Question about Galileo 720mm x 80mm Refractor Telescope

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It will not focus. I have used several eyepieces

It will not focus. I have used several eyepieces so either the 80 mm objective lense is defective, or the focuser is at the wrong distance.

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  • Jon Reger
    Jon Reger Jul 06, 2009

    I have used a 40 mm Plossl, a 25 mm Plossl, and a 12.5 mm Orthoscopic. All of these are quality eyepieces that work properly in my other telescopes. I did not use a barlow. Either the objective lense is defective or the focuser is in the wrong position. I can not find contact information for Galileo anywhere. At no time did I use a Barlow, nor did I mention it. What I need is the contact information for the manufacturer, not imaginary problems that do not exist.

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It sounds to me like your mirror/s need collimating. It might be worth getting in touch with your local astronomical society. They will probably have someone onboard that will have a collimator and what's more they'll show you how to use it. It would be silly to buy a piece of equipment like that for one use, on the chance that that is your problem. Most societies have a "public night" call or email them and then take it along. I have no doubt that they will be glad to help. Hope you get some satisfaction!

Posted on Aug 01, 2009

  • Jon Reger
    Jon Reger Mar 30, 2013

    It is a refractor. It doesn't have a mirror.

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You need to use that flip barlow as a spacer to reach focus

Posted on Sep 16, 2009

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Yes, I did type mirror/s I know....Your problem still could be that the lenses need collimating....just thought that I should pick up on my own mistake. Cheers.

Posted on Aug 01, 2009

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It WILL focus -- put the eyepiece with the LARGEST number in it into the tube........... DO NOT USE the 2x or 3x Barlow.......... this eyepiece is the LOWEST magnification.

Take the scope outside during the day and practice focusing on a distant object at least 100 yards away. If you are expecting 650 power forget it-- you will only get about 120 power as the maximum usable magnification, with that aperture 80mm scope.

Posted on Jun 28, 2009

  • Jon Reger
    Jon Reger Mar 30, 2013

    Wrong. You do not understand the problem. It will not focus. The focal length of the objective lens is not compatible with the focuser.

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About my tasco 46-060675 D=60mm F=900mm come with 3 eye lense 1(sr4mm) 2 (k10MM) 3(k25MM) and two tube 1(1.5x erecting eyepiece) 2 (3xbarlow lense


The different eyepieces are to give different magnifications. This is worked out by dividing the focal length of the telescope, f = 900, by that of the EP. So the 25 mm Kellner (that is the type of optics in the EP) will give 900 / 25 = 36 times magnification.

The erecting eyepiece is used for terrestrial viewing. Normally with an astro telescope everything is upside down as that does not matter when looking at a star. So when you want to look through someone's bedroom window you use this.

A Barlow lens is an add-on magnifier. If you add this onto any EP (it normally fits between the EP and the scope) it will increase magnification x 3.

There is a practical limit to what any scope will deliver, governed by its aperture (the size of the front lens) and for your scope this will be about x 120 magnification. Beyond that the image becomes too dim and fuzzy. This means that your 4 mm eyepiece ( x 225 magnification) won't be much use. It will be hard to find the object you are trying to observe, it will be hard to focus, and the image will wobble around. Nor is your barlow lens much use either I fear.

You might consider another eyepiece around 18 mm to give a nice spread. A Plossl type is good. If you get serious about astronomy, I think you will immediately want a better scope after using the Tasco.

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1 Answer

No image through lenses


1. During the daylight point the telescope towards an object (water tower, building ) something about 1/2 mile away.
2. Locate the object in your finder.
3. Use the 12.5mm lens (50x) and look through the telescope. Do not use the erect prism
4. Align the finder to what you see in the scope.
5. You can use the 4mm to fine adjust the finder.
6. On a good, clear night.Leave the scope out to reach thermal equilibrium ( about a hour) Point the finder towards the moon
7. Use the 12.5mm and then focus on the moon.

Note: This is NOT a quality scope. Avoid any scope with .965 eyepieces and silly magnifications! Max power on this scope on a PERFECT night is 200x and Huygens (H12.5) eyepieces give very narrow and poor viewing. Do not use the 3x barlow or the erecting prism. the erecting prism is for terrestrial viewing only and the barlow, although it increases the eyepiece by 3x, will also narrow the view.
Good Luck!

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1 Answer

I have a Vivitar Telescope 60x/120x VIV-50600. Once I locate the object with the scope finder and I try to view it through the bigger lens nothing is focused. I have tried using the adjuster and nothing...


The only thing I can think to ask is whether you have fitted an eyepiece (NOT the barlow lens, if it came with one). Eyepieces are small lenses marked with a focal length (in mm, like 20mm or 9mm). They fit into the part that does the focussing, and are held by a small screw that you tighten with your fingers. If you have fitted an eyepiece and it still won't focus then I don't understand what is going on.

I would suggest that this is one of those problems best sorted by an experienced person physically present.

Dec 28, 2010 | Vivitar Optics

1 Answer

We have a refractor AZ2 holder (the only name we have.) No manual, several lenes, but how to put them together??? The lenses are SR4mm, H12.5mm, 1.5X erecting eyepiece & 3X Barlow Lens. Hope you can...


The 3 x barlow will be useless for this small telescope.

Put the 1.5 x erecting PRISM into the telescope and then put the eyepiece with the largest number written on it into the erecting prism. This is your lowest magnification.

Take the scope outside during the daytime and practice focusing on a distant object. Turn the focuser knobs slowly until the object comes into sharp focus.

Aug 07, 2010 | Optics

1 Answer

?? I am having the same problem. The eyepiece I am using is 22mm?


Put the 22mm eyepiece into the focuser. The focuser end is pointed UP, the big mirror is on the bottom. Take the lens cap off, and go outside during the daytime and practice focusing on a distant object.

Sep 16, 2009 | Bushnell NorthStar 78-8846 (675 x 114mm)...

1 Answer

How do I focus on the moon. Model 1400150. I have been gifted this telescope. Tried to focus on moon. Dont know how. Took big cap off end. Looked throughscope on top of large cylinder. Tried to focus...


first, use the lowest power eyepiece, that's the one with the high number on it with 'mm' after the number.

for a refractor telescope (uses lenses), you might have to add a diagnal lens (either 45 degree or 90 degree, whichever one you have) to focus on an object.
attach it in this order:

low power eyepiece-->diagnal lens-->main telescope

for a reflector telescope (uses mirrors, a telescope with a big tube with a mirror at the bottom and a focusing knob on one side of the tube). the open part of the tube points to your target.

hope this helps :D




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1 Answer

I bought these for my husband. In trying them


Difficult to answer specifically without knowing the model. But binoculars are designed to view objects in the distance. They all have a limit as to how close they will focus based on the magnification and design. Objective lenses that are far apart such as on a porro prism binocular will not focus very close. The nature of the design of having the objectives further apart than the eyepieces doesn't allow it. When trying to focus too close the image will appear blurred and double. That is the nature of the design. 9 feet or 3 metres is considered quite close to focus a binocular and is usually for a model designed to do this such as a roof prism where the objective lens and the eye lenses are inline. A specialty binocular such as the Pentax Papilo will close focus to 50 centimeters. It has been designed so that the objective (large lenses) lenses converge.

Take into account when focusing that binoculars are also designed to compensate for differences in each eye. One of the eyepieces either right or left will adjust seperately. For binoculars with a center focus ring. First focus using the center ring with one eye covered. The eye that should be covered is the one that doesn't have the adjusting eyepiece. When the image is clear close the eye you have just used and leave the center focus alone. Focusing on the same spot look through the eyepiece that adjusts and turn the eyepiece ring until the image is clear. Now all you have to do is focus using the center ring only as the binoculars are adjusted for each eye.

Some binoculars do not have a center focus and each eye will adjust seperately.

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1 Answer

Tasco Model 59T additional lenses


Do you mean eyepieces? If so, they are either .965", 1.25" or 2". I'm betting yours are .965" or 1.25" which is a standard and you should be able to fit anyones same-sized eyepieces in the focus housing. Measure the diameter and you will know.

If you mean lenses, then the question is confusing, as you increase or decrease power by switching out eyepieces, not objective lenses.

Look on eBay for eyepieces and you'll find plenty.

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1 Answer

Can't get images


These are good scopes for the bucks.
What size eyepiece in mm do you have. What are you aiming the scope at? Try your largest eyepiece in mm at the moon.

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3 Answers

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Hello,
What you have is called a refractor-type telescope with the primary lenses (the Objective) at the top of the tube and the only other lenses in the system are your selection of eyepieces, probably a barlow lens (2X magnification of any eyepiece used), and a diagonal (in line mirror so that you cand see into the telescope from the side.). As the focal lenth of the eyepiece decreases, so does the distance away from the Objective Lens. I believe that you are using the telescope with a diagonal mirror which makes the optical path longer. The fact that your longer focal lenght eyepiece can focus and not your short one would be only if you didn't have the diagonal or the eyepiece all the way in tight to allow the focus mechanism (rack and pinioin) to get compressed enough to focus. Look at the Moon, if the image gets smaller then bigger as you focus, but not sharp, then I would have to tell you that your eyepeice lenses are not in the right order. Someoner may have taken it apart and didn.t put them back in the correct order. The lenese could just be very dirty also. Barrow a short focal lenght eyepice from a friend and see if it works in your system. Then you will know for sure.

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