Exit pupil distance and focusing method of the telescope

1. Exit pupil distance of the telescope

When designing the telescopic system, it is necessary to provide comfortable viewing conditions for the eyes. The distance between the exit pupil and the last side of the eyepiece should be considered, called the lens distance. When using a telescope, the pupil should be in the position of the outgoing pupil. In order not to collide with the eyelashes, the lens distance should not be less than 5mm. If the telescope is used under vibration conditions, the scope must be enlarged. The lens distance of a military telescope should not be less than 16mm. A longer lens distance is required for a telescope with a gas mask.

A telescope shot of nature

2. Focusing method of the telescope

(1) Install eye cup: rubber visor can prevent stray light from escaping into the observation effect; please remove or fold glasses back if you want to wear glasses. Adjust the rubber eyecup and fold the eyecup when wearing glasses. No glasses, glasses up. Rotate and slide the rubber eyecup, while wearing glasses, turn the eyecup clockwise to the fully retracted position. Without glasses, turn the eyeglass counterclockwise to the fully elongated position. Once the rubber eyecup is set up, you will have a clear and complete view of the telescope from the right spot, with or without glasses.

(2) Adjust pupil distance: clamp elbows and hand walls of both hands to the chest to form a support point for stable observation; Remember to keep your hands and arms open. The two eyes are adjusted according to each person. Only when the two images are combined into one can the stereoscopic effect of binoculars be played. If the pupil distance is not properly adjusted, the image you see may be uncomfortable. When you see two images of an object, carefully open or close the binoculars. When the two images are merged into one, forming a perfect circle, stop turning the mirror.

A telescope shot of nature

(3) Diopter adjustment (central binoculars): the elbows of both hands, hand wall clamped to the chest to form a support point for stable observation; Use the middle finger of your right hand to push the center focus wheel until it is clear. The right eyepiece of some binoculars can also be used for precise focusing, so users are required to rotate the central focusing wheel to make the left eye clear, and then close the left eye and use the right eye to compensate for more precise focusing, so that the right eye can be as clear as possible.

The sequence is as follows:

1) First observe the distant object through the left eyepiece with the left eye, and adjust the central focusing ring to adjust the focal length.

2) Then observe the same object with the right eye through the right eyepiece, and adjust the focal length by rotating the diopter adjustment ring. When adjusting the diopter of a zoom telescope, first set the magnification to the maximum. The adjustment of the diopter will make it easy for users with poor eyesight.

(4) Focusing: from now on, when observing objects at different distances, as long as you adjust the focusing ring, you can align the focal length, and there is no need to adjust the focal length of the left and right eyepieces. Never use binoculars to look at the sun or you will hurt your eyes.

The vast sky

3. Safe use of telescopes

On the export packaging, it is required to indicate “not used to observe the sun” to prevent eye damage. Most people, including many telescope enthusiasts, do not understand the problem: the telescope should not be exposed to sunlight, because the telescope has the effect of concentrating light, as the sun’s position changes, once the objective lens is directly in the direction of the sun, the hot spot may damage the eyepiece, or even cause a fire. This is especially important for desktop telescopes. That is, try not to put the telescope in direct sunlight.

4. There are two special cases of telescope use.

(1) At the time of use, the camera is not recommended through the common glass Windows, because ordinary window glass, the surface is not smooth, in some places thicker, some places thinner, and the quality of a glass material is also uneven. If you are interested, you can compare them, through the ordinary observation scene can be seen on window glass and the effect will be discounted. Only by opening the window can you enjoy the good effects of the telescope.

A telescope shot of nature

(2) In winter, in a warm room, open the window to observe, it will also find that the effect is still down a lot, not clear, even a clear, fuzzy. This is also an interesting phenomenon because the temperature difference between indoor and outdoor is quite large in winter, so there will be strong airflow near the window, because the density of the air in this place is very uneven, so it will affect the light, and because of the magnification of the telescope, these things will be amplified and observed. In winter, using binoculars outdoors, none of this happens.

These two situations can also be experienced with hand-held telescopes, but for high-power desktops (tripod) viewing telescopes, as well as astronomical products, will be particularly obvious.

5. Telescope storage

If the telescope is not used for a long time, it is recommended to put it in a dry, ventilated, and cool place. Especially in the south, the climate is humid. This applies to the storage of all-optical instruments, including microscopes, camera lenses, etc.

As precision optical instruments, telescopes should be avoided as much as possible from bumping and squeezing. Telescopes are carefully tuned before they leave the factory. Including military telescopes, all need to be well protected. Once the accuracy is damaged by collision and extrusion, it is necessary to return to the manufacturer to check the instrument again.

natural scenery

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