How to Align The Finder-Scope ?

How to Set up Your New Telescope.

(How to align the Finder Scope with the Telescope).

In the corner of the living room stands a large oblong box wrapped in gift paper. You hope it’s what you think it is. You start to unwrap it and yes it is a TELESCOPE!

Carefully, following the instructions, you assemble the Telescope. When you’re done there before you stands a thing of beauty. Taking up most of what’s left of the space in your living room.

You can’t wait for the Sun to set so you can get outside to use it. However when you point it at a star or planet you don’t see it in the Eyepiece.  It so frustrating.

You dump the Telescope in the Shed or the attic and ovet time it gets forgotten.   Yet all you needed to do was set it up correctly. Some instructions don’t tell you how to set up the Telescope.

I had a customer who had received a Telescope for Xmas. It took him two days to assemble it. He didn’t have a clue how to use it. When he pointed it at an object he couldn’t see it in the Eyepiece.

There must be lots of people who get a Telescope at Christmas or Birthday and don’t have the faintest idea how to use it. So I wrote this post to help you get the optimum Stargazing experience from your Telescope.

Before you can go outside and observe the Cosmos. The Telescope needs to be set up correctly.  It needs to be aligned with the Finder Scope.

Lets begin.

Let us assume that Your Telescope is correctly Collimated. That is The Sweet Spot of your Primary Mirror is reflected by the Secondary Mirror into the viewer, centrally, in the Eyepiece to give a perfect image.  Stars should be circular with no “coma” or “aberration”.

While it’s still daylight take the Telescope outside and place it where there are not too many obstructions.

Level the Telescope.

Most Telescopes are mounted on a Telescopic Tripod. Some are table top mounted and the bigger Newtonian type have their own rotating plinth. Whatever type you have it is essential that it is level before setting up. Some mounts have a Spirit level incorporated in the top of the adjustable legs. If not get a small Spirit level from a local hardware store. Adjust each leg until the Telescope is at a comfortable height for viewing . You don’t want to be bending over too much or you are going to get a sore back. Check that the Spirit bubble is perfectly central. The Telescope is level.

Align the Finder Scope with the Telescope.

Now the Telescope is level it’s time to align the Finder Scope with the Telescope. Use a 10 mm or 15 mm Eyepiece and Point the Telescope at a distant, stationary object as far away as possible. Something like a Chimney pot, Church spire or Telegraph pole.

Look through the Eyepiece. Don’t be alarmed! The image may appear upside down and back to front. This is normal. The secondary mirror inverts the image in the viewer. There are Image Corrector lenses that fit in the viewer to turn the image the right way up. However it’s not that important when you are observing objects Trillions of miles away.

Get the image as central as you can in the Eyepiece. The Finder Scope should already be attached to the main body of the Telescope. Switch on the Finder Scope using the dimmer switch on the side.

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Target the object in the the. Centre
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Simple Red Dot Finderscope
You might need to bend down to find the right angle to see the red light reflected on the screen of the Finder Scope. Once located Adjust the height of the light reflected on the Finder scopes lens using the vertical adjuster at the back of the Finder Scope until it is level with the object. To get the Red dot on the object use the horizontal adjuster that will move the light left or right by turning it in or out. You might need to readjust the height again until the Red dot is exactly on the object. Keep checking through the Eyepiece that image is still in the centre     ( this is called the “field of view”) and check that the Red dot is directly centred on object too.

That’s it !   The Telescope and Finder Scope are now aligned.

Fine adjustment

Fine tuning  the Telescope with Finder Scope is best done at night.

Make sure the Telescope mount is level then slew the scope so that it is pointing at a bright star. The brightest stars are Vega, Capella, Arcturus, and Sirius. These Stars are light years away so the distance is somewhat further than the object you lined the Scopes up in the day. If your not sure which Stars are what use the Star walk App or solar walk on your mobile phone or Ipad to locate one.

Once you have located a Star  i.e. Vega . Try and get it dead centre in your Eyepiece moving just the Telescope up , down , left and right until the Star is centred in the Eyepiece.

Turn on your red dot Finderscopes and adjust the brightness so that it is not so bright as to drown out the starlight. At first You will probably find that the red dot is nowhere near the Star. That’s because the distance is so much greater than object you lined up with in the daylight.

Adjust the verticals and horizontal adjusters on the Finderscopes until the Red Dot covers the Star so that you can still see the starlight around the red dot. Check in the Eyepiece agin to make sure the Star is still centred in the viewer.

Eureka!!! That should be it .

To check slew the Telescope across the sky and pick out another bright star. This time use the Red Dot Finder and line up the red dot on the Star MOVING ONLY the telescope up, down and left to right on its mount. When you’re happy that the red dot is in the centre of the Star check in the Eyepiece. The Star should be dead centre in  the Eyepiece.

Sometimes you might need some fine adjustment due to the Earth continually moving position. Unless, of course, Your Scope has auto tracking.

If so the same rules apply. Centre the object in the Eyepiece first moving just the telescope then use the adjusters on the Finderscopes to align the Red Dot on the Star.

There you have it.

I hope you found this post useful ? If so please comment and share it to help others.

Astronomy Help

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