Knowledge Base

BINOCULARS, SPOTTING SCOPES OR TELESCOPES?

Generally, for land usage, you would use binoculars or spotting scopes for portability and mechanical dynamics. However, as the ages have allowed the advancement of better optics and control, binoculars have extended into the sphere of astronomy.

Binoculars: Astro binoculars work in a similar way as telescopes. The difference being that Astro binoculars allow both eyes to view one object. As with the optical dynamics of the telescope, the objective lens is the most important feature as its size dictates the amount of light it allows into the binocular.  Coupled with the overall quality of the binocular, the more light it can capture, the clearer and sharper your images can be.

Measurement for Astro binoculars goes like this: MAGNIFICATION x SIZE OF OBJECTIVE LENS (in millimetres). Eg: 10x60 means a magnification of 10 and an objective lens of 60mm.

Spotting Scopes: The Spotting Scope was created specifically for land-based viewing, its optical system has been optimized just for that purpose. If you intend to primarily look at wildlife, the great outdoors and possibly a close-up of the moon, the Spotting Scope fits this need perfectly.

Telescopes: If your intention is to look at moon, planets in our solar system and deep space viewing, the telescope is perfect for that as it was made for viewing space objects specifically. Same with the binocular and spotting scope, objectives dictate the amount of light that can be captured in your telescope for viewing. Having other things to consider such as the quality of the lenses, the mirrors and overall built will give you sharper and clearer images as well.

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RIGHT SIDE UP OR UPSIDE DOWN?

When viewing through certain telescopes such as the Refractor and Cassegrain telescopes , images may appear upside down. Well upside down according to what you perceive as the norm. In fact when viewing any object in space, there is really no such thing as the correct-side up since every direction can be considered up or down.  Regardless, taking the moon for example, if you want to look at the moon as it appears with the naked eye as the ‘right side up’, then you would use something called a “Diagonal” which basically reverses what your telescope ‘sees’ as upside down. However, even with a regular diagonal, objects may still appear to be backwards left to right. To correct this, another special diagonal used called the Erect Prism Diagonal.

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TYPES OF TELESCOPE MOUNTS

Mounts are a necessity when using telescopes. It brings stability and ease of control. The usage of a mount depends on the size and weight of your telescope, current environmental condition and whether you want a manually adjusted standard mount, or with the usage of a computerized console.

There are two primary types of mounts:

Altazimuth:  The most basic type of mount which consists of the Altitude (up and down) adjustment and Azimuth (left and right) adjustment.

An updated version of this mount is called the Dobsonian mount which was created to mount large telescopes set into the ground or weighted with a heavy platform base.

Equatorial: If you ever consider astrophotography, using the Equatorial mount will allow you to adjust the mount to move alongside the Earth's axis. This is achieved using a series of knobs that allow smooth small movements.

The Equatorial mount comes in three versions: German Equatorial, Fork and Horseshoe versions.

The German Equatorial uses a counter weight to help keep the weight balance of the telescope and is often times more complicated to setup, but is good for larger longer telescopes. The Fork is simpler and allows the telescope to be mounted between two columns. The two columns are set on a base that can be rotated left and right. The Horseshoe allows your telescope to point straight upwards. This is a common mount used in ultra large telescope domes.

*Both mount types come in manual control and computerized control versions.

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USING A BARLOW LENS

The basic must-have for any beginner astronomer is the Barlow Lens. It allows you to see your telescope target with a magnification increase.  The more common ones include the 2x and 3x. 

Normally, if you use a telescope with a 1000mm focal length and a 20mm eyepiece, you would get a magnification of 50 times.  With a 3x Barlow Lens, you will get three times more of that making the magnification to 150 times. However, note that the quality of what you're seeing is still dependent on the overall combined quality of the lenses of your eyepiece and telescope, as well as the amount of light it captures.

Like telescope eyepieces, Barlow Lenses have various barrel sizes you need to take into consideration.  The two most common barrel sizes are 1.25 inches and 2.0 inches. However, make sure you check the barrel size of your eyepiece and telescope before you make your purchase.

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BASICS: USING THE TELESCOPE

In its most basic form, the three primary pieces that make up the working aspect of your telescope is the telescope itself, the detachable eyepiece and the mount in which the telescope is attached to.

Before you get your first telescope, you need to know a few things about it:

Focal Length: Measured in millimetres (mm), the Focal Length is the distance from the lens or mirror to the point of focus of the telescope.  A telescope with a longer Focal Length normally means the Angle of View is narrower and the magnification can be higher.  A telescope with a shorter Focal Length means the Angle of View is wider.

Magnification:  Also known as "Power", to calculate this, take the Focal Length of the telescope and divide it by the Focal Length of the eyepiece.  If your eyepiece has a Focal Length of 20mm and your telescope has a Focal Length of 1000mm, the Magnification is then 50 times. Take into consideration that a telescope with a high power, does not necessarily mean it is a good telescope.  A much higher magnification could possibly mean higher image degradation. You would normally use higher powers to view super far away objects such as stars.

Objective Lens:  This is the front-most lens of your telescope measured in millimetres. The larger this lens is, the more light can enter the telescope. The more light that can enter the telescope, the better the images are. Other factors come into play such as the overall quality of the glass, the lens elements inside the telescope, the mirrors that reflect the image into your eyepiece and the stability of your telescope.

Eyepiece: This is the 'portal' to which your eye can see the image your telescope captures. The eyepiece is placed closest to the Focal Point of the telescope. Eyepieces come in a very broad range of types and elements.

Mount: The mount basically holds your telescope in place. Depending on the size and weight, as well as the environmental condition, the mount will be adjusted accordingly.  It allows you to control where your telescope points to.

Ultimately, you would get a telescope that has a balance of quality between the telescope itself and the eyepiece, since neither can function without the other.