Before diving into the details, let's clarify your goals and needs with a few questions to help identify the best telescope and accessories for you:

Have your answers ready? Let’s explore the essential equipment in four main categories:

> Telescope OTA

> Visual Observation Accessories

> Photography Equipment

> Mounting & Tracking Systems

Telescopes come in various optical systems, generally classified into the following categories:

• Refractor Telescope A classic and beginner-friendly choice, refractor telescopes feature a lens at one end for light entry and an eyepiece at the other for viewing. These telescopes are durable, simple to use, and require minimal maintenance, making them a popular choice for newcomers. While it’s a bit pricier than some options, it’s reliable even in low-light conditions, though it can sometimes show slight color distortions.

• Newtonian Reflector Designed with mirrors instead of lenses, Newtonian reflectors provide bright, clear images without color distortions. They are affordable and ideal for beginners seeking excellent brightness and image quality. However, they require regular alignment and cleaning due to their open-tube design, which makes them more susceptible to dust and moisture. Additionally, they can be somewhat heavy.

• Cassegrain Telescope Known for its unique design with a hole in the primary mirror, this type allows light to travel further within the optical tube, producing sharp, high-quality images. Compact and powerful, Cassegrain telescopes are ideal for those seeking longer focal lengths.

• Catadioptric Telescopes Blending the advantages of lenses and mirrors, catadioptric telescopes offer exceptional versatility. The Schmidt-Cassegrain is renowned for breathtaking sky views and astrophotography, while the Maksutov-Cassegrain excels at delivering sharp, detailed planetary views. Compact and versatile, these telescopes are ideal for enthusiasts, though they are often more expensive and may offer narrower fields of view.

At our core, we specialize in refractor telescopes, mainly offering four distinct lens system options: Doublet, Triplet, Petzval, and 7-element designs.

The Triplet is a versatile mid-range lens system, ideal for both visual observation with an eyepiece and astrophotography. For a more budget-friendly option, the Doublet system is perfect for beginners looking for quality within a lower budget.

The Petzval and 7-element lens systems offer even higher image quality and require no additional field flatteners, making them excellent for astrophotography. Among them, the 7-element Pleiades series provides the ultimate correction performance, crafted for professional photographers.

Once you've explored the different telescope types, you can choose the one that best aligns with your needs and budget. For details on specifications like aperture and focal length, refer to our guide - Telescope Specifications Explained - for an in-depth explanation.

An eyepiece is an essential accessory for visual observation, turning the focused light from the telescope into a viewable image. When selecting an eyepiece, it’s helpful to understand a few key specifications:

• Focal Length

The focal length of an eyepiece determines the magnification. With the same telescope, shorter focal length eyepieces deliver higher magnification. It is beneficial to have a range of eyepieces (short, medium, and long focal lengths) to achieve different magnifications for observing celestial objects of varying sizes.

$\text{Magnification}=\frac{\text{Telescope Focal Length}}{\text{Eyepiece Focal Length}}$

• Apparent Field of View (AFOV)

The AFOV, measured in degrees (°), represents the width of the sky you’ll see through the eyepiece. A larger AFOV gives you a more expansive, immersive view, which can be particularly enjoyable for wide-field observations. You can also calculate which focal lengths and AFOV are best suited for observing specific objects based on your telescope's focal length. (Refers to Apparent Size of Common Celestial Objects)

$\text{FOV}=\frac{\text{Apparent FOV}}{\text{Magnification}}=\frac{\text{Apparent FOV}\times\text{Eyepiece Focal Length}}{\text{Telescope Focal Length}}$

• Eye Relief

Eye relief is the optimal distance from the eyepiece to your eye for viewing a sharp image. Longer eye relief is especially helpful for users who wear glasses, as it allows a comfortable distance between the eye and eyepiece without losing the field of view.

Used to increase magnification, attaches directly to your eyepiece. For example, using a 20mm eyepiece on a telescope with a 200mm focal length, a 2x Barlow boosts magnification from 10x to 20x. This lens effectively doubles your eyepiece range, transforming a 32mm, 26mm, and 10mm set into 16mm, 13mm, and 5mm magnifications. It’s a cost-effective way to enhance your viewing options. Be sure to choose a Barlow with a barrel size that matches your eyepiece diameter, typically 1.25" or 2".

A diagonal redirects light to the eyepiece, making the view more comfortable by adjusting the image orientation. According to optical principles, diagonals are divided into two main types:

• Mirror Diagonal:

Mirror diagonals use a flat mirror to reflect light 90 degrees to the eyepiece, resulting in an upside-down or horizontally mirrored image. While they are widely used, mirror diagonals require more maintenance than prism types due to the need for mirror cleaning and alignment.

• Prism Diagonal:

Prism diagonals use prisms instead of mirrors to reflect light. There are various types of prisms, such as Porro prisms, which provide high light transmission and minimal distortion. Erecting prisms, like the Pentaprism, offer an upright image, ideal for terrestrial viewing, though they can reduce light transmission. Other types, like Dove prisms and Amici prisms, may also be used for specific optical effects or improved alignment.

 

A finder scope is a small telescope that helps locate celestial targets with a lower magnification than the main telescope. It is usually mounted parallel to the main telescope tube, aligned to point in the same direction.

Another popular type of finding aid is the Reflex Sight, which uses an illuminated red dot or crosshair to guide your view to the target. Reflex Sights, however, do not gather light, which can make them less effective in light-polluted areas or when locating faint objects.

Selecting the right camera for astrophotography can be daunting, especially with the variety of options available. This guide will break down the key factors to consider, helping you find the perfect match for your needs.

• DALR vs. Astro Camera

The first decision is whether to use a DSLR (Digital Single-Lens Reflex) or a dedicated astronomy camera.

DSLR Cameras are versatile and widely available. They can be used for general photography in addition to astrophotography, making them a cost-effective choice for beginners. However, they may lack advanced features like cooling and high sensitivity to certain wavelengths, such as hydrogen-alpha (Hα), which is crucial for capturing deep-sky objects like nebulae.

Dedicated Astronomy Cameras are designed specifically for astrophotography, these cameras offer features like active cooling, higher sensitivity, and the ability to shoot in monochrome. While they are more expensive and require additional accessories, they deliver superior results, especially for deep-sky imaging.

• Sensor Type: CMOS vs. CCD

CMOS sensors: Common in modern astrophotography cameras due to their sensitivity, low noise, and relatively lower cost. They are ideal for both planetary and deep-sky imaging.

CCD sensors: Known for high sensitivity and low noise, CCDs were once the preferred choice for astrophotographers but are now less common as CMOS technology has advanced. CCDs are typically more expensive and often require additional processing.

• Sensor Size

The sensor size determines the camera's field of view (FOV) and sensitivity to light. Common sizes include:

	Full Frame	APS-C	Micro 4/3	Planetary
Sensor Size	36 × 24 mm	23.5 × 15.6mm	17.3 × 13mm	6~8 × 4~6mm
Diagonal Size	43.3mm	28.2mm	21.6mm	7~10mm
Features	Excellent balance of field of view and resolution. These sensors perform well in low light, making them great for capturing deep-sky objects.	Smaller and more affordable. Their smaller size effectively narrows the FOV, which is great for capturing smaller objects like galaxies.	Compact and lightweight. Suitable for hobbyists or those using portable setups.	For capturing planets, the Moon, and the Sun. Perfect for short exposures and stacking.
Example	ZWO Asi6200 Sony A7 Canon EOS R5	ZWO Asi2600 Sony A6000 Canon EOS 90D	Olympus OM-D ZWO Asi294	ZWO Asi120 QHY5III

$\text{FOV (arcminute)} \approx \frac{\text{Sensor Size (mm)} \times 3460}{\text{Telescope Focal Length (mm)}}$

For a more detailed explanation of the principles behind FOV calculation, please refer to Telescope Field of View (FOV) Calculation.

• Resolution (Megapixels)

The sensor size defines the physical dimensions of the imaging area on the camera's sensor, while the resolution refers to the total number of pixels in the sensor. The formula is:

$\text{Resolution (pixels)} = \frac{\text{Sensor Size (mm)}}{\text{Pixel Size (mm)}}$

For a sensor, this calculation is applied separately to its width and height. For example, with a full-frame sensor (36 × 24 mm) and a pixel size of 4.3 μm, the resolution would be approximately 8372 × 5581 pixels.

• Pixel Size

In astrophotography, choosing the right pixel size depends on matching your camera to your telescope's focal length and the seeing conditions. The following formula will help you determine pixel size:

$\text{Pixel Scale (arcseconds/pixel)} = \frac{\text{Pixel Size (μm)} \times 206}{\text{Telescope Focal Length (mm)}}$

Pixel Scale indicates the angular area of the sky covered by a single pixel on your camera sensor.

For typical seeing conditions, aim for a Pixel Scale between 1 and 2.5 arcseconds/pixel. Staying within this range helps balance detail capture without over or under sampling.

For more insights on aligning resolutions, check out Matching Resolutions in Astrophotography.

• Cooling System

Cooled cameras reduce sensor temperature to minimize thermal noise, essential for long-exposure astrophotography. This is particularly helpful when capturing faint deep-sky objects. Cooling systems can lower temperatures by 30–40°C below ambient, allowing for cleaner images with less grainy interference.

• Monochrome vs. Color

Color (OSC) cameras: One-shot color cameras are easier to use for beginners and capture RGB data in a single exposure. They are a practical choice for planetary or lunar imaging and can work well for many deep-sky targets with less complex processing.

Monochrome cameras are more sensitive and capture more detail in each color channel separately (often with filters for RGB, Ha, OIII, SII). This makes them ideal for deep-sky imaging and more advanced astrophotography.

The above camera buying guide provides only a simple overview. It is recommended to read Peter Zelinka's articles for more detailed information.

When capturing celestial objects, the image quality in every corner of the frame becomes crucial. To meet this demand, astrophotography often relies on optical correction tools:

• Field Flattener

Field flattener is a lens designed to correct edge aberrations in telescopes. Typically positioned between the telescope and the imaging sensor. It ensures that stars and objects at the edges of the field remain as sharp as those at the center, providing a uniform field of focus.

• Focal Reducer - brighter & wider

A focal reducer is a specialized field flattener that not only corrects edge distortions but also shortens the telescope’s focal length. This reduction results in a faster focal ratio (wider aperture), delivering a brighter image and a wider field of view (FOV), which is especially advantageous for capturing larger celestial objects in astrophotography.

• Barlow Lens - zoom in for small objects

A Barlow lens increases the telescope’s focal length, thereby boosting image magnification. This allows you to capture more detailed images of small celestial objects, like planets or lunar features, without modifying the telescope itself. By effectively "zooming in," the Barlow lens enhances image resolution without needing a smaller sensor. However, this increased magnification also demands stable tracking and reduces the field of view, making precise alignment essential when using a Barlow lens in astrophotography.

An autoguiding system is used to keep celestial objects steady in the frame during long exposures. It corrects small tracking errors in the telescope mount, which are common due to Earth's rotation and mechanical limitations. Without autoguiding, objects can drift or blur in the image, especially during long exposure times. It’s important to ensure that the equipment you choose is compatible with your telescope and mount to achieve optimal performance.

Here’s a breakdown of the main components of an autoguiding system and what to consider when choosing them:

The guide scope is a small, low-magnification telescope mounted parallel to the primary telescope. It’s used solely for guiding, so a large aperture isn’t necessary, but it should have sufficient quality to focus on guide stars. A common choice is a 30–50mm guide scope, with focal lengths between 120-250mm, providing a wide field of view to find stars for tracking. Some setups use off-axis guiders (OAG) instead, which use a small prism to pick off light from the main telescope for guiding without needing a separate scope.

The guide camera is attached to the guide scope and captures images of a guide star at regular intervals. The computer software then analyzes these images and calculates any necessary adjustments to keep the mount on target. When selecting a guide camera, look for:

• Sensitivity: A high-sensitivity monochrome camera is generally preferred, as it can detect faint stars and operate effectively under various conditions.

• Pixel Size and Resolution: Smaller pixels improve guiding precision, though most guide cameras will work well if paired appropriately with the guide scope.

A computer or dedicated autoguider processes the guide camera’s images and sends corrections to the mount. For beginners, a laptop with guiding software (such as PHD2 or ASIAIR for ZWO setups) is often used, as it’s user-friendly and compatible with various guide cameras and mounts. Advanced users might consider a standalone autoguider, which integrates camera, guide scope, and guiding software into a single device, simplifying the setup but sometimes limiting flexibility.

The mount is a critical piece of equipment that supports your telescope. There are several types to consider, each with its advantages depending on your needs and level of experience.

• Equatorial (EQ) Mount: Ideal for astrophotography, this mount features two axes – one aligned with the Earth’s rotation axis (RA) and the other for declination (DEC), allowing for precise tracking of celestial objects.

Recommended products: ZWO AM3, Sky-Watcher EQ6-R

• Sky Tracker: A portable, lightweight option for capturing long-exposure astrophotography. It moves in sync with the Earth's rotation to keep stars sharp during exposures.
Many sky trackers feature a ball mount design, which is suitable for supporting lightweight camera lenses and allows for full-angle adjustments. However, their load capacity may be insufficient for heavier equipment. It is recommended to use a declination (DEC) adapter when mounting a telescope.

Recommended products: iOptron SkyGuider Pro

• Fluid Head: Common in video or camera mounts, it provides smooth, controlled motion, making it suitable for visual observation or wide-field astronomy.

• Altazimuth Mount: Offers simple up-and-down, left-to-right movement, perfect for beginners who want a more intuitive setup.

In addition to understanding the types of mounts, you can evaluate mount products based on the following specifications:

• Head Type Make sure the mount head is compatible with your telescope’s size and weight. Common head types include Vixen-style and Losmandy-style, each designed for different mounting systems.

• Tracking Accuracy For astrophotography, look for mounts with high tracking accuracy, often measured by "arc seconds." The higher the accuracy, the smoother your celestial object tracking will be. An EQ mount with a motor or computerized tracking system will provide the best performance.

• Payload Capacity The mount should be able to support the weight of your telescope, eyepieces, and other accessories without instability.

The tripod supports the mount and provides stability, making it an equally important component of your setup.

• Compatibility with Mount: Ensure the tripod is compatible with your chosen mount. Some tripods are designed specifically to work with certain mounts, so be sure to check the specifications before purchasing.

• Material: Tripods are typically made from aluminum or carbon fiber. Aluminum tripods are heavier but more affordable, while carbon fiber tripods are lighter and more durable, though they come at a higher price point. The choice depends on your preference for portability and stability.

• Leg Spikes: Many tripods come with adjustable leg spikes for stability on soft ground, such as grass or sand. These are typically made from steel, offering better grip. Some tripods allow you to replace the spikes with rubber feet for use on harder surfaces.

• Adjustable Height and Leg Locks: A tripod with adjustable height lets you set your telescope at a comfortable viewing level. Look for leg locks that are easy to use and secure, ensuring the tripod remains stable during observations.

The above provides a brief guide to help you choose a telescope and its accessories. The knowledge surrounding this topic is vast and cannot be fully covered here. You can explore further by researching the specialized terms mentioned in this article. As for how to set up and use a telescope, our website offers many detailed articles to guide you through the process.