choosing a telescope

Впечатления от трубы телескопа Celestron AstroMaster 76

Celestron AstroMaster 76 OTA
Celestron AstroMaster 76 OTA

Признаюсь – я люблю маленькие телескопы. Люблю за небольшой вес, компактность и быструю готовность к наблюдениям. Хочу сказать, что телескопы с небольшим диаметром (от 70 до 114 мм) очень недооцениваются как новичками, так и опытными астрономами-любителями. И зря!

What Can You See with a Telescope

Actually, this is one of the first questions that arises in most novice astronomy enthusiasts. Someone thinks that you can see an American flag in a telescope, planets the size of a soccer ball, colored nebulae, as in photos from Hubble, etc. If you think so too, then I will immediately disappoint you – the flag is not visible, the planets size like pea, galaxies and nebulae are gray colorless spots. The fact is that a telescope is not just a tube for entertaining and receiving “happiness to the brain”. This is a rather complex optical device, with the correct and thoughtful use of which you will receive a lot of pleasant emotions and impressions from viewing space objects. So what can be seen through a telescope?

Основные функциональные узлы телескопа

Телескоп Celestron Omni XLT 102

Телескоп Celestron Omni XLT 102

Оптическая труба – собственно, труба телескопа. Содержит: объектив, формирующий изображение в фокальной плоскости (состоит из нескольких линз), фокусер (устройство для наведения на резкость).   Окуляр предназначен для рассматривания изображения, формируемого объективом, состоит из нескольких линз. Искатель крепится к оптической трубе, предназначен для точного наведения на объект и представляет собой небольшой телескоп со своим объективом и окуляром.   Диагональное зеркало обеспечивает излом оптической оси на 90 градусов для более комфортных наблюдений.  Монтировка обеспечивает наведение на объект и его сопровождение. На монтировке есть винты тонких движений для более точной наводки. Противовес уравновешивает трубу телескопа.  На треноге держится монтировка и оптическая труба телескопа.

Baader MPCC – review and impressions

Baader MPCC
Baader MPCC

The fast parabolic telescopes of the Newton system have coma – an aberration that distorts the appearance of stars along the edges of the field of view. In the center, the stars look like dots, but when they approach the edge of the field of view they turn into small “comets.” Coma corrector is an important accessory that can significantly reduce or even completely compensate for this aberration. It is especially needed for astrograph telescopes with a relative aperture of 1: 4 … 1:5. For visual observations with a relative aperture of 1:5, you can still do without a coma corrector, but at 1:4 its use is very, very desirable.

Coma of 200-mm mirrors with different f/ratio and different distance from axis
Coma of 200-mm mirrors with different f/ratio and different distance from axis

FAQ about lunar and planetary astrophotography

1. What is the difference of lunar-planetary shooting from other types of astrophotography?
When shooting planets, use a short shutter speed (from 1 100 s to 1 s), a relative aperture from 1:20 to 1:40 and the addition of several thousand frames. The clearest frames are selected, therefore it is possible to improve the signal-to-noise ratio and minimize the influence of the earth’s atmosphere.

Single stack and stack of 500 frames wih deconvolution and normalization

2. How does the planetary survey technique look like?
We get a video of the planet, crop and align it, then in a special program we select clear frames and stack them. We apply wavelets or deconvolution to the result of stacking – we restore the details and sharpness of image.
Manual for capturing and processing planets
Manual for capturing and processing lunar and solar movies

3. I want to try myself in a planetary photo. Where to begin?
To decide on the equipment – choosing telescope and a camera. Any telescope with high-quality optics and minimal aberrations in the center of the field of view will be suitable for shooting planets. You can get good shots with a small aperture (90-102 mm), but the recommended aperture is from 150 mm. If you already have a telescope – check whether it is in the black list.
The simplest photos of the planets can be obtained by capturing through the eyepiece of a telescope.

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