What is a barlow lens do on a telescope?

Question

also what would a 60mm refracting telescope let me see?

Answer 1

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.

Answer 2

A barlow lens basically doubles the magnification provided by an eyepiece while keeping the field of view the same. They are technically "focal length increasers"

You see the magnification that an eyepiece will provide in a telescope is calculated by, magnification = (telescope focal length)/(eyepiece focal length)

If I had a telescope with a focal length of 1219mm and popped an eyepiece in with a focal length of 25mm, my magnification would be 48.76x

If I wanted to get a higher magnification, say twice that, one way I could do it is to use an eyepiece with a shorter focal length, such as a 12.5mm eyepiece. The thing is, the shorter the focal length of the eyepiece, the less eyerelief they have and typically, the smaller the hole to look through is, and the narrower the field of view they have, making for very uncomfortable viewing.

The equation above shows me that instead of changing the eyepiece, to get twice the previous magnification, I can increase the focal length of the telescope. This is what a barlow lens does. There are 2x, 3x, and 4x barlows but 2x is the most common.

A 60mm refractor will generally let you see what a waste of money it is. You'd be far better off buying some good 7x50 binoculars. These will collect only slightly less light than the 60mm refractor, will very likely have far better optics, and allow you to use both eyes which really helps.

To just start to see the types of things you should see in a telescope, you don't want anything smaller than a telescope with 4.5" of aperture...this is the diameter of the primary mirror or lens. This will most likely be a reflector though, so mirror.

The more aperture a telescope has, the more light it collects, and the more you will be able to see. 8" is a really good size for a telescope. They are fairly affordable, allow you to see many things, and are small enough to store and move around easily.

Answer 3

A Barlow lens magnifies the image your objective lens or mirror makes, before it reaches your eyepiece. The "apparent field" of your view is not affected, but the magnification is increased. The apparent field is the amount, in degrees, your eye sees as the size of the viewing field (not in the sky, but the size of the field). This differs from just changing lenses, because, in general, a high magnification lens has a smaller apparent field.

A 60 mm refractor of good quality will allow you to see many moon craters, the phases of venus and mercury, the rings of saturn (maybe even the Cassini Division), the major moons of Jupiter, perhaps a belt or two of the atmosphere of Jupiter and the Red Spot, many nebulas, the Andromeda and other bright galaxies. It is a good first telescope, if (again) of good quality. Don't be fooled by claims of "400x Magnification". A 60 mm refractor (about 2.4 inches or so) has an upper limit of 120 X useful magnification. Useful magnification is the magnification up to which more detail can be seen. More than that you are just magnifying atmospheric distortion and imperfections in your scope. The same "50 X per inch" applies to reflecting telescopes, as well.

By the way: if your telescope comes with a solar filter that screws on the eyepiece, throw that filter away, unless you want seriously to risk your eyesight. Get one that attaches to the other end of the telescope--they filter the sun before it gets into the telescope itself and are (almost) perfectly safe. Or, get an attachment to project the sun's image onto a surface through the eyepiece (very safe, indeed). If you decide to get a Cassegrain telescope, instead, don't use the projection method..you can crack your main mirror because the heat is trapped inside the tube..use one that attaches to the end away from the eyepiece.

Answer 4

A barlow lens multiplies the magnification by the amount of times written on the barlow lens.

Answer 5

maximum barlows slide into the focuser tube and you insert the eyepiece interior the barlow, yet there are different configurations. interior the barlow, insert the backside powered eyepiece you have. Then slowly turn the focusing knobs till the image is sharp. Barlows in actuality boost the magnification so customarily you will desire to zoom out to concentration.