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How to a Use Dobsonian Reflector Telescope


New Astronomers, Michael here and thank you
for tuning in to my channel. And in this episode, I’m gonna be going over the basics of using a dobsonian telescope. First of all, the instructions in this video is aimed at
new astronomers Looking for some help just to get started Or to returning astronomers who may have forgotten
how to use dobsonian telescopes. And if you’re of the latter, I think this
is a good refresher video. Secondly, the instructions in this video pertains to telescopes without
go-to mounts Meaning that there is no computer that will
automatically slew the telescope to objects in the sky. This is only for basic mounts that are not
motorized. A dobsonian telescope is a newtonian or a
reflector telescope Using an altazimuth mount called a dobsonian. This was named after John Dobson who is credited
for popularizing the use of this style of mount allowing for larger, compact and more affordable
telescopes. This style of mount uses the same 2-axis mount Having the horizontal or azimuth axis And vertical or altitude axis. Many consumer grade mounts use this same principle
of a mount At the opposite end of the spectrum, the largest optical-infrared observatory,
the VLT, also uses telescopes mounted on altazimuth
mounts. So I’d say you’re in pretty good company. And so without further adieu, Here are the steps for using a dobsonian telescope Starting with step one, which is to inspect
and assemble the telescope. This tube here is called the optical tube
assembly Which is made up of several components. Check your OTA for any missing or broken parts
including: The primary mirror: which is located at the
bottom of the tube. The secondary mirror: which is the smaller
mirror mounted near the top of the OTA. The finderscope. The focuser tube. The base: make sure that it can swivel. The control knobs: make sure that they can
turn and that they can lock the vertical axis. And your eyepieces. Step 2: Collimate the telescope Collimation is the process of adjusting the primary and the secondary mirror Using these knobs here or what not. However, some telescopes have fixed primary
and secondary mirrors. So you can throw them in the back of your
car for transport And the mirrors will stay in place. However, if your telescope is like this one
and it’s sensitive to bumps you may have to collimate the telescope frequently
or before each use. I’m not gonna cover the process of collimation
in this video But I did make a detailed video about it in
a previous episode. So I’m just gonna create a link in the description
or If this video supports it, I’ll add a hotlink right here. So just click this, watch the video and come back. Step 3: Align Your Finderscope Your finderscope gives you a low magnification
view of the sky so that you can slew your telescope in the
general direction of the object that you would like to observe. If it is properly aligned, you should be able
to see that same object in your eyepiece. However, because the finder scope is independently
mounted, It could can get knocked out of alignment
during transport. The basics of aligning your finderscope is to first locate a distant object like a
light post, And center that image in your lowest powered
eyepiece’s field of view. Then lock down your telescope, And look through your finderscope and center
that same object Using the adjustment knobs on the finderscope’s
mount. I’ve actually made a detailed video of how
to align your finderscope So if you would like to watch that please Click right here or I will also add a link in the description. Step 4: Observe through the finderscope But first, make sure that the base is as level
as possible. This is important because the horizontal axis
will usually not have a locking mechanism. So if for example if you were to situate
it in a slight tilt, like in a slope, The heaviest part of the telescope is going
to tilt towards the bottom of that slope. Next, don’t forget to remove the dust caps
from the OTA and the finderscope. I’m sorry to state the obvious but some
of you might skip this step Because it’s so obvious But if you’re at a dark sky site These dust caps are dark and they’re kind
of difficult to see Or if you’re like somebody I know Who owns a collapsible dobsonian for the first time observing Probably didn’t realize that the bottom
one also has a dust cap. Next, aim or “slew” the telescope in the
general direction of the object that you want to observe. Rotate telescope about its base horizontally then loosen the adjustment knobs Then tilt the telescope up or down about its
altitude axis. Looking through your finderscope to locate
the object And then lock it down. Remember that your finderscope is gonna have
a slightly greater magnification So the distances between stars will be a little
bit greater. Also, if you have a right-angle finderscope, the images might be upside-down. This particular one has a prism that automatically
corrects them so that they appear right-side up As if you are looking through a straight-through
finderscope. Step 5 is to observe using your lowest-powered
eyepiece And by power, I mean magnification. Take a look at your eyepieces. If there is an X beside them Then, choose the one with the lowest number. If not, they are probably in millimeters like
the ones I have here In that case, choose the one with the highest
number In this case it’s gonna be 24 Take that eyepiece and insert it into the
focuser tube. And lock it down. Then turn the focuser knob to sharpen the
image. If you wear glasses like me, Then you might find that you can’t reach
focus because your eye is too far away from the surface. If your eyepiece has a rubber shield around
it like this, You can fold it away to get closer to the
eyepiece. And if your finderscope aligned, You’re gonna see the same object in the
eyepiece. Enjoy! If you’re just starting out, I recommend that you first practice observing
bigger and brighter objects like the moon. And also, keep in mind that the earth rotates so this causes objects in the field of view
to drift away and using a high magnification eyepiece will make objects drift away quicker. So I also recommend that you first use low
magnification eyepieces So that way, you can observe longer by making
fewer slew adjustments. Well, that about does it for this episode, If you have any questions or concerns, Please let me know in the comments section. And also I’d like to point out that the
methods and procedures that I gave you in this video Are just the way I like to do things. If you have your own ways and if you have tips and tricks, please let us know in the comments section
as well. I hope that this video was helpful to you
and if it was, please hit that like button, or better yet, hit that subscribe button, and I’ll see
you in the next video. As always, clear skies, and thanks for watching.

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Comments
  • I have a 6×30 optical finderscope (also from Skywatcher) , and because it only has 2 screws it is very hard for me to align it to the main tube, any hint about that?
    It is this one : https://www.alphacygni.com/6411-thickbox_default/buscador-skywatcher-recto-6×30-con-soporte-blanco.jpg

  • I was going to comment on this last night and got side tracked. We need more videos like this so beginners can see the working ends of how a telescope like this works. Great Video and very informative. Astronomy is the most amazing thing and with today's technology and the more advanced scopes with larger mirror cells or glass; the heavens are limitless.

  • Thanks for your video. I'm thinking to buy a telescope like yours, and I'm intricate about the black piece between the two OTA pieces. What material is it and how you put it. Thank you very much!

  • Sir excellent explanation. I did not even consider that observatories use the same type of Mount but only larger. I'm thinking about it now the Dome swivels left and right and the telescope goes up and down. Wow the lightbulb just went off in my head.

  • Thanks for your videos, very useful for the beginner astronomer that I am! Little question, I'm going to get the same telescope as you, and I'd be interested to know where did you buy the protective fabric that's in your telescope? which brand is it? Thank you again and sorry for my poor english …

  • Thank you very much for this video! I’m just starting out with a (smaller) Dobsonian. I appreciate the time you took to help out us “newbies”.

  • Hi
    I am a newbie of telescope. Originally i ordered the Orion 9826 StarMax 127mm Equatorial Maksutov-Cassegrain Telescope but after i do some research it seems Orion SkyQuest XT8 PLUS Dobsonian Reflector Telescope is more powerful and can last longer …am i make a right choice?

  • i would love one of these big dobs – i live in the nyc and have a small back yard — i have a Meade LightBridge Mini – 130mm – i love it but the planetary views are small. how does is the planetary views from a 10" Dob? i would love a "goto" one because i can't starhop if there are hardly any.

  • Я думал на такой телескоп, можно загорающих голых женщин разглядывать, на планетах других галактик.

  • Can you please tell me if you added at Zenith mirror that is 1.25" in size (the diagonal prism mirror)? I want to add one on so the images are right way up.

  • Very informative. Please make review video of this telescope. How is visual Observation with it from city as well as from dark sky. Details about the objects that can be seen with description of Observations. It will really help in making decisions. Please do share your experience with this telescope in the form of pros and cons.

  • Thanks for the videos. I just bought a xt8i orion. I'm trying to find the best lenses for it. What do you recommend? Also where do I buy a replacement Spherical Mirror/primary mirror?

  • Im looking to get the 10" synscan goto. Is it worth it and whats your opinion on that? Are things like neblula even visible with something like that?

  • Hi! I just got my new Dobsonian 8” Skywatcher telescope, and after assembly I find that the swivel moment on the base is very stiff, and seems like there is too much friction. I have assembled it exactly as the instructions and countless of YouTube videos say, but can’t figure out why it’s so hard to swivel! Please help!

  • I cant seem to get a clear image to save my life. Off the bat, its collumated and the mirrors look to be in good shape. At most i can get blurry images with the 30mm eye piece…. any and i mean any focusing will result in a large white out with a black dot and lines coming out of it. Looking through the 9mm is worse because off the bat with no focusing the image is a white out with black dot and lines coming out of it. Am i doing something wrong? I am using the eye pieces it came with… do i need better eye pieces.. i'm totally confused as to why i cant get a single clear image

  • Thank you man. Just got a amazing gift from my dad, a 8" Dobsonian.
    I had idea how to properly work it until now.

  • Pleased to see that you pointed out it is A Newtonian reflector invented by Sir Issac Newton about 400 years ago, sitting on a basic alt/az mount attributed to John Dobson 400 plus years later. So many newcomers are under the impression that John Dobson invented this optical system. Always nice to help get accurate information out their. Good viewing. 🔭🇦🇺

  • Hi, thanks for the nice video. Your telescope seems to be a closed model: is it a piece of black tissue that is provided to look like a solid closed tube ?

  • i'm having hard time tracking saturn on my rented 8" skywatcher using high mag 10mm with barlow (dont want to go lower)> Maybe you have tip?

  • for imaging sure
    but for visual observing i see no point in having go-to do the work for you. Finding your way in the sky is half the fun.

    btw very large telescopes are on altaz mounts exclusively because of sheer size. Field derotators are used then for long exposure imaging.

  • Thank you for your informative videos!!
    I recently bought myself a Skywatcher Flextube 200p – 8" Dobsonian with the Synscan. Got it for a great price on sale $699.
    I have a question about collumating it…if you can help me . I have a good laser collumator and it definitely shows off target.. . it's in need of collumation….. So I'm looking at the Rear of the OTA and there are only three small Phillip's head screws which are very tight…..they appear to be holding on the outer trim ring of the OTA rather than for collumation.
    How do I collumate the Primary mirror on the OTA then ?? Did Skywatcher somehow seal the parabolic Primary mirror requiring collumation at the secondary mirror only??? I DON'T want to start messing with screws as I'm afraid to strip them . Any help is greatly appreciated.

  • Although this is really classic Dobson mount, it looks like it should work. the actual Dobson mount relies on Teflon bearings, a large-diameter Altitude bearing ring, and the weight&balance of the OTA to keep it from moving without having to "lock" the alt bearing. Mine needs only a slight finger pressure to slew the tube.
    It's too bad you can't add digital slewing gear to the tube, to simplify photography.

  • Very useful information for people who get back to astronomy, like me. It's very refreshing with all the steps and details.

  • Can you please recommend the best overall eyepieces for a 10" reflector F/5 dobsonian? I was interested in the Orioin Q70 eyepieces, however, I am being told these are not good for this particular telescope. Would you please shed some light on your favorites? I really appreciate your time and I enjoy your videos.

  • Thanks for the video . I think I'm about to purchase my 1st scope a dob ,10" skywatcher .. Is this a good 1st telescope? I want to see the great red spot on Jupiter and spirals on galaxys and in between the rings of Saturn,

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