We learnt about telescopes and several properties of light for today's lesson for Astrochallenge. We learnt about the types of telescopes (reflectors, refractors and compound), and several equations. The focal ratio (f-number) is the focal length divided by the aperture. The lower the focal ratio, the lower the magnification, field of view and the dimmer the image produced. The field of view is how much of the sky you can see with your telescope. Magnifying power is the ratio between the dimensions of the image produced and the object. Light-gathering power is the number of photons collected by a telescope per second. Eye relief refers to the distance you should hold your eye from your telescope for the best view.
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| By Krishnavedala - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=34874191 |
Refractors use refraction, reflectors use reflection, and compound telescopes use both. Refractors suffer from chromatic aberration. They are easier to maintain as the tube is sealed, preventing dirt from entering. Reflectors suffer from comatic aberration, and dirt can enter as the tube isn't sealed. They are cheaper than refractors.
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| By ぷんすけ - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=50791096 |
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