THE BEST TELESCOPE FILTERS.

 

Telescopes are complex instruments that help us see faraway objects which makes it a wonderful equipment to observe the night sky. As you can imagine, to achieve that telescopes use very sophisticated systems of optics arrangement involving mirrors, lens, microcontrollers and sometimes even small computers that work in conjunction to bring to us the visual feed.

 

But even then, the best telescopes often fail to produce images that are sharp and has a balanced contrast. To overcome that, we commonly use a telescope filter.

 

What are eyepiece filters.

Video by Celestron

 

 

Visible light emissions are usually capped in the range of 380 to 780 nanometres: from the short wavelength blue-violet end to the long wavelength red end. When observing a particular astronomical object in a telescope, you can often improve contrast by the use of an appropriate filter. The filter works by simply blocking out a portion of the visible spectrum while allowing a certain subset of it to pass through. There are filters in all conceivable colours that are often used for Lunar and planetary observing.

 

Our eyes have various sorts of photoreceptors which see various wavelengths of light. Filters work by controlling the kind of light our eyes see (obstructing certain wavelengths and enabling explicit ones to pass), and by deciding the measure of light that are directed towards our eyes (the percent of transmission).

 

 

Filters are not all alike. One would cut glare and make it simpler to see a full Moon with more noteworthy detail, whereas another will be intended to just transmit explicit hues on the range, and improve contrast when watching the planets.

 

Since the Moon, planets, nebulae and so on all have remarkable cosmetics, we need various filters for each. Numerous filters can be utilized for review of different features of a variety of celestial objects.

 

 

Types of filters.

 

The Moon filter.

 

A moon filter is generally used as a counterbalance to the glare of the sun. It lessens the intensity of the moonlight and makes the images produced more sharp and contrasted. Anyone who has ever been to an observatory and looked at the Moon through a large telescope without a filter will vividly remember the experience and know why this filter is so important. Observing the moon without a filter will not cause any damage, but it is so bright that it really dazzles you.

 

If you then turn away from the telescope and look into the darkness you will often still have a ghostly afterimage of the moon in the eye you observed with. Although this afterimage will gradually fade, it is still very irritating. Of course these filters are available in different light reduction levels. They range from a light transmittance of about 8% up to 50%. The filters with a high transmittance are suitable for the smaller telescopes and those with a low transmittance are suitable for larger telescopes.

 

How to use Moon filters.

Video by Orion Telescopes & Binoculars

 

Adjustable polarizing filters are basically considered an upgrade of Moon filters. This is not just one, but two filter elements, which are connected to each other. Rotating one filter element relative to the other continuously adjusts the amount of darkening. Polarizing filters in general allow about 1% to 40% of light transmission levels. They can be handy in precisely setting the balance between light levels and contrast for your telescope configuration.

 

The Nebula filter.

 

These are filters that are exclusively manufactured for deep sky observation. These are quite complex and costly to produce. They consist of multiple dielectric layers which are vapour deposited onto high-quality optically flat glass. They have the task of only passing a well-defined range of the light spectrum, depending on the type of observing the filter is to be used for.

 

As a rule, spectral regions which are of no interest are absorbed and the spectral regions in which the objects mainly radiate are allowed through. The image seen in the telescope is darkened slightly.

 

When you look at the transmission curve of any of these filters, you will notice that there is a significant drop in transmittance in this area and the curve only rises again above 630nm. These filters are enormously effective as they block the street light while, at the same time, increasing contrast in the object being observed.

 

 

The Solar filter.

 

It is conceivable to safely observe the sun. Unlike the rest of the filters discussed here, appropriate solar filters are not threaded for an eyepiece. The issue with a filter like this is the telescope will end up concentrating an excessive amount of solar light through its primary optics before reaching the eyepiece filter thus harming its composition. A damaged filter wouldn’t help in protecting your eyes.

A solar filter will generally, instead of covering the eyepiece, position over the front lens of your scope in a way that it covers the whole face of the primary optic. Such a filter should be fitted to the definite aperture of your telescope to be viable. These channels shut out 99.9% of the Sun’s light before it enters the telescope.

 

 

Color filters.

 

As the name suggests, these filters filter out colors; hindering certain hues and enabling others to pass. This is exceptionally valuable when observing our solar system, as planetary surface detail and differentiation is expanded.
The Wratten System is utilized for requesting the distinctive color filter types.

An essential four color set is perfect for a beginner, and will for the most part incorporate blue, green, red and yellow.

 

 

Using filters with your telescope.

 

Using a filter with a telescope is quite simple: you have a choice between using 1.25″ or 2″ filters. These sizes correspond to the eyepiece format on your telescope and all you have to do is to screw your filter onto the thread in the eyepiece barrel provided for it. You then put the eyepiece, including the filter, into the focuser of the telescope and you can start observing immediately. There is a huge range of astronomical accessories out there, and this book only covers a small selection – those which are of interest to beginners in amateur astronomy.

 

 

Best filters for you to consider.

 

Orion 5562 2-inch Variable Polarizing Filter.

 

The filter enhances solar system observation by essentially diminishing the measure of glare produced by the sun and other nearby star systems. This makes it perfect for watching the full Moon in more noteworthy detail. The other helpful component is that you can alter the measure of light transmission from 1 % to 40% by just rotating it. Find the latest price in Amazon find it here.

 

 

Orion 5657 2-inch Ultrablock Narrowband Eyepiece Filter.

 

This is a good filter to have for observation of deep sky objects under dimly lit polluted skies. This filter obstructs all types of light pollution emissions, for example, the Mercury vapor and Sodium emission groups. This is useful for distinguishing dimmer emission nebulae. Find the latest price and reviews on Amazon here.

 

 

Meade Series 4000 Filter: ND96.

 

This neutral filter transmits light over the total visual range. At 13% transmission, it is ideal for decreasing glare and review an assortment of planetary bodies. This filter additionally isolates adjacent double stars (when their dimensions of brilliance vary). Find customer reviews and the latest price on Amazon here.

 

 

Astromania 2-inch Narrowband H-Beta Filter.

 

Astronomania’s H-Beta filter removes light pollution while as yet keeping up over 90% light transmission. This implies you can get strong perspectives on fainter targets. This filter works best with bigger aperture telescopes, and when skies are bright and clear. Find the latest customer reviews and latest price on Amazon here. 

 

 

Orion 07798 4.57-inch ID Full Aperture Solar Filter.

 

Securely see the sun with this quality Orion solar filter. It fits the front aperture of effectively measured telescopes consummately, shutting out 99.9% of daylight before entering the cylinder. The filter rejects bright and infrared radiation, and improves contrast without losing the characteristic shades of the Sun. This filter can likewise be utilized for shooting the Sun. Find the latest customer reviews and price on Amazon here.

 

 

Related questions.

 

What are telescope filters used for?

Like a photographic filter, telescope filters enhance details and improve contrast. They do this by cutting out unwanted colors, or wavelengths of light. Professional astronomers may use filters for technical observations, such as classifying stars.

 

Do light pollution filters work? If so, how?

Light pollution reduction (LPR) filters work because many outdoor lighting sources do not shine evenly across the visible spectrum. Instead, they emit radiation at only a few distinct wavelengths. LPR filters suppress those and similar wavelengths while allowing others through.