“ALL TRUTHS ARE EASY TO UNDERSTAND ONCE THEY ARE DISCOVERED; THE POINT IS TO DISCOVER THEM.”

KNOWLEDGE BASE

Sky-Watcher Technologies

Land & Nature Viewing

Unlike astronomical telescopes, these models create an image that is both the right way up and the right way round. Most other telescopes will provide you with an upside down image. Perfect for viewing land objects and horizons.

Freedom Find

Dual encoders allow manual movement of the mount without losing alignment or GOTO capabilities.

Collapsible Tube

These model telescopes have a collapsible truss-tube design making them easier to transport. They do not require reassembly between uses.

ED Prime Glass

High quality FPL53 glass with extra low dispersion optics minimise chromatic aberration, providing higher resolution and superior contrast.

Bright Star Alignment

This is a simple method for finding your way through the stars using your GOTO hand control. Simply select a known object (e.g. Venus) and follow the prompts.

SynScan GOTO

GOTO pointing accuracy : Up to 5 arc min. Database: 25 user defined objects, Complete M, NGC and IC catalogue, partial SAO catalogues, total 42,900 objects.

WiFi Capability

The SynScan Point and Go feature simplifies the GOTO process. Simply point your mobile device to the part of the sky you want your telescope to point, press the button,and the telescope will automatically move to the location you pointed to. Download the FREE app from Google Play or Apple App Store.

Glossary of Terms

Aberration Any optical defect and/or design error which causes any of the processed light to deviate from reaching the focal point, therefore reducing the quality of the image.
Absolute Magnitude The apparent brightness a star would have if placed at a distance of 10 parsecs from the earth.
Achromatic Lens A refractor lens, made of two or sometimes three separate lenses, which has the effect of bringing most of the viewed colours to a sharp focus, thus reducing chromatic aberration.
Alt-Azimuth A simple mount that allows movement in altitude (up and down) and in azimuth (side to side).
Aperture The diameter of the primary mirror or lens.
Asterism A group of stars that appear to make an easily recognized shape, such as the “Big Dipper” or the “Coathanger”.
Astro-Photography Astro-photography is a specialised type of photography for recording images of astronomical objects and large areas of the night sky using long exposures..
Barlow Lens A barlow lens has a negative focal length which increases the effective focal length (E.F.L) of the objective lens or mirror of the telescope. It is always placed between the objective and the eyepiece and results in increased magnification and decreased field of view.
Catadioptric System A system using both lens and mirror components to produce an image, allowing these telescopes to be more compact than other designs.
Celestial Sphere An imaginary ball with the earth at its centre. All astronomical bodies, disregarding their true distance, are assigned a two-dimensional location on the surface of this ball.
Chromatic Aberration The tendency of a lens to bend light of different colours by unequal amounts. It can produce nasty haloes around bright objects. A well-made achromatic lens reduces this problem.
Collimation The process of aligning all the elements of an optical system. Collimation is routinely needed in reflectors, often in Catadioptric systems but seldom in refractors.
Declination Similar to Latitude on the Earth’s surface, it is the distance in degrees North or South of the Celestial Equator (the projection of the Earth’s Equator onto the Celestial Sphere). The degrees can be sub-divided into minutes and seconds.
Deep Sky A name given by amateur astronomers to objects beyond our Sun and its planets.
Dew Cap A tube extending forward from the front lens of a telescope. It prevents dew from forming on the lens as it cools down, and acts as a sunshade to reduce reflections during the day.
Diagonal A mirror or prism system which changes the angle and orientation of the light rays coming from the telescope to the eyepiece.
Double Star Two or more stars that appear very close in position. True double stars are in orbit about one another, while optical doubles simply seem close from our point of view.
Eclipse The blocking of one astronomical body by another as seen from the earth. The most common of these events are Solar and Lunar eclipses.
Equatorial Mount A telescope mount with an axis parallel to the axis of the earth. This provides easy tracking of sky objects and for photography when combined with a clock drive.
Eyepiece Also called an ocular. This is a small tube that contains the lenses needed to bring a telescope’s focus to a final image in the eye, much like a high power magnifying glass. Telescopes usually come with at least two eyepieces: one for low power and a second for a higher power view.
Eye Relief The distance between the eyepiece lens and the position in which the eye must be placed to see through the telescope. Telescope users who wear eyeglasses while observing, appreciate the benefits of longer eye relief.
Exit Pupil This is the diameter of the beam of light from the eyepiece which reaches the pupil of the eye. It is usually expressed in mm, and determined by dividing the diameter of the primary (in mm) by the Magnification. Knowing this value and the diameter of your dilated pupil allows you to choose the eyepieces which will work best for you with a specific telescope.
Field of View The maximum view angle of an optical instrument. The number, in degrees, supplied by the manufacturer is the Apparent Field of View. To find the True Field of View (also known as the Actual Field of View), divide the Apparent Field of View by the Magnification.
Filter This is usually a disk of coloured glass or film that sits in front of the telescope eyepiece or objective. It transmits only certain wavelengths of light while rejecting others. (It is important to remember that a Solar filter must always be placed in front of the objective.)
Finderscope A low power telescope attached parallel to the main instrument which provides easy object locating and telescope aiming.
Focal Length The distance of the light path from the objective (primary lens or mirror) to the convergence of the beam. The convergent spot is called the Focus or Focal Point.
Focal Ratio This is found by dividing an optical system’s Focal Length by its Aperture. The resulting value is sometimes called the system’s “speed”.
Focuser A device which brings the light rays in a telescope to a precise focus. Common designs include geared (rack-and-pinion), gearless (Crayford-style) and helical.
Galactic Coordinates A system of latitude and longitude defined by the plane of our galaxy rather than the equatorial system (RA and DEC) based on the celestial equator. Coordinates can also be specified locally, for example by Altitude and Azimuth.
Globular Cluster A very old, large, dense cluster of stars, bound by gravity. Many form spherical clouds around galaxies. Our galaxy is surrounded by at least 130 globular clusters.
Lens A transparent optical element consisting of one or more pieces of glass. A lens has curved surfaces that bring distant light to a focus.
Lens Coating A lens coating is when an anti-reflective material such as magnesium fluoride is applied to the lens surface. Lens coatings can greatly increase light transmission and reduce internal lens flares. When all lens surfaces have been coated they are said to be fully-coated and when the surfaces are coated with multiple layers to maximise transmission, the optics are said to be multi-coated. Silicon dioxide produces a more durable coat than silicon monoxide but requires specialized equipment to apply it and is therefore more expensive. Protection is needed because, in most reflectors, the mirror is open to the elements and deterioration of the reflective layer reduces the resolution of the telescope. All Sky-Watcher reflectors are multi-coated with silicon dioxide for more durability.
Magnifying Power The amount by which a system increases the apparent size of objects. Magnification is determined by dividing the Focal Length of the telescope by the Focal Length of the eyepiece.
Objective The primary or largest element in an optical system; sometimes called the “fixed optics.”
Open Cluster A group of stars, normally resolvable, which are bound together gravitationally. They are usually about the same age, having being born together from a collapsing nebula.
Optical Tube Assembly (OTA) The housing and optical train of a telescope; not including the mount, diagonal, eyepiece or accessories.
Parabolic Mirror A parabolic or more accurately a “paraboloidal” mirror, is ground to a shape which brings all incoming light rays to a perfect focus, on axis.
Polar Axis A telescope mount’s axis that is parallel with the earth’s axis. With a drive motor, the motion of stars due to the earth’s movement can be counteracted so that they remain in the field.
Prime Focus The focal point of the objective mirror or lens.
Resolution The ability of an optical system to reveal details.
Resolving Power The ability of a telescope to separate closely positioned points.
Right Ascension Similar to but not the same as Latitude on the Earth’s surface. It is the position eastwards from the Vernal Equinox, in 24 one-hour units. The hours can be sub-divided into minutes and seconds.
Setting Circles Circular scales attached to the telescope. They are marked off in degrees of Declination and hours of Right Ascension. Together, the circles allow the position of a known object to be found by setting the dials to the equatorial coordinates.
Spherical Aberration A blurring of the image caused by the inability of a spherical mirror to focus all light from infinity to one focal point. Light rays from the edge of the spherical mirror focus to different points than those from the centre.
True Field How much sky, in angular measure, is available at the eyepiece. It is contrasted with Apparent Field, which measures the field of the eyepiece alone.
Widefield Eyepiece An eyepiece with an Apparent field of more than 50 degrees.
Zenith The point in the sky directly overhead.
WiFi Capability Control your telescope with your mobile device via the SynScan app.
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