在之前的文章中，我们探讨了天文摄影的光谱和改机技巧，而这篇文章将深入讨论如何利用滤镜来提升我们的拍摄效果。

首先，让我们回顾一下电磁波谱图。在这个图表中，我们了解了可见光波段，通常为380-780nm。这时，如果使用普通相机进行拍摄，由于内置滤镜会阻挡宇宙中的Hα等波段，为了更好地捕捉这些信息，我们需要进行改机，即取下或替换原本相机内置的滤镜。

【What are astronomical filters?】

Astronomical filters are not like the ones used in everyday photography, as seen below.

Instead, we use specialized filters like these:

【Why do we need filters?】

Our cameras can only sense black and white; therefore, we require specific color filters to capture certain wavelengths of light. We often see colorful images produced by cameras that have a Bayer array (tiny red, green, and blue filters) built into them. This allows for color images to be captured in one shot.

In astronomy photography, just as with daily photography, various filters serve different purposes. For example:

Wideband Filters: These include UV/IR CUT and LRGB (Luminance + Red + Green + Blue). The former cuts off ultraviolet and infrared light while allowing visible light through.

Light Pollution Filters: Designed to block artificial light sources' spectral bands while passing celestial emission lines.

Narrowband Filters: Allow only specific wavelengths of light through; e.g., Hα (656.3 nm) is an important line for astronomers.

【Types of Astronomical Filters】

Filters can be classified based on their bandwidths and uses:

Wideband Filters: Examples include UV/IR CUT and LRGB.

Light Pollution Reduction (LPR) or Ultraviolet H-alpha (UHC) Filters: Designed to reduce sky glow caused by artificial lighting.

Narrowband Filters: Filter out all but a narrow range of wavelengths around a specific emission line or absorption band.

For instance:

UHC Filter

Lpro Filter

ClearSky Filter

STC Astro Nightscape/Astro Multispectra

IDAS LPS P2

Each filter has its unique characteristics:

- **UV/IR CUT**: Blocks ultraviolet (< 380 nm) and infrared (> 780 nm) radiation from entering the camera sensor.

- **Light Pollution Reduction**: Helps minimize the impact of city lights on deep-sky imaging by blocking unwanted artificial spectrum emissions while transmitting celestial emission lines such as hydrogen alpha at 656 nanometers.

- **Narrowband**: Allows passage only within a very narrow range around specific wavelength(s), typically centered at an emission line characteristic of a particular astronomical object type or phenomenon.

By using these specialized tools combined with advanced techniques like image processing software post-processing manipulation techniques—astronomers can create stunning visual representations capturing both details about our cosmos as well as beauty inherent within it all!