How to Use a Refractor Telescope

hey everyone I'm John Reed host of learn to stargaze astronomer and author of the things to see with the telescope Series in this video I'm going to show you in detail how to use a refractor telescope on an a mount if you have an equatorially mounted telescope that's one that looks like this and has EQ in the name see our video on that topic I'll post a link in the description below this video is a followup to last year's video on how to use any telescope so if you don't have a telescope yet you might want to check that video out first so here we have a basic refractor telescope these are one of my favorite types of beginner telescopes cuz they're really easy to use refractors use a lens to collect light from space the light then gets refracted or bent by the lens travels down the telescope tube the light then bounces off a diagonal and into an eye piece where it's brought into focus in your eye allowing you to see a magnified version of the object you're observing note that the magnification of the telescope is the focal length of the telescope divided by the focal length in the eyepiece in other words the lower the focal length of the eyepiece the higher the magnification but counterintuitively when observing objects with a telescope lower magnifications are often preferable this is the National Geographic 102mm refractor which I bought at Costco last year for around $200 typically the number in the name of a telescope refers to the aperture that's the diameter of the primary lens the aperture of the telescope determines the resolution of the telescope the larger the aperture the more detailed objects will appear 102 m mm is an extremely popular size for a telescope lens there are 102 mm refractors from several Brands and most of these telescopes are generally pretty good now let's talk about this mount for a moment this is an altaz ofth Mount you may hear it called an AZ Mount which effectively stands for altitude and azoth this simply means that the telescope is designed to move along this axis the azth axis left and right and this axis the altitude axis up and down this also corresponds to how this telescope is used to point at things in the sky as you move the telescope left and right the direction the telescope is pointing is changing in azth in other words the scope is moving parallel to the Horizon the other axis is Altitude this corresponds to how high the telescope is pointed above the Horizon the farthest point above the Horizon is the Zenith a beginner telescope should easily be able to point both at the Horizon and all the way up to the Zenith now this refractor telescope can be moved in two ways first for large mov movements you can simply push the tube to approximately where you want it to go the second way to move the telescope is with fine adjustments these are the slow motion controls they're used to move the telescope with very precise movements and also to help you track objects as they move across the sky this is the finder it's used to help point the telescope at the correct spot in the sky this is a red dot style finder which tend to be included with most beginner telescopes these days these finders take 2032 batteries it's best to have have extra 2032 batteries on hand because if you're unable to use the finder finding things in the sky can be nearly impossible your telescope may have a finder telescope now I find these more challenging to use however they can be helpful in the city because they enable you to see stars that are not visible to the uned eye and they're helpful in Dark Skies when searching for deep Sky objects because often times you can see the Deep Sky object in the finderscope itself in any case if you're just setting up your telescope the first thing you need to do is make sure that the finder and the telescope are pointed at exactly the same spot this is far easier to do during the day than at night and you should check the alignment of your finder every time you use your telescope you're going to start by adding a high focal length low powered eyepiece to the diagonal don't be surprised if the image in the telescope appears backwards in astronomy we call this Mir reversed some refractors come with an erecting eyepiece which uses a prism to flip the image back to normal I found these to be less common and are typically used on telescopes designed for looking at things on earth now if you have a red dot finder turn it on with this knob here then Center the telescope on a distant object like the top of a flag pole a chimney or a street light if you're doing this at night I typically use a bright star you just need to make sure that the telescope and the finder are pointed at the same bright star then use this knob here to move the finder up and down and this knob here to move the finder left and right for finder telescopes these have have three knobs but the process is basically the same when you think you've got the finder lined up with your target move between the telescope and the finder just to confirm that both the finder and the telescope are pointed at exactly the same spot you may also want to take this time to focus the telescope but we'll talk about that later as you'll need to refocus the telescope for looking at space and anytime you switch eyepieces this is the diagonal it contains a mirror or prison to direct light from the telescope into the eyepiece these typically come in two types 90° diagonals and 45° diagonals the 90° diagonals like this one are used for looking at things in space whereas the 45° diagonals like this one are typically used for looking at things on earth if your telescope included a barow I recommend you don't use this for a while barlos are used to increase the focal length of the telescope this increases the magnification but it makes objects in space far more difficult to find typically barlos are used after you've centered a planet in the eyepiece and you're attempting to go in for a closer look this is the focusing knob you'll need to focus the telescope every time you switch eyepieces and often times you may need to refocus the telescope every time you switch users if stargazing with friends this is because some people me includ it like to stargaze without eyeglasses and you're effectively focusing the telescope to your prescription the telescope is in focus when the objects you're observing appear detailed and sharp and the stars in the image are as as small as you can possibly make them speaking of eyepieces which eyepiece should you use typically your telescope comes with two eyepieces one with a high focal length for General observing and a second generally a smaller eyepiece designed for zooming in on planets or craters on the moon regardless of what you're planning to observe you always want to start with the low powerered high focal length eyepiece for example this telescope came with a 25 mm eyepiece this is the eyepiece we'll use for finding our targets and for the most most part this is the eyepiece I'll use for most of my observing if you're observing a planet like Saturn and you want a closer look first find and center of the target with the lower powered eyepiece then remove it and replace it with the higher powered eyepiece at this point you'll need to refocus the telescope with the focusing knobs and most likely reenter the target with the slow motion controls as the object may have drifted across and out of your field of view it's important to note that zooming in with a higher powerered eyepiece although the image will appear Clos will not gain any detail it's sort of like reading a book if you bring the book closer to your face the words will appear larger but it won't make the story any better that said astronomers will often experiment with different eyepieces until they found the view they find most pleasing there is a lot to know about eyepieces and I get asked about upgrades quite a bit the best advice is to get proficient in observing with the eyepieces that came with your telescope before you consider upgrading if you are considering upgrading I recommend recommends simply upgrading to a higher quality eyepiece of the same focal length as the ones that came with your telescope some advice for stargazing and stargazing with refractors in particular stargaze from a chair this is especially helpful if you're observing objects high in the sky make sure you're outside with a clear view of the Horizon telescopes do not work well from inside when pointed through a window you'll also want to be on Solid Ground a deck will transmit vibrations through the tripod and into the eyepiece making image shake and that's just not any fun now that the telescope is in focus and the finder is aligned it's time to start thinking about what you're going to observe and how you're going to find the objects in the sky if you're new to astronomy I recommend starting with the moon which is pretty easy to find assuming that's in the sky at the time the moon is great for learning to focus the telescope and tracking it as it moves across the sky as the phases of the moon changed from night to night there's always something new to see for a deep dive into the lunar craters check out my book 50 things to see on the moon which won the RC Simon Nukem award back in 2020 for planets it's best to use stargazing software like stellarium to determine which planets are visible at a given time and where they'll be in the sky planets like Saturn Jupiter Venus and Mars are a lot of fun to observe and you don't need Dark Skies they'll look the same from downtown in a city as they will from the countryside for other objects like Star clusters nebuli and galaxies a simple Stargate gazing book like 50 things to see with a telescope or a kid's Guide to the night sky is far better than a stargazing app stargazing apps often oversell what you're realistically able to see and some of the Targets in the software require a camera and long exposures to be resolved at all speaking of cameras once you try to attach a camera to your telescope you've left the hobby of stargazing altogether and entered the realm of astrophotography now we talk a lot about astrophotography on this channel but that hobby while addictive can be extremely frustrating and typically far removed from the relaxing night Under the Stars such as the stargazing experience provides as I said the moon and planets can be observed from the city however most objects like galaxies and nebuli require darker skies and the darker the better if you're attempting to observe objects like Galaxy m81 and M82 the darkness of your skies not the quality of your telescope will be the biggest determinant of your success for Dark Skies you need to be far from City Lights you want Skies that are free of clouds and you want a night where the Moon is either in its early phases or not in the sky at all I recommend using a light pollution map online to help you find the darkest Skies nearest you once you're ready to move beyond the moon and planets and Beyond the night's most popular showcase targets like the Orion Nebula in Winter and the great glober cluster in Hercules in the summer most people attempt to observe the targets from the Messier list the Messier list is a 200-year-old set of objects cataloged by the French astronomer Charles Messier now several organizations including the royal Astronomical Society of Canada and the astronomical league in the USA will provide you with a certificate for observing the objects in this list if that's something you're interested in check out our book 110 things to see with a telescope each target has a customized star map and an observing log so you can record your observation and make progress toward earning your certificate well I hope you enjoy this video on observing with a refractor telescope be sure to subscribe to learn to stargaze so you don't miss the next video consider supporting us on patreon and remember the future is looking [Music] up ready ready ready go on

Channel: LearnToStargaze

Views: 2,084

Keywords:

Id: eFyZGw3fo94

Length: 11min 11sec (671 seconds)

Published: Thu Jun 06 2024