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Telescope Filters \u2013 Why Do We Need Them?<\/span><\/h2>\n
The basic principle of filters is to emphasize light of certain wavelengths (colors) and suppress others. This makes it possible to emphasize characteristic details of the disks of planets or nebulae. Thus, you can safely observe the Moon or the Sun without fearing for your own health. Astronomy filters<\/a> have been specifically designed for safe observation of the night sky.<\/p>\n
What are telescope filters?<\/span><\/h3>\n
A color filter is an important, sometimes even necessary, accessory for telescope observations. Such filters for telescopes can be divided into several types: solar filters, colored planetary filters, and narrowband filters for observing and photographing nebulae.<\/p>\n
Solar filters are used to safely observe the disk of the Sun. Under no circumstances do we recommend observing the Sun through a telescope not equipped with a special filter. As 99.999% of visible light is cut off by solar filters, it is absolutely safe to observe the Sun when using it. A solar filter must be worn on the telescope lens. That is, the inner diameter of the solar filter must be equal to the outer diameter of the telescope tube. Observing through an ocular solar filter is not safe because the sun’s rays cause heating and may result in filter cracking! Observing the Sun can cause heating and damage to the filter attached to the eyepiece.<\/p>\n
The most budget-friendly version of a solar filter is to make the filter to the diameter of the telescope using special solar film. Such film is also completely safe and gives a rich contrast picture. Depending on the film manufacturer, the color of the solar disk may vary when observing. Also, a distinction is made between visual and photographic film. For safe visual observations, only visual film is suitable.<\/p><\/blockquote>\n
Another option is off-the-shelf glass solar filters designed for a specific telescope tube diameter.<\/p>\n
![\"solar](\"https:\/\/alloptica.com\/wp-content\/uploads\/2022\/06\/solar-filter-for-sun-observation.jpg\")
<\/p>\nHow do telescope filters work? Why do we use telescope filters?<\/span><\/h3>\n
Color filters are used mainly for visual observations of the planets. Such filters make the image of the planets more contrasting and highlight details on their surface. Colored filters include a neutral gray or green colored lunar filter that mutes the brightness of the moon, making observations more comfortable.<\/p>\n
The red filter is used for daytime observation of Venus, observations of the polar caps on the surface of Mars, and blue clouds on Jupiter. The orange filter is very useful for observing the Moon, for daytime observation of Mercury, for detailing the surface of Mars, belts and festoons on Jupiter. The yellow filter enhances the surface contrast of Venus, increases the visibility of seas and clouds on Mars and belts on Jupiter. The green filter enhances detail contrast on the Moon, improves detail contrast on Venus, and is useful for observing Mars’ shoulder storms and polar caps.<\/p>\n
Special narrow band filters are filters that cut off certain wavelength ranges, leaving a narrow bandwidth of radiation. Such filters are used both for visual observations and for astrophotography of deep space<\/a> objects emitting in a certain spectrum.<\/p>\n
Types of telescope filters<\/span><\/h3>\n