Different types of Telescope Eyepiece: An Ultimate Guide

When you are a telescope owner than knowing about the different types of telescope eyepiece is a compulsory matter for you. Since an eyepiece is a lens or mirror which attached to the telescope and without this part a telescope is nothing.

In fact, you are going to invest on an additional telescope eyepiece or have pursued buying your very first telescope. In every situation, you need awareness and wisdom about the distinctive eyepiece as it will make your job easy and efficient. Besides as choosing the finest eyepiece is not so light work since you have to perceive many things regarding in the manner.

Meantime these guidelines skillfully assist you to learn about your topic and capable you to make a final decision. Let’s get started that what you need to look for in your finishing attempt.

Focal length or magnification

This is the biggest principle part of a telescope where actually your selected object image is created. Means whatever you desire to see with your telescope the focal length capacity determinate how you see it clean, big, and bright and so on. It exists on the distance from a primary lens or mirror of every telescope.

The capacity or ability of the focal length is measured in millimeters (mm) that has written in every telescope product details. Usually, the focal length comes in the range from 100mm to 3000mm which is depending on price, lens or mirror size and some other thing.

On the other hand, you can estimate the Lowes and highest magnification from your focal length size. For instance, if your focal length is 1000mm with the eyepiece size of 25mm then it able you to see large or close you object between 15x to 280x. The same eyepiece can be used for a different purpose with the variation of focal length power and capacity. So when you intended to take an eyepiece first check out your focal length measurement.

Field of view

Apart from focal length, the field of view is another important aspect of a telescope. Like the focal length and magnification feature, the field of view also has written on the telescope packing details. In case, focal length measured in millimeter whereas the field of view measured in degree.

You can easily figure it out within your eyepiece where it has penned. An eyepiece field of view can vary for the smallest 20 degrees to wide 300 degrees depending on the device price and other feature. The narrow fields of view (20 to 70) are used for focusing a small portion of sky or territory while larger (80 to 300) are for maximum wide viewing.

Besides there are deep relationships exist between the magnification and focal length with the field of view. For instance, if an eyepiece has a field of view of 80 degrees and you are using 100x magnification then the actual field of view will be 0.8 degrees. So calculating the relations between eyepieces focal length and field of view is important for estimated your telescope expanse.

Telescope eyepiece size

The physical size of telescope eyepiece is a fact while choosing an additional eyepiece or the main one. Many think, the size of an eyepiece is not a big deal and overlook it. But this is a curial factor that as important as focal length or field of view.

The maximum of eyepiece now a day appeared in two different sizes. The measurement of this size is known as barrel diameters. Therefore, the latest length of the eyepiece appears in 1.25 inches and 2 inches. Although many telescope manufacturer offers 0.965 eyepieces those are now thing of past and now the majority are coming in 1.25 to 2 inches.

However, 1.25 inches eyepieces are generally designed for standard viewing that comes under 50 to 200$. Means you will find them at an affordable price. On the other hand, 2 inches offer you to gather the wide and greater view of an object that comes under 300 to 500$ depending on other feature and functionally. In case of choosing it is wise first to find out your desired field of viewing than go for eyepiece size.

Eye relief

Eye relief basically comes in different form and name that remains in telescope optical part. It is the distance between your eye and the telescope eyepieces. It works for maintaining your comfort zone, relaxing and give space in your viewing experience and became more important for a person who used to wear glasses.

By the way, the shorter eyepiece is not a wise choice as it makes a barrier in your close viewing. It is always better you took an eyepiece with (15mm to 20mm) minimum that helps you to view your object without any problem.

The popular and well organized some eye reliefs are Plossl, Orthoscopic, Kellner and Super Plossl. Although there many out of the name we have mention but these are familiar and provide enough good service in case of telescope eyepieces.

Eyepiece Exit Pupil

Exit Pupils is also known as Aperture exit that determinate how clean, big or bright image you can view through your telescope eyepieces. Actually the big the aperture size is you can get a more clean and dashing image.

For knowing your eyepiece Exit pupil normally divided the focal length with the aperture size and you will easily get the exit pupil. You can also check the product detail as most of the manufacturer pointed it on the product details. The stranded exit pupil size comes in 4mm to 10mm yet it deepening on the other feature of the telescope. 

Eyepiece coating

Many telescope eyepieces come in different type of coating technology. For example, blue film, green film, anti-reflection coating, eye protective coating, glare to chromatic aberration reduction and some more. It is not so important factor but for extra convenience and get exact perfect one checking this feature might help you.

Final words

Investing on a telescope eyepiece is not so light work as you might though. But this details description of eyepiece feature and functionally as we have mentioned above might help you in your way of selection. We hope you got enough knowledge about telescope eyepiece component and performance that lead you to deal with confidently and profitably.

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