Hi and welcome to eyes on the sky my name is David fuller and I try to make
it easier to understand the science of astronomy in this video I'll be
discussing how to set up and align a telescope on an equatorial mount
sometimes known as a German equatorial mount now for the newcomer there can be
a myriad of knobs and clutches and angles that don't seem to make a lot of
sense but hopefully by the end of this video you'll be able to set up and align
your mount with ease so let's begin in this video we'll cover the following
latitude leveling and balancing alignment and starting point the
celestial pole and polar alignment first take your telescope off of your mount
we'll be doing some adjustments to the mount and this will help avoid any
accidents that could damage your scope do a quick internet search of where you
live or a large city or town within a hundred miles or so and find your
approximate latitude find the latitude scale on your mount which may look like
this or this and then after unlocking the clutch set the pointer on the
latitude scale to the latitude at or near the latitude of where you live
relock the latitude adjustment it doesn't have to be perfect for right now
within a few degrees is fine
next is leveling the tripod and mount a good way to avoid accidental tip overs
with your equatorial mount is to make sure that the entire assembly is level
on the ground if your mount doesn't have a bubble level on the mount like this
you can tape a large coin to a piece of string and hold it directly underneath
the center of your telescope if the coin hangs right over the middle of the
eyepiece tray then it's level
the next step is often misunderstood but it's very important and that is
balancing your scope there are two axes to an equatorial mount but let's start
with the right ascension axis very often there are setting circles on the right
ascension taxes and it's likely the larger of the setting circles like this
or this this is the axis that has the telescope on one side and a
counterweight on the other begin by setting up your telescope similar to how
you'd be using it at night so start by placing your telescope back onto the
mount and put a low power eyepiece in the focuser these will often have a 20
25 or 26 printed on them somewhere like these now unlock the right ascension
clutch and rotate the mount so that your telescope is off to one side like this
holding the telescope with one hand and leaving the clutch unlocked release the
set screw on the counterweight and slide the counterweight back and forth on the
counterweight shaft until you can feel that the telescope tube
neither drops nor rotates back up it should be well balanced
you
unlock this clutch and turn the telescope most mounts will have the
telescope tube in some kind of rings or cradle loosen the cradle or ring locks
just enough that the tube can slide back and forth this axis is a bit harder to
get balanced well especially with lighter tubes but if you sort of set the
scope sideways then push it back and forth you can get an idea of which side
may still be heavy like this adjust as necessary when you're satisfied that the
telescope tube is well balanced in this axis point the telescope so that it is
straight up over the equatorial mount then relock the clutch now your scope is
in the starting position I know I know all that just to get to the starting
position
it helps to understand why an equatorial mount was developed
recall that the earth spins on its axis making one rotation in 24 hours well as
the Earth spins the objects in the sky appear to move across the sky but in
reality they're not moving it's us that are the ones that are spinning look at
this video of a sped up representation of the night sky all that is due to the
earth spinning not the stars themselves spinning over us so because we're
spinning we want to be able to point a telescope at a given object in the sky
say the moon or Jupiter or even another galaxy and keep that object centered in
the eyepiece without it drifting out of the field of view that's what an
equatorial mount does and with a motor drive or slow motion control it keeps
the night sky object stationary in the eyepiece so how do we set up our
equatorial mount to counteract the spinning of the earth on its axis so
that objects don't drift out of the field of view in our eyepiece
by aligning our latitude adjusted levelled and counterbalance telescope at
the celestial Pole
the celestial pole is simply an imaginary spot in the sky around which
all the other objects in the sky appear to rotate let's go back to that video of
the stars rotating note how there's a bright star very close to the center of
the video that we saw for those of us in the northern hemisphere we align our
equatorial mounts towards that star which is Polaris or the North Star
so the telescope rotates slowly on the right ascension axis opposite the
direction from the Earth's rotation since that axis will be parallel to the
Earth's axis by being aligned with Polaris thereby counteracting the
Earth's rotation so how do we align at Polaris first begin with your telescope
tube in the starting position on the equatorial mount as we discussed earlier
next make sure that the tube is aligned with the right ascension axis and the
declination axis so that everything is parallel and square
now whatever tripod leg is closest to pointing to the south
set it so that it is sitting due south you may even need to re-level your
tripod and if that is necessary after moving do that now your telescope may or
may not be pointing north anymore but that's okay
unlock the azimuth lock and turn the entire mount and telescope assembly
without turning the tripod so that it is facing due north like this crouched down
behind your telescope tube and looking up over the top of it you can eyeball
how close you are to Polaris and since it's daytime while we're shooting this
video we need to stand in for Polaris of course when you move down alongside of
the telescope tube Polaris may still be too low or too high so remember how you
pointed that one telescope leg to the south unlock it and push the scope
tripod mount assembly up or down until you have Polaris more closely aligned
now unlock the latitude adjustment and if you have one use the fine
adjustment to eyeball the tube closer to Polaris if you don't have a fine
adjustment neck and mechanism be careful and have someone help you with this part
looking through your finder scope see if you can locate Polaris if so great
you're very close to polar alignment continue using the fine equatorial
adjustment and azimuth adjustment until Polaris is centered in your finder scope
crosshairs when Polaris is centered in your finder
scope look through the low power eyepiece in the focuser of your main
telescope tube is Polaris there if your finder scope is aligned properly it
should at least be visible through the main telescope continue making fine
adjustments until Polaris is centered in this eyepiece okay so now you found
Polaris and aligned your scope lock the azimuth and latitude locks and drumroll
please now your polar aligned so let's quickly review set the latitude
adjustment on your telescope mount to the latitude of your location get the
mount and tripod close to level balance the mount by adjusting the counterweight
and by sliding the tube in the cradle or rings align the tripod assembly and
place the scope in a starting position find the celestial Pole find Polaris in
the finder scope and adjust until Polaris is centered in the main scope
and that's pretty much it now if you are able to take your
telescope intact and bring it inside then you're all set because what you can
do is actually bring the telescope back outside and put it in the exact same
location to be able to observe on subsequent observing sessions however if
this is not possible what you can do is at least be able to set up the telescope
more quickly when you do a polar alignment and besides you won't have to
do certain things a second time such as the latitude adjustment if you
have any other astronomy questions please feel free to visit me at eyes on
the sky.com we have all kinds of free star charts information on how to find
things in the night sky as well as ways to be a more frugal astronomer while
enjoying the night sky more I'm David fuller keep your eyes on the sky you
never know what you might see