Crystal – There are a couple of different materials that fit into this category with fluorite crystal being the most common.

This type of glass tends to accompany high-end binoculars and costs more than most of the other types, but it also provides some of the best performance. ED glass accounts for the different wavelengths of light and accommodates them individually.

ED/HD – Extra-low-dispersion glass, also called high-definition glass, is one of the best qualities of glass available.

That said, binoculars with BK7 glass are the least expensive and can work for someone who wants a test-run without commitment. This is because astronomy binoculars already have to deal with difficult conditions from low levels of light in the first place.

BK7 – BK7 is the lowest grade of glass used for binoculars and is not great for stargazing.

That said, this type of glass is generally combined with one of the other two types rather than used on its own.

This means that binoculars with SK15 glass need better coatings but still provide clear, accurate images.

SK15 – SK15 glass is interesting in that it refracts more light than the other two major types, but it incurs less light dispersion.

That said, it is a bit more expensive than most of the other types as well.

BAK4 – This type of glass uses a finer grain of molecule which reduces the amount of light scattering and leads to superior image quality.

While the objective lens, the magnification, and other factors can influence image sharpness, nothing beats out the quality of the glass for performance impact. The quality of the glass determines more about the image quality than anything else.

Even better, this kind of prism does not require as many coatings. One of the best qualities of Porro prisms is that they cost less than roof prism arrangements. Porro – Porro is an offset aligned prism arrangement which inherently increases the size of the binoculars, but given astronomy binoculars are already large and are often mounted on tripods, the weight and size may be less of a concern.Additionally, this kind of prism alignment suffers more from refraction than porro. That said, roof prisms are more difficult to make which increases the cost of binoculars using them.

But keep in mind that astronomy binoculars are almost always larger than average binoculars, so a roof prism might provide a slightly less bulky option. Roof – Roof prisms are the more compact of the two, which makes them good for a smaller device.The prism arrangement generally does not impact the quality of the image, but it does impact the price and size of the binoculars. Prisms rectify inverted images seen through the binoculars. Minimally, astronomy binoculars should have 70-mm objective lenses, but ideally, stargazing binoculars should offer objective lenses that are closer to 100-mm in diameter. The objective lens is the lens at the end of the binoculars and ultimately determines how much ambient light enters the binoculars.īecause astronomy binoculars are used during the night time, they need all the ambient light that they can get.

While this is not always the most important factor to consider for binoculars in general, it is crucial when gauging binoculars for stargazing. We cover some options in our overall binocular guide, but here we focus on devices specific to astronomy. It’s important to understand what makes a particular model the right choice for you. Astronomy binoculars are a great alternative and offer a highly enjoyable stargazing experience without the bulky equipment. But telescopes are large, expensive, and require a lot of setup time. When it comes to stargazing, most people think a telescope is required to enjoy the beauty of the cosmos.

Binocular for stargazing