Question about Tasco Specialty 301051N (100 x 50mm) Telescope

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The Barlow lens goes between the diagonal and an eyepiece. It doubles (2x) the magnification of the eyepiece used.It does this by halving the f/ ratio of the scope.

Eyepiece alone gives 35x; barlow with eyepiece =70x.

Note: this scope comes with an erecting eyepiece and is NOT suitable for atronomy use (other than perhaps the moon)

Posted on Mar 19, 2011

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Posted on Jan 02, 2017

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You stick in the same hole you look in after removing what ever was in there. Put the Barlow in there and put what ever was in there into the Barlow. Now whatever you look at will be 2 or 3 times bigger. Keep the MM of the lens you stick into the Barlow on the high side... 40-70 mm or higher... You can't break anything just try different lens.

Aug 31, 2014 | Bushnell Optics

You will have to refocus after inserting the barlow. The barlow will change the focal point of the eyepiece

Apr 06, 2013 | Optics

Can you see things in the distance during the day time? If you can nothing is wrong.

Do not use the barlow-- it is too much magnification for that size scope. Start by using the eyepiece with the largest number written on it-- center up the moon (which would make a good first target) and then exchange eyepieces. You should be able to use the 2 x barlow with the OTHER eyepiece if it is some thing like a 25mm. The barlow will make it about a 13mm.

When you use the barlow with the 9mm it makes it a 4.5mm which is too much magnification.

Do not use the barlow-- it is too much magnification for that size scope. Start by using the eyepiece with the largest number written on it-- center up the moon (which would make a good first target) and then exchange eyepieces. You should be able to use the 2 x barlow with the OTHER eyepiece if it is some thing like a 25mm. The barlow will make it about a 13mm.

When you use the barlow with the 9mm it makes it a 4.5mm which is too much magnification.

Sep 03, 2011 | Meade Optics

No the barlow increases the magnification by 3 TIMES for any eyepiece --

this will be too much for that small 76mm telescope.

Magnification is the least important quality of a telescope. Aperture and quality ioptics are much more important. I usually never use a barlow -- just the straight eyepieces in various mm sizes.

Read my tips on my profile page.

this will be too much for that small 76mm telescope.

Magnification is the least important quality of a telescope. Aperture and quality ioptics are much more important. I usually never use a barlow -- just the straight eyepieces in various mm sizes.

Read my tips on my profile page.

Feb 03, 2011 | Vivitar (1607225) Telescope

A Barlow lens doubles (or trebles) the magnification, but it also degrades the image. You are better off without it. People tend to buy telescopes on their magnification figures, even though these are essentially meaningless, so junk like Barlows get added to the package to increase the advertising impact. The mere fact that one came with this telescope tells you that the quality is not wonderful.

The specification that means something in a scope is the diameter of the objective (the main lens or mirror). Magnification is just the focal length of the objective divided by the focal length of the eyepiece. You can usually see more at lower magnifications, as the resolving power of the objective is often less than the advertised magnification. A smaller distinct image is better than a big blob of fuzz. That's why you were advised to try the scope first with the larger number (lesser magnification) eyepiece.

But try out the Barlow and see for yourself.

The specification that means something in a scope is the diameter of the objective (the main lens or mirror). Magnification is just the focal length of the objective divided by the focal length of the eyepiece. You can usually see more at lower magnifications, as the resolving power of the objective is often less than the advertised magnification. A smaller distinct image is better than a big blob of fuzz. That's why you were advised to try the scope first with the larger number (lesser magnification) eyepiece.

But try out the Barlow and see for yourself.

Nov 19, 2010 | Bushnell Voyager 78-9470 (470 x 60mm)...

They multiply the magnification of the eyepieces. Insert the barlow first and then insert the eyepiece into the barlow.

SO--- let's use the 2x as an example. If you have a 20mm eyepiece, then with the 2x barlow it becomes a 10mm eyepiece.

SO--- let's use the 2x as an example. If you have a 20mm eyepiece, then with the 2x barlow it becomes a 10mm eyepiece.

Aug 24, 2010 | Tasco Galaxsee 45-060675 Telescope

There is no such thing as a 3x barlow telescope. A barlow is a small accessory that multiplies the magnification of any eyepiece.

This is a barlow-

http://www.agenaastro.com/GSO-1-25-2x-Barlow-Lens-p/obar-gs-gs2bl.htm

This is a barlow-

http://www.agenaastro.com/GSO-1-25-2x-Barlow-Lens-p/obar-gs-gs2bl.htm

May 19, 2010 | Optics

The barlow is inserted into the diagonal and then the eyepiece is inserted into the barlow.

Try this during the day and practice focusing oin a distant object. I think you will discover that using the barlow gives to much magnification, and makes focusing very difficult.

Put the eyepiece with the largest number written on it into the diagonal WITHOUT using the barlow and note how much easier it is to focus.

The maximum magnification for any telescope is 50 times aperture. So a 4 inch scope is 200 power. Usually you will never be able to get 50 times but only 30-40 times due to turbulence in the atmosphere.

Try this during the day and practice focusing oin a distant object. I think you will discover that using the barlow gives to much magnification, and makes focusing very difficult.

Put the eyepiece with the largest number written on it into the diagonal WITHOUT using the barlow and note how much easier it is to focus.

The maximum magnification for any telescope is 50 times aperture. So a 4 inch scope is 200 power. Usually you will never be able to get 50 times but only 30-40 times due to turbulence in the atmosphere.

Nov 30, 2009 | Optics

You mean your 2x or 3x barlow. These can be purchased from many on-line retailers:

Here are two:

http://www.telescope.com/control/category/~category_id=barlows

http://www.agenaastro.com/Barlow-Lens-1-25-inch-s/66.htm

Here are two:

http://www.telescope.com/control/category/~category_id=barlows

http://www.agenaastro.com/Barlow-Lens-1-25-inch-s/66.htm

Nov 07, 2009 | Tasco Galaxsee 46114500 (500 x 114mm)...

I use a barlow lens quite a bit with my telescope. It is usually inserted before the diagonal if you use one or before the eyepiece if you don't. The barlow lens for your telescope will double the power of the eyepiece used.

However, despite what the manufacturer claims for your telescope things will look quite poorly if you try to view at 180 power. Generally you'll get the best images by using 50x for each inch of your objective lens. For example, your telescope has a 50mm lens. That's roughly 2 inches. 2 inches times 50x gives you a maximum useful power of 100x. Depending on the viewing conditions you may be able to exceed this or not even reach it. Things will look blurry and dim when you try to use too much power.

Your power or magnification is calculated by dividing your telescope focal length which is 360 mm by the eyepiece focal length. You have two eyepieces with focal lengths of 4mm and 20mm. If we divide 360mm by 20mm we get 18 power. If you add a barlow to that you get 36 power. Dividing 360mm by 4mm (no barlow) we get 90 power. That would be your maximum useful power.

Therefore, you should be able to used the 20mm eyepiece with or without the barlow but the 4mm should only be used without the barlow.

I hope all of the math wasn't confusing.

-jodair

However, despite what the manufacturer claims for your telescope things will look quite poorly if you try to view at 180 power. Generally you'll get the best images by using 50x for each inch of your objective lens. For example, your telescope has a 50mm lens. That's roughly 2 inches. 2 inches times 50x gives you a maximum useful power of 100x. Depending on the viewing conditions you may be able to exceed this or not even reach it. Things will look blurry and dim when you try to use too much power.

Your power or magnification is calculated by dividing your telescope focal length which is 360 mm by the eyepiece focal length. You have two eyepieces with focal lengths of 4mm and 20mm. If we divide 360mm by 20mm we get 18 power. If you add a barlow to that you get 36 power. Dividing 360mm by 4mm (no barlow) we get 90 power. That would be your maximum useful power.

Therefore, you should be able to used the 20mm eyepiece with or without the barlow but the 4mm should only be used without the barlow.

I hope all of the math wasn't confusing.

-jodair

Feb 12, 2009 | Edu-Science (10166) Telescope

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