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.