off, and Alt-Azimuth. For instance, if you are polar aligned with the north celestial pole, choosing EQ North will be the appropriate tracking mode to select, while EQ South is reserved for those polar aligned with the south celestial pole. Equatorial tracking modes are optimal for astrophotography applications, while the alt-azimuth mode is ideal for those who are conducting visual astronomy.

Tracking Rates

Unlike the tracking mode which denotes the way in which the mount will track the sky, tracking rates determine the speed at which the mount will track the sky. This can be selected from the mount’s hand controller or through computer software, and should be selected based on the target that is being tracked. Typically, there are three tracking rates: Sidereal, Lunar, and Solar. The sidereal tracking rate moves the mount at a speed that is equivalent in magnitude, yet opposite in direction as the speed of Earth’s rotation. This is ideal for all targets within the night sky save the Moon and the Sun, in which the lunar and solar tracking rates are appropriate for.

Worm Gear

A worm gear is a component within a worm drive gearing system that includes spiral threads. Driven by a motor, this worm gear’s threads mesh with the worm wheel to then rotate the right ascension or declination axis of a mount.

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