If you’re new to astronomy, you might wonder what are the 2 types of telescopes. It’s the most basic way to categorize how they gather light. Understanding this simple split is the first step to choosing the right one for you.
It all comes down to the primary element that collects light from distant stars and galaxies. This choice defines the telescope’s design, its strengths, and its typical uses. Let’s look at the two fundamental families.
What Are The 2 Types Of Telescopes
The two primary types are refracting telescopes and reflecting telescopes. Refractors use lenses, while reflectors use mirrors. This core difference leads to all other variations in how they are built and perform.
Each type has a long history and a dedicated following among stargazers. Your preference might depend on what you want to observe, your budget, and how much maintenance your willing to do. We’ll break down each one in detail.
Type 1: Refracting Telescopes (Refractors)
A refracting telescope uses a large objective lens at the front of the tube to bend (refract) light to a focus point. This is the oldest telescope design, famously used by Galileo. The lens gathers light and directs it to the eyepiece at the back.
The simple, sealed tube makes refractors very durable and low-maintenance. They are excellent for viewing the Moon, planets, and double stars. Their design provides high contrast and sharp images.
How a Refractor Telescope Works
Light enters the front of the tube and passes through the objective lens. This lens is convex, meaning it curves outward. The light rays are bent inward as they pass through the glass.
They converge at a focal point inside the tube. An eyepiece lens then magnifies this focused image for your eye to see. The distance from the lens to the focal point is the focal length.
Key Advantages of Refractors
- Low Maintenance: The optical tube is sealed, so dust and moisture rarely get inside. The lens rarely needs cleaning or alignment.
- Sharp, High-Contrast Images: The lens design delivers crisp views, perfect for planetary details like Jupiter’s bands or Saturn’s rings.
- Durable and Robust: The simple design has fewer parts that can get out of adjustment, making them great for beginners.
- Quick to Set Up: They are often ready to use almost right out of the box with minimal setup required.
Common Drawbacks of Refractors
- Chromatic Aberration: This is a color fringing effect where different colors of light focus at slightly different points. It can create purple halos around bright objects. Higher-end models use special extra-low dispersion (ED) glass to correct this.
- Cost and Size: Large, high-quality lenses are very expensive to manufacture. For the same aperture (light-gathering ability), a refractor will typically cost more and be longer than a reflector.
- Weight: Large glass lenses can make the telescope quite heavy, requiring a sturdy mount.
Type 2: Reflecting Telescopes (Reflectors)
A reflecting telescope uses a large, curved primary mirror at the bottom of the tube to gather and focus light. This mirror reflects the light back up the tube to a secondary mirror. The secondary mirror then directs the light out to the eyepiece on the side.
This design was invented by Sir Isaac Newton, and many reflectors are called Newtonian telescopes. They are the most popular design for amateur astronomers because they offer a lot of aperture for your money.
How a Reflector Telescope Works
Light travels down the open tube to the primary mirror at the bottom. This concave mirror reflects the light back up, converging it. Before the light reaches its focus, a small, flat secondary mirror (mounted at an angle) intercepts it.
This secondary mirror reflects the focused light out through a hole in the side of the tube. Finally, the eyepiece magnifies the image. The focal length is determined by the curve of the primary mirror.
Key Advantages of Reflectors
- Best Aperture for Your Budget: Mirrors are cheaper to make than large lenses. This means you can get a much larger light-gathering telescope for the same price as a smaller refractor.
- No Chromatic Aberration: Since mirrors reflect all colors of light the same way, there is no color fringing. Images are naturally color-accurate.
- Excellent for Deep-Sky Objects: The large aperture is ideal for gathering the faint light from galaxies, nebulae, and star clusters.
- Compact Design for Aperture: The light path is “folded,” so a long focal length can be fit into a shorter tube.
Common Drawbacks of Reflectors
- Regular Maintenance: The open tube can collect dust on the primary mirror. The mirrors also occasionally need collimation, which is the process of aligning them perfectly.
- Bulk and Weight: While shorter, large-aperture reflectors can be very bulky and heavy, with big tube diameters.
- Central Obstruction: The secondary mirror and its supports block a small amount of incoming light and can slightly reduce contrast compared to a refractor of similar quality.
- Cool-Down Time: Large mirrors need time to reach the outdoor air temperature; otherwise, tube currents can blur the image.
Comparing Refractors vs. Reflectors Side-by-Side
To make the choice clearer, here’s a direct comparison of key factors. This should help you see which type aligns with your main interests.
Best Use Cases
- Choose a Refractor if: Your primary interest is the Moon and planets. You want a grab-and-go telescope with minimal fuss. You prefer sharp, high-contrast views and don’t mind a smaller aperture for the price.
- Choose a Reflector if: Your primary interest is faint deep-sky objects like galaxies. You want the largest aperture possible for your budget. You are comfortable with occasional maintenance like collimation.
Cost and Value
For a beginner’s budget (under $500), a reflector will almost always give you more aperture. You might get a 6-inch or 8-inch reflector for the price of a 3-inch or 4-inch quality refractor. The reflector wins on pure light-gathering power per dollar.
Ease of Use and Maintenance
Refractors are the clear winner here. They are typically ready to observe faster, stay clean longer, and never need optical alignment. A reflector requires a bit more patience and learning, especially for collimation, but it’s a simple skill to pick up.
A Third Category: Compound Telescopes
While the question “what are the 2 types of telescopes” refers to the basic optical designs, modern astronomy often includes a third hybrid type. Compound telescopes, like Schmidt-Cassegrains and Maksutov-Cassegrains, use a combination of lenses and mirrors.
They fold the light path multiple times, resulting in a very compact tube. This makes them extremely portable and versatile. They are excellent all-rounders, good for both planets and deep-sky viewing, though often at a higher price point than a comparable reflector.
How to Choose Your First Telescope
Now that you know the two main types, here are practical steps to pick your first scope. Remember, the best telescope is the one you’ll use most often.
Step 1: Define Your Primary Interest
Be honest about what you most want to see. Is it the rings of Saturn, or the Orion Nebula? Planets and the Moon favor optical quality and contrast (refractors, compound scopes). Galaxies and nebulae favor sheer light grasp (reflectors).
Step 2: Set a Realistic Budget
Your budget must include the mount. A shaky mount ruins any telescope. Spend at least as much on a solid mount as you do on the optical tube. Don’t forget to leave room for a couple of good eyepieces.
Step 3: Consider Portability and Storage
Where will you store it? How far will you carry it? A huge 10-inch reflector is amazing, but if it’s too heavy to move, it will collect dust. A smaller, portable scope used regularly is far better.
Step 4: Understand Aperture is King
The diameter of the lens or mirror is the most important spec. It determines how much light you collect and how much detail you can see. Bigger aperture shows fainter objects and allows for higher useful magnification. Prioritize aperture within reason for your goals.
Step 5: Start with Reputable Brands
Look for brands known for good beginner scopes, like Celestron, Orion, or Sky-Watcher. Avoid department store telescopes that overpromise on magnification. A good starter scope often has an aperture between 70mm (refractor) and 130mm (reflector).
Essential Telescope Accessories
Your telescope is just the start. These accessories will greatly improve your experience. You don’t need them all at once, but plan for them.
- Better Eyepieces: The ones included are often basic. A good Plössl or wide-field eyepiece in a medium focal length (like 15mm) is a great upgrade.
- A Barlow Lens: This doubles or triples the magnification of your existing eyepieces, giving you more options without buying many new ones.
- A Finderscope: A red-dot finder or a right-angle finderscope makes aiming your telescope at specific stars much, much easier.
- Star Charts and Apps: A planisphere or a smartphone app like Stellarium is essential for learning the night sky.
- A Stable Chair: Observing is comfortable when you can sit stably at the eyepiece.
Common Beginner Mistakes to Avoid
Everyone makes mistakes when starting out. Here’s how to sidestep the most common ones, so you have more fun from the begining.
- Chasing Maximum Magnification: The highest power is often blurry and shaky. The best views are usually at medium magnifications. Useful max is about 50x per inch of aperture.
- Ignoring the Mount: A wobbly mount makes observing frustrating. Invest in stability.
- Observing from a Rooftop or Balcony: Heat rising from buildings causes terrible image distortion. Observe from ground level on a lawn if possible.
- Giving Up Too Soon: Learning to find objects takes practice. Start with easy targets like the Moon and bright planets.
- Not Letting the Telescope Cool: Especially for reflectors, let the scope sit outside for 30 minutes before observing for the sharpest views.
FAQ Section
What is the main difference between the two telescope types?
The main difference is the primary light-gathering element. Refracting telescopes use a large front lens. Reflecting telescopes use a large mirror at the bottom of the tube.
Which telescope type is better for a beginner?
It depends. A small refractor is often recommended for its ease of use and low maintenance. However, a Dobsonian reflector (a type of Newtonian on a simple mount) offers the most aperture for the money and is also a fantastic beginner choice.
Can I see planets with a reflecting telescope?
Absolutely. Reflectors show excellent views of planets, especially with good collimation and steady air. For planetary detail, a longer-focal-length reflector works very well.
What is a catadioptric telescope?
This is the technical term for compound telescopes like Schmidt-Cassegrains. They combine lenses (correctors) and mirrors to create a compact optical system. They are a popular third category beyond the basic two types.
Do refractors have any color problems?
Lower-cost refractors can show chromatic aberration, a purple halo around bright objects. This is minimized in models with ED or apochromatic lenses, but these are more expensive. It’s a trade-off for the design.
How hard is it to collimate a reflector?
It’s not as hard as it sounds. With a simple collimation cap or laser tool, it takes just a few minutes once you learn the steps. Many beginners do it themselves after watching a tutorial or two.
Getting Started with Your New Telescope
Once you’ve chosen your telescope based on understanding the two core types, the real fun begins. Start by observing the Moon. Its craters and mountains are stunning at almost any magnification. Next, try bright Jupiter and its moons, or Saturn when it’s visible.
Join a local astronomy club if you can. Nothing beats learning from experienced observers. They can help you with setup, finding objects, and getting the most from your equipment. Remember, patience is key. The sky won’t run away, and every clear night is a new chance to learn.