The stereo eyepieces are dark, nothing to see. The trinocular eyepiece upwards give light. What shall I do to see the specimen in the stereo eyepieces? (I know only a little of english language,) I do not understand all text in "Terms of Use" and I am not allowed to do anything that is not free. Oslo University will not pay for this.

You don't say whether this is an astronomical telescope or a terrestrial one (spotting scope). However, I have a Vivitar scope which was sold as an astronomical scope, but is actually a spotting scope, although it uses astronomical style eyepieces, so...

I am not sure that it is the eyepiece you want, either. It is hard to break an eyepiece, but much easier to break the eyepiece mount or diagonal mirror fitting.

Most astronomical telescopes use a standard fitting eyepiece with a 1.25 inch outside diameter barrel. You can measure the mount where the eyepiece goes to make sure that yours is this size, then search on eBay or Amazon for "1.25 eyepiece" and you will find many available. It doesn't have to be made by Vivitar, any make will fit.

The other variable will be the focal length of the eyepiece, which is what determines it's power. The power of the scope will be the focal length of the main objective divided by the focal length of the eyepiece, so a 9mm eyepiece will give a higher magnification (and be dimmer and harder to focus and find objects) than a 20mm eyepiece. It is usual to have two or three different focal length eyepieces for viewing different objects.

Most telescopes use a standard fitting eyepiece with a 1.25 inch outside diameter barrel. You can measure the mount where the eyepiece goes to make sure that yours is this size, then search on eBay or Amazon for "1.25 eyepiece" and you will find many available. Some of these will even be made by Meade, but any make will fit.

The other variable will be the focal length of the eyepiece, which is what determines it's power. The power of the scope will be the focal length of the main objective divided by the focal length of the eyepiece, so a 9mm eyepiece will give a higher magnification (and be dimmer and harder to focus and find objects) than a 20mm eyepiece. It is usual to have two or three different focal length eyepieces for viewing different objects.

You will find a large variation in prices, which is partly due to the difference in quality and type of construction of the eyepieces. Kellner eyepieces are simple and cheap, whereas Possl or orthoscopic ones are more complex and cost more. There are reasons why people will pay more for the better eyepieces.

The power of the scope will be the focal length of the main objective (yours is 800mm) divided by the focal length of the eyepiece, so a 9mm eyepiece will give a higher magnification (and be dimmer and harder to focus and find objects) than a 20mm eyepiece. It is usual to have two or three different focal length eyepieces for viewing different objects.

Starting out, you want to use the lowest power, so the highest number, eyepiece. Do NOT use the Barlow lens if one came with the scope. Try it out during the day (but never point a telescope anywhere near the Sun). This will make it easier to find the focus point. There is a very wide range of movement in the focus mechanism, because different eyepieces focus at different points, but the actual focus range for any eyepiece will be a small part of the overall range afforded by the focusing mount.

It is unlikely that the finder scope will be much use in pointing the telescope until you adjust it to precisely line up with the main scope. Most manuals recommend that you do this in daylight, by pointing the scope at an object on the horizon and adjusting the finder to match. Once you have a tree or mountain peak in the center of the main scopes image, you can then adjust the screws around the finder scope to get the crosshairs centered on the same object. It is very difficult to do this job in the dark, especially as objects in the sky are constantly on the move.

Remember that astronomical telescopes usually show an upside down image. There is a good reason for this- erecting the image needs more bits of glass in the light path, which reduces the amount of light and increases aberrations. Even if this is only slight, astronomers prefer to avoid it, and they don't really care which way up the Moon or Jupiter appear. It is possible to fit an erecting prism or eyepiece to most astronomical telescopes, and some of them come with one.

Starting at the bottom of the Compound Microscope scope working up: The base of the scope houses the illumination system and the field lens. It also provides weighted stablility.
The field lens is where the light comes out of the base. This lens focuses the light from the bulb directly into the substage condenser.
The arm of the scope supports the rest of the scope.
Directly above the field condenser is the substage condenser. The substage condenser collects the light and condenses it further into a more concentrated beam of light. With the substage condenser you can control the amount of light and to some degree the defraction of light. This is helpful in adjusting the "contrast" in the image.
Working up, you find the "stage" which is a platform to support the specimen. The stage may or may not have a specimen holder and a set of specimen holder control knobs.
The magnifying lenses are called the objectives. They look like barrels pointing down at the stage. These are usually marked 4x, 10x, 40x, and 100x. These magnifications are further multiplied by the power of the eyepieces which are usually 10x. So, when using the 4x you are actually seeing the specimen at 40x and when you are using the 10x objective you are actually seeing the specimen at 100x and so on. The 4x is used to "scan" the specimen so that you can find the most interesting area and then focus in further on that region. It is very hard to find exactly what you want to focus in on starting with the higher magnifications. Always start with the low magnifications, 4x or 10x.
The objective lenses are mounted on a rotating turret for easy selection.
Moving on up the scope is the head. It is comprised of the eye tube and the eyepiece. If you have two eyepieces your scope is referred to as a "Binocular Compound Microscope". If you have only one eyepiece, your scope is a "Monocular Compound Microscope".

Take off any eyepieces and or any other obstructing parts and look through the tube. Do you see day light?

Then look at each eyepiece and see if you can see light through it.

The focuser and eyepiece are POINTED UP toward the sky -- the mirror is at the bottom of the tube.

Put the eyepiece with the largest number written on it into the focuser, and during the day time, practice focusing on a distant object.

The city lights will not hamper planetary viewing. Excessive power is a common mis-conception. Use 80x or so for best viewing. That would be about a 4mm eyepiece. Start with lower powers and work upwards in easy steps. The greater the power, the narrower the field of view, and it becomes very hard to find anything at all.

You don't need to get Vivitar brand eyepieces to get additional ones for your telescope. I'm not sure of the specifications for this particular telescope but in general they come in two barrel sizes for the eyepieces. The diameter of your eyepiece is probably 0.965" but could come in the more standard 1.25". You can measure the diameter and determine this quickly.

Once you know the diameter to shop for you can look for the focal length of the eyepiece you wish to purchase. They are rated such as 4mm, 10mm, 25mm, etc. The smaller numbers give you higher magnification. You can calculate the magnification by dividing the telescopes focal length by the eyepiece focal length. For example, let's say your telescope is has a focal length of 360mm and you have an eyepiece rated 10mm. Divide 360 by 10 and that gives you a magnification power of 36.

You can find eyepieces at many telescope dealers on the internet. Your selection will be far less if you use 0.965" eyepieces. You can purchase 0.965" to 1.25" adapters so that you can use the larger eyepieces with your telescope. However, on some telescopes the adapters will cause the new eyepiece to not come into focus.

You'll also find that eyepiece prices go all over the place. A good general purpose eyepiece is a type called the Plossl. The better eyepieces have more coatings too that allow more light to get through to your eye. You'll find these listed with terms like "fully multi-coated".

I hope this helps.

Good luck and clear skies!

-jodair

I am assuming by "lens" you mean eyepieces.

You don't need to get Vivitar brand eyepieces to get additional ones for your telescope. I'm not sure of the specifications for this particular telescope but in general they come in two barrel sizes for the eyepieces. The diameter of your eyepiece is probably 0.965" but could come in the more standard 1.25". You can measure the diameter and determine this quickly.

Once you know the diameter to shop for you can look for the focal length of the eyepiece you wish to purchase. They are rated such as 4mm, 10mm, 25mm, etc. The smaller numbers give you higher magnification. You can calculate the magnification by dividing the telescopes focal length by the eyepiece focal length. For example, let's say your telescope is has a focal length of 360mm and you have an eyepiece rated 10mm. Divide 360 by 10 and that gives you a magnification power of 36.

You can find eyepieces at many telescope dealers on the internet. Your selection will be far less if you use 0.965" eyepieces. You can purchase 0.965" to 1.25" adapters so that you can use the larger eyepieces with your telescope. However, on some telescopes the adapters will cause the new eyepiece to not come into focus.

You'll also find that eyepiece prices go all over the place. A good general purpose eyepiece is a type called the Plossl. The better eyepieces have more coatings too that allow more light to get through to your eye. You'll find these listed with terms like "fully multi-coated".

I hope this helps.

Good luck and clear skies!

-jodair

You don't need to get Vivitar brand eyepieces to get replacement ones for your telescope. I'm not sure of the specifications for this particular telescope but in general they come in two barrel sizes for the eyepieces. The diameter of your eyepiece is probably 0.965" but could come in the more standard 1.25". You can measure the diameter and determine this quickly.

Once you know the diameter to shop for you can look for the focal length of the eyepiece you wish to purchase. They are rated such as 4mm, 10mm, 25mm, etc. The smaller numbers give you higher magnification. You can calculate the magnification by dividing the telescopes focal length by the eyepiece focal length. For example, let's say your telescope is has a focal length of 360mm and you have an eyepiece rated 10mm. Divide 360 by 10 and that gives you a magnification power of 36.

You can find eyepieces at many telescope dealers on the internet. Your selection will be far less if you use 0.965" eyepieces. You can purchase 0.965" to 1.25" adapters so that you can use the larger eyepieces with your telescope. However, on some telescopes the adapters will cause the new eyepiece to not come into focus.

You'll also find that eyepiece prices go all over the place. A good general purpose eyepiece is a type called the Plossl. The better eyepieces have more coatings too that allow more light to get through to your eye. You'll find these listed with terms like "fully multi-coated".

I hope this helps.

Good luck and clear skies!

-jodair