Stargazing Live Telescopes

Monday, 16 January 2012  |  Admin

We kept a keen eye on the telescopes mentioned in tonight’s episode of Stargazing Live hosted by Professor Brian Cox and Dara O’Brian. The BBC were of course careful not to endorse a particular brand or product but the Skywatcher Explorer 130p SupaTrak was easy to identify. This is good as it is an excellent choice for someone starting out in amateur astronomy. The program also mentioned what looked like a 3 or 4-inch achromat refractor on a German Equatorial Mount and another on a computerised GOTO mount. Of the three telescopes the Skywatcher is most capable so is the one discussed here.

Why this telescope?

The Skywatcher Explorer 130p SupaTrak is a Newtonian reflecting telescope that uses a 5-inch parabolic mirror to gather light then focus it onto another smaller mirror which reflects it out of the tube and into the eyepiece. Mirrors are easier to manufacture than lenses so are cheaper to buy in large apertures and because they ‘reflect’ light they do not suffer from the 'false colour' fringing around bright targets. All things considered Newtonian reflecting telescopes offer more performance per £ than any other design so are popular with beginners looking for a capable but affordable telescope.

What will I be able to see?

The 130p’s 5-inch (130mm) aperture will comfortably reveal a number of Jupiter’s weather bands and moons. Saturn’s ring’s will also be clearly visible and a number of it’s moons. Mars will appear as an orange disk with subtle shading. The lunar surface will show a wealth of detail and at times it will feel like you can reach out and scratch plaster! The telescope also gathers enough light to reveal a number of deep sky objects that are outside our solar system such as nebulae, globular star clusters and the brighter galaxies.

Which mount?

The Skywatcher 130p SupaTrak shown on Stargazing Live features a motorized mount that tracks the target as it moves across the sky. Motorized tracking is particularly useful if you observe with family or friends because they can take their time at the eyepiece without you intervening to re-centre the target.

The Skywacher Explorer 130p AZ GOTO takes things a step further. The AZ GOTO mount not only tracks the object, it will also find it via a computerised 'GOTO' handset. The GOTO function was mentioned in the Stargazing Live program. Essentially, after an alignment routine that includes entering your location, date and time you type in a targets name or number then at the press of a button the telescope slews across the sky then beeps when it has centred the target in the eyepiece field of view. It sounds Sci-Fi but it does work.

That is more than I want to spend.

No problem. Motorized and computer GOTO mounts are convenient but they are not necessary and they do not improve the view. The 130p is available as the Skywatcher Explorer 130p which features a more affordable manual mount. Optically it is the same and the manual mount includes slo-mo control cables for manual centring and tracking of the target. Manual tracking is not as difficult as it sounds and after some practice is something you will do instinctively, without thought.

That is still more than I want to spend.

The Skywatcher Explorer 130 and Skywatcher Explorer 130m (motorised) have the same 130mm aperture but cost less because their longer tube length permits the use of a spherical mirror which is more easy (cheaper) to manufacture. Some say parabolic mirrors are made to a higher quality but that isn’t true. Where a telescope’s tube length is long enough to permit a spherical mirror there is no benefit to having a parabolic mirror. The 130p with it's short tube benefits from a parabolic mirror, the 130 doesn't. To be fair a well-made spherical mirror in a short tube can provide very nice views (the argument for a parabolic mirror is strongest when the telescope is purchased for astrophotography). 

All the above offer the same optical quality, only the tube length and mount type vary. If you have room to store the longer tube then the more affordable 130 or 130M are an excellent choice and there is no reason to feel you have compromised.

Consider also the compact Skywatcher Heritage 130p Flextube with 130p optics on a portable quick to setup Dobsonian base.

What about collimation?

When the mirrors in a Newtonian reflecting telescope are aligned on the optical axis the light is focused precisely at the eyepiece. The mirrors will have been aligned at the factory but they might have drifted by the time the telescope reaches you. For optimum performance you will need to periodically re-align (collimate) the mirrors. Collimation is much easier to do than to explain, you need only a Cheshire collimating eyepiece. One of our customers offers this useful how to collimate a Newtonian article on her website.

Hhmm, so what else will I need?

Useful accessories include a 0.9x 1.25" Moon filter, a Planisphere and a red light torch. The telescopes are supplied with two eyepieces but at some point you will need others. Most astronomers own three or four eyepieces. We suggest you become familiar with what you have before before buying additional eyepieces but are happy to advise if you are in a hurry. You will also need a warm coat, thick socks and a hat! 

We hope this article has been useful.

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