Telescope Barlow Lens
What is a barlow lens do on a telescope?
also what would a 60mm refracting telescope let me see?
A Barlow lens is an additional lens that increases the magnification of an eyepiece, usually by two times, thogh there are some 2.5 and 3 x Barlow lenses.
If you have an eyepiece in your telescope that gives, say, a magnification of 75 times, then you can take out the eyepiece, put in the Barlow lens and then put the eyepiece back at the end of the Barlow and you would have a magnification of 150 times.
The idea is that you can have a wider range of magnifications without having to buy a lot of additional eyepieces. The downside to saving the money is that obviously the light is passing through more glass, so the image won’t be quite as good as if you were using an eyepiece with the equivalent magnification, though with a good Barlow most people really wouldn’t notice any difference.
As to what a 60mm refractor would let you see, that would depend on the quality of the lens, and the quality and size of the eyepiece(s). If you are asking because you are thinking of buying a telescope, then you need to think about what you want to use it for (moon and planets, or deep space objects such as double stars, nebulae and galaxies); where you will be observing from (is it a dark site or do you have a lot of light pollution); whether you want a motor drive (vital if you want to do photography) and how much you want to spend. A ‘scope of that size will generally not be very good for faint objects. The bigger the lens (or mirror for a relector), the more light that can be collected. If you can afford about £250 ($475) you should be able to get a telescope that would give you quite decent views of the Moon and the planets.
Don’t ever buy a telescope that is being touted on the basis of image magnification – especially if it says something stupid like “450x”. Magnification is the focal length of the objective divided by the focal length of the eyepice, so let’s suppose that the focal length of the objective is 800mm (the 60mm is the diameter of the lens, not its focal length). To get a magnification of 450x, you’d need a 1.7mm eyepiece, which doesn’t exist! A 25mm eyepiece is more likely, which would give a magnification of 32x, and a 15mm objective would give 53x. You’re likely to find longer focal lengths – and therefore greater magnifications – with larger telescopes.
Good luck.
|
|
Orion Observer 70mm Equatorial Refractor Telescope $129.99 Orion’s Observer 70 EQ combines the solid optical performance of a classic achromatic refractor with a German style equatorial mount. The Observer 70 features very good optics and 36 percent more light gathering power than 60mm beginner scopes. The complete accessory package includes high and low power eyepieces, a 90 degree star diagonal, a red-dot finder, illustrated instructions, and Orio… |
|
|
Orion SpaceProbe 130 EQ Reflector $229.99 The Orion SpaceProbe 130 EQ Reflector is a Newtonian reflector telescope packaged with a sturdy equatorial mount, two Explorer II eyepieces, a 6×30 finder scope, and Orionâs Starry Night Special Edition software. Invented by Sir Isaac Newton, reflector telescopes provide more light gathering power per dollar than any other telescope design. With 130mm (5.1 inches) of aperture, the SpaceProbe … |
|
|
Orion StarBlast 4.5 Astro Telescope $179.99 Orion StarBlast 4.5 Astro Reflector TelescopeLaunch a lifetime of stargazing with this compact, ready-to-use telescopeTop-notch optics show you the moon, the planets, the stars and moreScope comes fully assembled so you can go from box to backyard in minutesHigh-quality optics, point-and-view ease of use, remarkable portability, all for less than $200Your ticket to space-tourism without the zero-G… |
|
|
Celestron Accessory Kit $120.95 Celestron Accessory Kit… |
|
|
Celestron 93625 Universal 1.25-inch Camera T-Adapter $20.95 Celestron Telescope Astrophotography T-Adapter – 1-1/4in Universal 93625… |
|
|
Celestron 21024 FirstScope Telescope $27.99 In 1609, world-renowned Italian scientist, Galileo Galilei, introduced an elementary telescope to the growing astronomy community, which sparked interest into the mysterious night sky for centuries to come. Four centuries later, in celebration of the International Year of Astronomy 2009, Celestron offers the portable FirstScope Telescope. The FirstScope pays tribute to Galileo Galilei and many of … |
|
|
Using the Meade ETX: 100 Objects You Can Really See with the Mighty ETX (Patrick Moore’s Practical Astronomy Series) $20.48 The Meade ETX range of telescopes is one of the most successful ever made. It is low-cost, has sold in its tens of thousands, and is available in almost every country. Here, ETX expert Mike Weasner reveals everything any amateur astronomer ever wanted to know about the telescope. First book dedicated entirely to the ETX. Written by an acknowledged world authority. Describes the “best” 100 objects … |
|
|
On the construction of a fluid lens refracting telescope … |
|
|
BARSKA 40070 Starwatcher Compact Refractor Telescope with Table Top Tripod And Carrying Case $58.72 There’s an amazing show to be seen in the night sky and this Barska travel telescope is a great tool. You get a totally portable 300x telescope with a 70mm objective lens and a tabletop tripod. You also get a copy of the highly popular Deep Sky software, which includes a searchable database of over 10,000 celestial objects and a What’s Up Wizard that delivers a list of what is visible at the obser… |
