Let’s take a look at the best type of binoculars to get you started with your astronomy adventure!
Introduction
While telescopes are often the first tool that comes to mind for your astronomical viewing, binoculars can be an excellent and often overlooked option for both beginners and experienced astronomers. This guide will explore the intricacies of choosing the right pair of binoculars for astronomy and discuss the essential accessories that can enhance your observations.
Understanding Binocular Specifications
Before delving into the selection process, it’s crucial to understand the basic specifications of binoculars and how they relate to astronomical viewing.
Magnification and Objective Lens Diameter
Binoculars are typically described by two numbers, such as 7×50 or 15×70. Let’s break down what these numbers mean:
1. Magnification (first number): This indicates how many times closer an object will appear compared to the naked eye. For example, in 7×50 binoculars, objects will appear 7 times closer.
2. Objective Lens Diameter (second number): This number, given in millimetres, represents the diameter of the front lenses. In 15×70 binoculars, the objective lenses are 70mm in diameter.
Choosing the Right Magnification
For astronomical purposes, a magnification between 7x and 10x is generally recommended.
Lower magnifications (7x-8x):
- Offer a wider field of view, making it easier to locate and observe larger celestial objects like star clusters or the Milky Way
- Easier to hold steady without a tripod
- Ideal for scanning the night sky and observing large-scale objects
Higher magnifications (9x-10x):
- Provide more detail on smaller objects like planets or double stars
- May require additional support (like a tripod) for stable viewing
- The narrower field of view, which can make it more challenging to locate objects
Larger magnification (20x-30x):
- Recommended if you want to see crators of the Moon in more detail
- A heavy duty tripod is recommended for stable viewing and to support the weight
- Very narrow field of view and is the hardest binocular to locate objects in the night sky
Powerful astronomical binoculars with higher magnification excel at observing the Moon and planets up close. However, these larger instruments require a sturdy tripod to support their considerable weight.
Keep in mind, it is important to note that higher magnification doesn’t always mean better views. Factors like image stability, field of view, and light-gathering ability are equally important for enjoyable astronomical observations.
Selecting the Appropriate Objective Lens Size
The size of the objective lens is crucial for astronomy because it determines the binoculars’ light-gathering ability. Larger lenses gather more light, which is essential for observing faint celestial objects.
50mm lenses:
- Excellent light-gathering ability
- Ideal for astronomical use, especially in dark sky conditions
- Can reveal fainter stars and provide brighter images of deep-sky objects
- Tend to be heavier and may require support (like a tripod) for extended viewing
Larger lenses (70mm to 100mm):
- Exceptional light-gathering ability
- Can reveal very faint objects and provide detailed views of deep-sky objects
- Usually require a heavy duty tripod or mount due to their weight
- More expensive and less portable than smaller options
Key Factors to Consider
When choosing binoculars for astronomy, several factors come into play beyond just magnification and objective lens size:
1. Exit Pupil
The exit pupil is the diameter of the beam of light that leaves the eyepiece. It’s calculated by dividing the objective lens diameter by the magnification. For example, 7×50 binoculars have an exit pupil of 7.1mm (50 ÷ 7 = 7.1).
- A larger exit pupil (around 7mm) is better for low-light conditions and astronomical use
- The human eye’s pupil dilates to about 7mm in darkness, so an exit pupil of this size maximises the light entering your eye
- Younger observers may benefit from larger exit pupils, while older observers might not see much difference beyond 5mm due to age-related pupil dilation limitations
2. Field of View
The field of view (FOV) is the width of the area you can see through the binoculars, usually measured in degrees or metres per 1000 metres.
- A wider FOV makes it easier to locate and track celestial objects
- Lower magnification generally provides a wider FOV
- For astronomy, a FOV of 5-7 degrees is considered good, while 7-10 degrees is excellent
3. Eye Relief
Eye relief is the distance from the eyepiece where you can still see the full field of view.
- Longer eye relief (15mm or more) is more comfortable, especially for eyeglass wearers
- It allows you to hold the binoculars farther from your eyes without losing the full FOV
- Crucial for extended viewing sessions and overall comfort
4. Optical Quality
The quality of the optics significantly affects the image you see. Look for:
- Fully multi-coated lenses: These reduce light loss and glare, providing brighter and sharper images
- BAK-4 prisms: Offer better light transmission and edge-to-edge sharpness compared to BK-7 prisms
- Phase correction coating: Improves contrast and resolution in roof prism binoculars
5. Lens Coatings
Look for fully multi-coated optics for the best light transmission and image quality
6. Prism Types:
Roof prisms are more compact but require more expensive materials and coatings for comparable performance
Porro prisms typically offer better optical quality at lower prices
7. Weight and Size
Consider how comfortable the binoculars are to hold for extended periods.
- Heavier binoculars (like 20×80 or larger) may require a strong tripod for extended viewing
- Lighter models (like 8×42) are more suitable for handheld use and travel
- Consider your intended use and physical comfort when choosing
Recommended Binoculars for Astronomy
Here are some popular choices for astronomical binoculars, along with their strengths:
1. 7×50 binoculars:
- Excellent for wide-field views of star fields and larger deep-sky objects
- Easy to hold steady, great for beginners
- Ideal for observing the Milky Way, large open clusters, and comets
- Example: Saxon 7 x 50 Wide Angle Porro Prism binoculars
2. 10×50 binoculars:
- Offer more magnification while maintaining good light-gathering ability
- Good for observing lunar details, larger planets, and double stars
- May require support for stable viewing
- Examples: Pentax SP 10×50 Porro Prism, GPO Passion HD 10 x 50 binoculars
3. 15×70 binoculars:
- High magnification and large aperture for detailed views of deep-sky objects
- Require a tripod or parallelogram mount for stable viewing
- Excellent for observing star clusters, nebulae, and galaxies
- Examples: Celestron SkyMaster 15×70, Saxon Night Sky 15×70 Astronomical Binoculars
4. 20 x 80 or 25 x 100 binoculars:
- These are big! Higher magnification and very large aperture for detailed views of deep-sky objects
- Definitely requires a strong tripod for stable viewing
- Ther best viewing for observing star clusters, nebulae, and galaxies
- Examples: Saxon NightSky Binoculars 25×100, Saxon 30×80 Astronomical Binoculars
Essential Accessories for Astronomical Binoculars
To enhance your stargazing experience, consider the following accessories:
1. Tripod
- Helps to stabilise your view, especially with higher magnifications or heavier binoculars
- A sturdy tripod with a smooth pan head is ideal for astronomical use
- For lighter binoculars, a lightweight tripod can provide adequate support while maintaining portability
- Example: Celestron Trailseeker Fluid Pan Tripod
2. Red Flashlight:
- Preserves your night vision while allowing you to read star charts or adjust equipment
- Look for adjustable brightness and a comfortable grip
- Most torches offer both red and white light options
- Head lamp style is good because it allows your hands to be free while using the charts and engaging with the equipment.
- Example: Saxon Red LED Astronomy Flashlight
3. Star Charts or Planisphere:
- Helps you navigate the night sky and identify celestial objects
- A planisphere is particularly useful as it shows the visible sky for any date and time
- Consider laminated charts for durability in damp conditions
Star Disc – Double Sided Planisphere
4. Smartphone Apps:
Apps like Stellarium, Sky Map, or Star Walk can assist in locating objects and provide information about what you’re observing
- Many apps offer a night mode with a red screen to preserve dark adaptation
- Some advanced apps can control computerised mounts for precise pointing
5. Lens Cleaning Kit:
- Keeps your optics clean for optimal viewing
- Should include lens cleaning solution, microfibre cloths, and a blower
- Regular cleaning maintains the quality of your views and prolongs the life of your binoculars
Saxon Optical Lens Cleaning Kit
6. Observing Chair:
- Provides comfort during long observing sessions
- Adjustable height models allow for comfortable viewing at various angles
- Look for sturdy construction and portability
7. Warm Clothing:
On a clear night, the night air temperature can get very cold, so keep nice and warm 🙂
Conclusion
Choosing the right pair of binoculars for astronomy can greatly enhance your stargazing experience. By considering factors such as magnification, objective lens size, optical quality, and additional features, you can find a pair that suits your needs and budget.
Remember, the best binoculars for astronomy are the ones you’ll use regularly. Start with a pair that fits your requirements and budget, and you’ll be well on your way to exploring the wonders of the night sky. As you gain experience, you may find yourself wanting to upgrade or expand your equipment, but even a basic pair of binoculars can reveal countless celestial objects and provide years of enjoyment.
Whether you’re observing the craters of the Moon, the moons of Jupiter, the Orion Nebula, or the star clouds of the Milky Way, binoculars offer a wide-field, immersive view of the skies above you that can be both awe-inspiring and educational.
Optics Central has a wide range of Astronomy Binoculars for you to try out and the accessories that are required as well.
https://www.opticscentral.com.au/binoculars/astronomy-night-binoculars.html