The Basics of Telescope Eyepieces Explained | Alien Tech

[Music] hey guys welcome to the channel if you are considering buying a telescope then at some point in your astronomy journey you will need to buy some eyepieces to get the best result while buying a telescope aperture size is one of the most important factors but if you want to get the most out of your telescope then you also need better eyepieces your telescope is as good as its eyepiece is what does that mean exactly during stargazing you can't see the planets and galaxies with the same magnification for example let's say you have a celestron 8se telescope now with this telescope you can observe planets and some deep space objects but for seeing the planets and deep space objects you cannot use the same eyepiece if you use the planet's eyepiece for deep space then it might not give excellent results for deep space and vice versa so choosing a nice piece is very important to get the most out of your telescope when you buy a cheaper telescope the eyepieces which come with it are not of the best quality but they do get the job done sometimes by just changing the eyepiece you get sharper and better images of the sky which might make you feel like you bought a new telescope so choosing the right eyepiece is very important while choosing an eyepiece you need to consider its focal length high relief field of view barrel size and exit pupil focal length or magnification this is also known as the power of an eyepiece more magnification means higher power eyepiece and vice versa your telescope collects the light and the magnification is done by an eyepiece just like your telescope has a focal length similarly your eyepiece also has a focal length to calculate the total magnification of an eyepiece the simple formula is focal length of telescope divided by the focal length of an eyepiece let's say you have a telescope that has a focal length of 2000 millimeters and you're using a 10 millimeter eyepiece then your highest magnification can be 2 000 divided by 10 equals 200 times but when you use a 25 millimeter eyepiece then the highest magnification you get is 2 000 divided by 25 equals 80 times while choosing your eyepiece you should keep magnification between 40 to 50 times per inch of the telescope's aperture that means if you have a 6 inch aperture telescope then your maximum magnification should be between 240 times to 300 times if you live in an area where the skies are very clear then you can go for 50 to 60 times magnification per inch eye relief what exactly means eye relief eye relief is the distance between the eyepiece and your eyes the higher focal length of an eyepiece has higher eye relief and the lower focal length eyepieces usually have lower eye relief for example if you're using a 10 millimeter lens that has a 5 millimeter eye relief then it is very difficult for someone with glasses to get a clear image through the telescope similarly if you're using a 40 millimeter eyepiece that has 20 millimeter eye relief it is easier to use so if you are someone who wears glasses then eye relief is one of the important factors you should consider while buying an eyepiece some modern low focal length eyepieces will give you higher eye relief regardless of their focal length but they are a bit expensive field of view eyepieces not only have focal length but they also have a field of view it is measured in degrees it tells you the width of the sky your eyepiece can cover while focusing eyepieces have two fields of view apparent field of view and true field of view an apparent field of view is the width of angle of the view through the eyepiece before it is paired up with a telescope this is the field of view used for marketing and advertising these eyepieces but you're not going to look just through your eyepiece without pairing it with the telescope so you need to calculate the true field of view the true field of view is the width of the view when it is paired with a telescope that's why it's called the true field of view a large apparent field of view means more sky width is covered simple eyepieces usually have 40 to 45 degrees of apparent field of view while the wide field design has more than 60 degrees of apparent field of view sometimes more important is the true field of view any combination of telescope and eyepiece has a specific true field of view the true field of view quantifies the amount of sky visible in a particular scope with a particular eyepiece for example if a particular telescope eyepiece combination provides a one degree true field of view two stars that are separated by exactly one degree will just fit into the eyepiece field with each star on opposite edges of the field a true field of view is obtained by dividing the apparent field of view by magnification of the eyepiece for example consider a 20 millimeter focal length eyepiece of 50 degree apparent field of view in combination with a scope of 1 000 millimeter focal length the magnification will be 50 times and the true field will be 50 degree divided by 50 times as one degree here's an example of true field of view of the orion nebula when it is seen with a telescope of 1 000 millimeter focal length and three different eyepieces each eyepiece has a 20 millimeter focal length but a different apparent field of view 50 degrees 68 degrees and 80 degrees each eyepiece gives the same magnification but the eyepieces with the larger apparent field of view show a larger angular area of the sky barrel size eyepieces are made with barrel sizes designed to fit standard telescope focusers majority of the telescopes have a focuser size of 1.25 inches so the most common size of the eyepiece is 1.25 inches they're also large diameter 2 inch eyepieces which show more of the sky but 2-inch eyepieces are more expensive to produce than 1.25 inch models a telescope with a 1.25 inch focuser will accept only a 1.25 inch barrel size eyepiece and a telescope with a 2-inch focuser will accept only a 2-inch barrel size eyepiece if you want to fit a 1.25 inch eyepiece on a 2-inch focuser then you will need an adapter while purchasing an eyepiece do keep in mind the focus or size of your telescope so that you can choose an eyepiece with the perfect barrel size exit pupil exit pupil is the diameter of the beam coming out of the eyepiece it determines where you place your eye to view the entire field usually it is measured in millimeters the larger the exit pupil the brighter the image will be under low light conditions exit pupil size is calculated by dividing the eyepiece focal length by the telescope focal ratio our eyes can shrink up to 0.5 millimeters and expand up to 7 millimeters so usually the exit pupil ranges between 0.5 millimeters and 7 millimeters exit pupil size is completely dependent on the individual as you age the expansion of your pupil decrease so anybody who is above the age of 50 should limit the exit pupil to 5 millimeters barlow lens if you want double magnification without buying a new eyepiece then you should consider buying a barlow lens at two times barlow will double the magnification and a three times barlow will triple it barlow lenses usually have a higher focal length so you will also get higher eye relief with the barlow lens you can get two different magnifications with one eyepiece so barlow lens one must have in their eyepiece set so that's it these are some basic things you should consider while buying a new telescope eyepiece there are some eyepieces provided in the description i hope this video helped you to understand the details of the eyepieces if it did then give it a like and subscribe to the channel for more technology related content see you in the next video have a nice day guys peace you

Channel: Alien Tech

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Keywords: telescope eyepieces explained, telescope eyepieces, telescope eyepieces for beginners, telescope eyepieces guide, celestron eyepieces, eyepieces for telescopes, eyepiece, astronomy, telescope, best eyepieces for telescopes, telescope eyepiece types, telescope eyepiece reviews, basics of telescope eyepieces, telescope barlow lens, how to buy telescope eyepieces, telescope eyepiece filters, adjustable telescope eyepiece, telescope eyepiece assembly, Alien tech

Id: TfpJTb1vna0

Length: 7min 32sec (452 seconds)

Published: Mon Jan 18 2021