A night vision device (NVD) is an electro-optical device that allows observation in low-light conditions. The main application of night vision devices is, of course, military, but NVDs are also used for hunting, for observing wild animals, for protecting territory, in astronomy, physics, medicine, etc. I got a Night Vision GL521 night vision device from Eyeskey for review. This NVD is based on an image intensifier tube (ITT), which amplifies light by several tens of thousands of times. That is, it is not a thermal imager, but actually an “amplifier” of the light flux.
Eyeskey Night Vision GL521
In absolute darkness, such a device will not show anything, but even a weak source of illumination (sky, stars, Moon) is enough to show what is not visible to the eye. Eyeskey GL521 is a passive night vision device – it does not have infrared illumination, as in security cameras and inexpensive NVDs based on CMOS matrices, but it perfectly sees the near infrared range (up to 1000 nanometers for sure).
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Strain wave gearing is a type of gear mechanical transmission, the peculiarity of which is the multi-link engagement. For comparison, in a conventional cylindrical involute gear the torque can be transmitted by two teeth, but wave transmission provides the load transmission by approximately half of the teeth. Another name for strain wave gearing is harmonic.
The main advantages of the strain wave gearing are reliability, compactness, high gear ratio, efficiency, service life, resistance to impact loads, as well as simplicity and maintainability of the design. With regard to astronomical mounts, one of the main advantages of using wave reducers is the refusal to use counterweights even under heavy loads. However, if the mount is heavily loaded, there is a risk of the telescope tipping over, so when using a heavy tube, it is advisable to use a counterweight. Another important advantage of the strain wave gearing is the absence of backlash (significantly increases resistance to wind) and the absence of the need for maintenance and adjustment. The disadvantages of mounts on a srain wave gearing include worse tracking accuracy than mounts on a worm gear, but when shooting with long exposures, this issue is solved by fast autoguiding (exposures of about 1 second), or software and hardware (correction of periodic error, encoders).
Sky-Watcher Wave 100i
Sky-Watcher Wave 100i is an astronomical mount, in the design of which wave reducers are used, and on two axes. Judging by the declared characteristics, a wave reducer of size 17 is used on the AZ (R.A.) axis, and a size 14 on the ALT (DEC) axis. This mount can operate in both alt-azimuth and equatorial modes. At the same time, the mount is distinguished by its small size and moderate weight (4.3 kg) for such a lifting capacity (up to 10 kg without counterweights, up to 15 kg taking into account the counterweight). The manufacturer recommends not to overload the mount and to avoid breakages, the weight of the entire observation structure, INCLUDING THE COUNTERWEIGHT, should not exceed the maximum permissible load on the mount.
Another interesting feature of the Sky-Watcher Wave 100i mount is the ability to place two tubes simultaneously on different sides of the mount (instead of the counterweight axis). Not only the mount head arrived for review, but also an extension column, a tripod, a counterweight with an axis (not included in the kit, purchased separately).
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Sky-Watcher BK 705AZ3 is a compact lens telescope with a 70 mm objective diameter and a focal length of 500 mm. The telescope is supplied with a Sky-Watcher AZ3 alt-azimuth mount with micrometer screws on two axes. The device is designed for beginner astronomy enthusiasts, provides a direct image (without inversion and reflection) and can be used as a spotting scope.
Sky-Watcher BK 705AZ3
Characteristics declared by the manufacturer:
Telescope type
refractor
Optical scheme
achromatic
Coating
fully multi coated
Lens diameter (aperture), mm
70
Focal length, mm
500
Maximum useful magnification, times
140
Focal ration
f/7
Eyepieces
25 mm, 10 mm
Mounting diameter of eyepieces, inches
1,25
Finder
red dot
Tripod
aluminium
Accessory tray
yes
Telescope control type
manual
Mount type
azimutal, AZ3
Fine tunes mechanism
dual axis
Extras
There is a standard T-thread (M42) for mounting a SLR camera
Orion SpaceProbe II 76 EQ — зеркальный телескоп системы Ньютона с диаметром объектива 76 мм, установленный на экваториальной монтировке. Это телескоп начального уровня, однако при этом он обеспечивает хорошее качество изображения, а монтировка оснащена микрометрическими винтами по двум осям. Лучше всего телескоп Orion SpaceProbe II 76 EQ подойдет для использования во дворе или на открытой площадке, так как его окулярный узел расположен в передней части трубы. Телескоп формирует перевёрнутое изображение — это особенность зеркального телескопа и неисправностью не является.
Orion SpaceProbe II 76 EQ
Заявленные характеристики
Тип оптической схемы
Рефлектор
Тип монтировки
экваториальная
Оптическая схема
Рефлектор Ньютона
Диаметр объектива, мм
76 мм
Фокусное расстояние, мм
700 мм
Относительное отверстие
f/9.2
Разрешающая способность, угл. сек
700 мм
Проницающая способность (звездная величина, приблизительно)
13.2
Минимальное полезное увеличение, крат
11x
Максимальное полезное увеличение, крат
Сферическое
Тип монтировки
Немецкая экваториальная
Особенности приводов
Есть возможность установить электрический привод, приобретается дополнительно
Meade Polaris 90 мм — линзовый телескоп с диаметром объектива 90 мм и фокусным расстоянием 1000 мм на экваториальной монтировке. Это телескоп начального уровня, подойдет для знакомства с небом, однако за счёт достаточно большой апертуры покажет небесные объекты заметно ярче и детальнее, чем телескопы с меньшим диаметром.
