Yes, DSLRs' physical color and light pollution filters can achieve things that can't be done in post.
When it comes to color filters, they play a fascinating role in photography. These filters can selectively absorb specific wavelengths of light while allowing others to pass through. As a result, they have a direct impact on the overall color balance of an image. For instance, a red filter will absorb blue and green light, letting only red light reach the sensor. Consequently, the image will exhibit a prominent reddish tone, which wouldn't be possible without the filter.
Post-processing techniques offer a wide range of adjustments, including color balance, but they cannot replicate the exact effects of a physical color filter. The reason lies in the fundamental difference between the two. A physical color filter interacts with the light before it reaches the camera's sensor, modifying its composition. On the other hand, post-processing manipulates the captured light data after the sensor has recorded it.
Turning our attention to light pollution filters, they aim to counteract the adverse impact of artificial light sources, such as streetlights. By absorbing specific light wavelengths emitted by these sources, light pollution filters facilitate the visibility of faint celestial objects in the night sky, including stars and galaxies.
While post-processing techniques can help reduce the impact of light pollution through methods like gradient removal, this process tends to be time-consuming and meticulous. In contrast, a dedicated light pollution filter offers the advantage of automatic filtration, effectively eliminating unwanted light pollution. Additionally, it can enhance the overall contrast and clarity of the resulting image.
Here are some examples of how color filters and light pollution filters can work differently than post-processing:
Color filters can be used to create artistic effects. For example, a red filter can be used to create a more dramatic sunset or a blue filter can be used to create a more surreal landscape. You can create similar effects in the post, but controlling the results will be more difficult.
Light pollution filters can improve the visibility of faint objects in the night sky. For example, a light pollution filter can be used to make it easier to see the Milky Way or to capture the details of a nebula. In the post, you can reduce the amount of light pollution in an image, but you may not be able to see as many faint objects.
In my personal experience, I have found that color and light pollution filters can be very effective in achieving certain effects that are difficult or impossible to recreate in a post. However, it is important to experiment with different filters and settings to find what works best for you.