Filters

General Features

There are more specialized filters, such as light pollution that filter wavelengths from nothing more than public lighting (mercury and sodium in particular). Others such as nebulae filters (those of ionized oxygen for example) are quite expensive, but they can enhance quite a picture.

A particular type of filter is solar. They come in different classes, depending on the observer. The most common and economical are those that simply filter to decrease the brightness of the image and prevent the transfer of dangerous radiation. There are many other more sophisticated as the Hydrogen Alpha, which only let through a narrow band of radiation, thus being able to observe phenomena like solar flares.

Regarding the former, there are two popular models: the glass and Mylar. The glass is often recommended (always talking about fully open filters that cover the entire telescope entreda light), being more thermally stable and not as fragile as Mylar loa. The Mylar is a flexible sheet in which material is deposited planned to filter out harmful radiation. These filters usually appear "wrinkled", which should be as well to avoid tearing the temperature differences. The Mylar is more expensive than glass.

Color filters Telescopes

There are different types of filters for telescopes, some details about them:

• Light Yellow (Light Yellow) - 83% transmission. Theses filters are used to see red and orange detail at the atmosphere of Jupiter. It is useful to contrast dark areas of Mars. Also it can be used to highlight the details of the surface of the moon.
• Greenish yellow (Yellow-Green) - 78% transmission. It is used to increase the contrast of red and blue zones of Jupiter and Saturn. It Improves the clarity of Cassini, the moon of Saturn.
• Yellow - 74% transmission. Highlight the red and orange features on Jupiter and Saturn. It is a good contrast to the blue and green areas of Mars. It serves to increase the contrast of the moon for telescopes of more than 6 inches.
• Orange (Orange) - 46% transmission. Reduces or eliminates the wavelengths of blue and green. It is useful to increase the details of the polar zones and belts of Jupiter and Saturn. It clarifies the boundaries between the different areas of the Martian surface.
• Light red (light red) - 25% transmission. It is used in telescopes bigger than 6 inches. This kind of filter can eliminate the blue and green waves. It is used to see Jupiter, Saturn and Mars. This filter increases the contrast between the evening sky and Mercury on observations near sunrise or sunset.
• Red - 14% transmission. Eliminates or reduces the blue wavelengths and green. Used for observing the polar regions of Mars. It is recommended for telescopes larger than 8 inches (203mm) diameter because it has low light transmission.
• Dark Blue - 17% transmission. It is used almost exclusively to observe Jupiter. It is also useful to study the Martian atmosphere and Saturn's cloud structures.
• Violet - 3% transmission. This filter absorbs a large amount of green, red and yellow waves. It is used to observe the polar regions of Mars and to study phenomena that occur in the polar regions of Venus. It increases the contrast between the rings of Saturn. Violet filter can only be used on telescopes bigger than 8 inches (203 mm).
• Light green - 56% transmission. It's great to watch the polar regions of Mars and storms on its surface. Increases contrast between blue and red areas of the atmosphere of Jupiter.
• Green - 24% transmission. It make more visible and belts of the polar region of Saturn. It increases the contrast of the Martian poles and atmospheric phenomena on Venus. It can be used in telescopes larger than 8 inches (203mm).
• Azul (Blue) - 30% transmission. It increases the contrast of Jupiter's belts, increase the visibility of details of Saturn's belts and polar phenomena. It is widely used to contrast the lunar surface.
• Blue (Light blue) - 73% transmission. Increases contrast and does not absorb too much light. It is used for observations of Mars, Jupiter, Saturn and Moon. It is very useful in combination with others.
• Density of 0.9 - 13% of transmission. Transmits all the wavelengths of the spectrum, is a neutral density filter. It is very useful to reduce glare in lunar observations when using telescopes larger than 4 inches. It is used to observe double stars when one of them is brighter than the other.