Telescope eyepieces are the most important accessory for any visual telescope setup because they determine the magnifying power at which you're viewing. Change the eyepiece and you can bring an object closer or widen the field of view to observe a larger area of sky. Telescope eyepieces are available in a wide variety of designs, sizes, and prices, and OPT is more than happy to help you find which kind of eyepiece is best suited to your individual needs and preferences. Check out this Guide on Choosing the Right Telescope Eyepieces!
Telescope eyepieces are the most important accessory for any visual telescope setup because they determine the magnifying power at which you're viewing. Change the eyepiece and you can bring an object closer or widen the field of view to observe a larger area of sky. Telescope eyepieces are available in a wide variety of designs, sizes, and prices, and OPT is more than happy to help you find which kind of eyepiece is best suited to your individual needs and preferences. Check out this Guide on Choosing the Right Telescope Eyepieces! The addition of the correct eyepiece to a visual astronomy system can drastically improve your astronomy experience, and possession of a wide variety of eyepieces can turn a single high quality scope into a powerful beast capable of viewing almost any target with no more than a change of eyepiece. The versatility and added power that a solid set of quality eyepieces can add cannot be overstated, and sometimes must be seen to truly be believed.
Crafted by Georg S. Plossl in the 1890s, the Plossl eyepiece design consists of two sets of doublets, in a 4-element design, which provide an approximate 50 degree field of view. Although it has a relatively short eye relief, the Plossl eyepiece delivers quality views of deep space and planetary subjects at all focal ratios. It remains one of the most highly regarded of all telescope eyepiece styles, and it's considered an excellent performer for all-around use.
'Electronic Eyepiece' is in fact a term referring to eyepieces that are either cameras, or electronically aided. There are also cameras that are suitable for use as eyepieces, which are great for those who want to easily adapt their system for imaging use. This can also mean eyepieces that have inbuilt illumination, or other technologically advanced eyepieces.
We offer packaged kits of various eyepieces, conveniently providing a full array of different magnifications and powers in one place. This let's you find numerous eyepieces that are all compatible with your telescope in one place. There's a very good reason to have numerous eyepieces as well: Each one is a different magnification and power, meaning that each one produces different views with your telescope, and is better for different targets. Having a full kit gives you the luxury of changing eyepieces as you change targets to tailor your experience for maximum enjoyment.
Eye relief (ER) is the distance your eye must be from the eyepiece lens to achieve focus. This is of importance to eyeglass wearers, who will likely prefer longer lengths to be comfortable, such as something over 15mm. This is a matter of comfort, however, and that comfort level is different for everyone. There are many who like long focal lengths who do not wear glasses while observing. If you are a first timer or are not very familiar with this factor, it is better to err on the side of long than short. Short eye relief will have your eye very close to the lens to focus.
Some eyepieces are designed with reticles on the lens or overlaid in the optical train of the eyepiece. These eyepieces are excellent for pursuits like polar alignment or guiding of any kind. They are also great for use with a finderscope to help you perfectly hone in on your desired target, providing a similar benefit to a crosshair. In general, these eyepieces will be most well suited to cases where accuracy is of the utmost importance.
Some eyepiece designs are best identified by their extremely wide field of view, which renders them excellent for deep sky astronomy. These eyepieces let you truly immerse yourself in the night sky, opening the doorway for you to witness truly stunning views of the night sky. It becomes possible to bear witness to broad swathes of stars in the sky, and a quality wide field eyepiece will be clear to the edge of field when doing so.
Ultra-Wide eyepieces are classified as those that go even beyond what is considered a wide field eyepiece, into a whole new level of immersive beauty. They tend to be over 82 degrees in field of view, and can be in the hundreds. These monstrously powerful eyepieces are similar in application to normal wide field eyepieces, but simply more so in most respects. These are the real heavyweights.
Some eyepieces are designed to be able to 'zoom' in and out, altering their magnification level through adjustment of the eyepiece. This permits one eyepiece to fill the roll of many, and is remarkably convenient for when you have numerous targets you want to observe in a single night. Zoom eyepieces are very cost effective due to this immense flexibility.
Are telescope eyepieces universal?
Eyepieces come in many different shapes and sizes, but when it comes to attaching them to a telescope or diagonal, there are 3 main telescope eyepiece sizes: 0.965", 1.25", and 2". These sizes are determined by the diameter of the eyepiece barrel that fits into the telescope.
How do telescope eyepieces work?
Both a telescope and your eye focus light to a point. Placing an eyepiece at the focal point of a telescope then creates a light beam which is neither converging nor diverging. Your eye can then focus the light beam exiting the eyepiece.
With an eyepiece you can:
- produce and allow you to change the telescope's magnification
- produce a sharp image
- provide comfortable eye relief (the distance between your eye and the eyepiece when the target is in focus)
- determine the telescope's field of view: apparent
- how much of the sky, in degrees, is seen edge-to-edge through the eyepiece alone (specified on the eyepiece; true or real)
- how much of the sky can be seen when that eyepiece is placed in the telescope.
Which telescope eyepiece is best?
With a variety of different eyepieces and sizes, which one is the best for your telescope? Our guide on choosing the right telescope eyepieces will help you figure out which eyepiece is best for you.
How many telescope eyepieces do I need?
Although there is no specific number of eyepieces you should own, with a few different telescope eyepieces, you have a better chance of hitting the optimal power for the particular object you are observing, given the sky conditions at the time. A good starting point is to have a low magnification (25mm or 30mm), mid magnification (15mm-18mm), and a high magnification (9mm or shorter) eyepiece.
How to calculate telescope eyepiece magnification. How do I know what my telescope magnification is?
The following formula will help you determine the magnification based on your eyepiece and telescope's specifications:
Magnification = Telescope Focal Length (mm) / Eyepiece Focal Length (mm)
For example: A 20 mm eyepiece on a 2000 mm telescope (2000/20) gives you 100 power (100x). This makes objects appear 100 times closer to you through the telescope than they appear to your unaided eye.