You could more easily resolve a close double star with a blue filter than with a red one.

Question

Quizplus · Accepted Answer

Blue filters have a shorter wavelength than red filters, meaning they have higher resolution and can more easily distinguish between closely spaced objects, such as a close double star. Blue light has a shorter wavelength and higher frequency than red light, which means it can provide sharper images and improve resolution. As a result, using a blue filter can make it easier to distinguish between the two stars in a close double star system.

You Could More Easily Resolve a Close Double Star with a Blue