Advice 1: How to assemble the telescope

Spyglass - vintage item that allows to observe distant objects. But it is an optical device that was used in the era of Great geographical discoveries, has not lost its popularity to this day. The telescope can be done with your hands, and not just for playing or historical reenactment. This tool for ground-based observation needs to give direct, not inverted image.
How to assemble the telescope
You will need
  • — 2 lenses;
  • — heavy paper (Whatman or other);
  • epoxy or nitrocellulose adhesive;
  • — Matt black paint (e.g. enamel);
  • — wooden blank;
  • — polyethylene;
  • — Scotch;
  • — scissors, ruler, pencils, brushes.
Pick up lenses. Suitable spectacle glass that you can buy in an optical store. One of them should be from +4 to +6 diopters, the second from -18 to -21. The diameter of the positive lens is 4-5 cm, a negative 1-3 see
On a wooden cylindrical block, whose diameter is equal to the diameter of the negative lens, wrap 1 layer polietileno film and secure it with tape. You can take ordinary household package. On top of the film wrap paper tube, carefully promazyvaya each layer with glue. Pipe length shall be 126 mm. the Outer diameter equal to the diameter of the lens (positive). Remove the tube from the blank and allow to dry.
When the adhesive dries, the tube will harden - wrap it in one layer of polyethylene film and seal with tape. Exactly the same as in the previous step, wrap the tube with paper glue to wall thickness was 3-4 mm. the length of the outer pipe is also equal to 126 mm. Remove the outer part with the inner and allow to dry.
Remove polyethylene. Insert the inner tube in the outer. Less detail needs to go inside more with some friction. If there is no friction, increase the outer diameter of the smaller pipe with one or several layers of thin paper. Disconnect the pipes. Paint the inner surface black Matt paint. Dry these parts.
For the manufacture of the eyepiece glue 2 identical paper rings. This can be done on the same wooden disc. Outer diameter of rings equal to the inner diameter of the small pipe. The wall thickness is about 2 mm and a height of about 3 mm. Paint the ring black. Now made of black paper.
Assemble the eyepiece in the following sequence. The inner surface of the small pipe with one end grease glue an inch. Insert the first ring, then little lens. Put the second ring. Avoid getting glue on the lens.
While the eyepiece dries, make the lens. Make 2 paper rings. Their outer diameter should be equal to the diameter of the big lens. Take a sheet of thin cardboard. Cut out a circle with a diameter equal to the diameter of the lens. Inside the circle make a circular hole with a diameter of 2.5-3 cm. Glue the circle to the end of one of the rings. These rings are also vackraste black paint. Assemble the lens in exactly the same way as you collected the eyepiece. The only difference is that the first pipe is inserted into the ring glued to it with a circle, which should be facing the inside of the pipe. Hole plays the role of the diaphragm. Check the lens and a second ring. Let the design dry.
Insert ocular knee in the objective. Select a distant object. Move your tube to the sharp, pinching and spreading tube.
No need to make the device high magnification, otherwise the pipe will be difficult to use with it.
Useful advice
Pipe can be painted with white paint with silver or bronzovoi. Before painting, disassemble the instrument. The ocular part can be left as it is.

It is possible to equip a telescope with a lens hood for cutting off unnecessary side beams.

You can use a high quality long lens from the old camera.

Advice 2: How to choose a telescope

A telescope is an optical instrument with which is possible to observe remote objects. To choose a quality copy, you need to have an understanding of the characteristic of the pipe parameters and technical characteristics.
How to choose a telescope
Tubes for fluorescent observations have an exit pupil size of 3-4 mm, pipes of the so-called twilight vision is equipped with a pupil, whose size is in the range from 3 to 7 millimeters. No matter how persuaded you, the seller, know that a telescope provides the ability to monitor objects during dusk or in low light conditions. For observations in the night time of the day is a special night vision devices.
Choose those models, the size of the exit pupil which is as close to the size of your pupil in daylight it has a size of 2-3 mm, at night - 6-8 millimeters. To determine the size of the exit pupil, divide the objective lens diameter to increase the pipe. These indicators should be marked on its body. For example, the inscription 8x30 means that the pipe has a magnification of 8 times and the diameter of the lens is equal to 30mm.
Note his reflection in the lens of a telescope: if the production device has been used high quality ar coating, the reflection is not quite clear. The color of the coating does not matter. Check uniformly enlightened the entire surface. To do this, stand with your back to bright light and point it at the lens tube. If you shake it in different directions, you will see the image of the light source in different colors. Among them should not be white.
Think about what magnification you need for monitoring. Buying the device with the increase more than 10-12 times, get an optional tripod. Use a long glass tube with high magnification without special support will be especially difficult at night. Select several products and compare them to each other. If room size allows, watch the surroundings through the pipe. When you use tubes of poor quality, you will see colored edges around objects, blurred and fuzzy image, low contrast between light and dark objects.
Test pipe in the home. To identify defects, invisible in daylight, at night. View the stars through a telescope pipe: they must look like dots with no halos, surrounded by luminous rays. The distortion that occurs when moving pipe from center to edge, should not be large. Listen to your feelings: prolonged use of the optical device you should not encounter the fatigue and inconvenience.
But the difficulty is what to choose and how not to make a mistake in purchasing. We decided to dedicate this topic to that theme. Moreover, here we do not intend to advertise or to focus on specific models of spotting scopes or binoculars and try to consider the parameters typical of high-quality products.
Useful advice
Tips on choosing a telescope. Before you start to choose a telescope,you must first determine for what purpose you want to use and where to use the device. But if on the contrary, to see night in the daytime the telescope, then the situation changes - your eyes are accustomed to darkness, the pupil is widely expanded, he will not be able to get a full clear image due to the small diameter of the telescope.
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