What's the difference between the Variable Polarizing filter, the Neutral Density Moon filter, and the Moon filter?

What’s the difference between the Variable Polarizing filter, the Neutral Density Moon filter, and the Moon filter?

Viewing the moon on your new telescope is among the best experiences ever. After all, the moon is so beautiful. The moon is the most looked-at heavenly body on a telescope.

Most telescopes can attach filters. These filters can have many purposes. For example, there are special telescope filters that filter color.

Similarly, there are a few filters designed for moon observation too. They make your moon observation better and safer. Why do you need safety for moon viewing?

The moon is bright. However, looking at it through a telescope makes it many times brighter. When focused through a telescope, the moon’s brightness might damage your eye.

A filter also reduces the moon’s brightness. This clarifies the image so that you can see it properly. Not only that, but the best filters perform many more important functions.

For instance, they cut back on glare and light scatter. Also, they increase the resolution and definition. With selection filtration, many filters increase the contrast as well.

Consequently, you get a picture that has less irradiation and, thus, minimal eye fatigue. For these reasons, such eyepiece filters are essential for planetary and lunar observation.

These eyepiece filters are available in many types. Here, we will explain the difference between the most common ones. These are the Moon filter, the Neutral Density Moon filter, and the Variable Polarizing filter.

Moon Filters

In simple words, a moon filter is like sunglasses for your telescope. Most telescope eyepieces have threads for filters. Therefore, a moon filter fits directly on the bottom of an eyepiece.

Moon filters reduce the brightness of the moon so that it doesn’t irritate your eye. For example, the 05662 Orion moon filter blocks 87% of the moon’s light.

Moreover, moon filters decrease glare, improve contrast, and accentuate the details of the moon. These filters are mostly low technology and, therefore, inexpensive.

That being said, there is a downside to most moon filters. They impart a tinge of green color to the moon that most users don’t like.

Neutral Density Moon Filter

The neutral density moon filter has the same purpose as the variable polarizing filter. These filters also reduce the amount of light going through the eyepiece of a telescope.

The neutral density moon filter also does its job without compromising the overall image color. However, there are a few downsides to this astronomical filter.

A neutral density moon filter offers a fixed amount of light reduction. For example, Celestron’s 94105 filter reduces the amount of incoming light by 87%.

As a result, you would probably need multiple neutral density moon filters. The number of these filters you need depends on the moon phase or magnification.

A neutral density moon filter effectively increases a bright image’s contrast, like those of Jupiter. Also, they’re suitable for reducing glare and dimming bright light to split close double stars.

A high-quality neutral density moon filter usually features threads on both sides. This is helpful for users wanting to add extra filters, such as a color filter.

Variable Polarizing Filter

A variable polarizing filter changes the image brightness. This allows telescope users to observe the moon in a better way.

Many variable polarizing filters use a glass with an aluminum cell. Most manufacturers design them to have threads on both sides. This allows them to be stacked with color filters.

It allows you to view not only the moon but also other planets. With this filter, you can filter light transmission over a range from 1-3% to 40%.

Variable polarizing filters consist of two polarizing layers. You can rotate these layers independently to change the amount of transmission of the filter.

These layers help lower the amount of light getting through your telescope. And they do so without affecting the colors of the image. They improve the contrast of the image.

As a result, the moon’s features appear more detailed. This is particularly helpful for viewing the moon when it’s near full.

Besides that, a variable polarizing filter can show double stars, where one is significantly brighter. Also, you can use it to darken the sky while looking for planets.

Remember, be careful that you don’t use variable polarizing filters for viewing the sun. For that, there are special solar filters, specially designed for their purpose.


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