Astronomy filters can be used to improve both visual observing and imaging. Unfortunately there is no one size fits all solution so we are working on this section of our website to give you a clearer understanding of what each type of filter can do. Light pollution filters are the most commonly asked for filter and we have a dedicated section that features a comprehensive range of solutions. In addition to that we have a range of filters suitable for a variety of imaging applications as well as filters designed to enhance your visual observing.
You will see filters sometimes described as visual, photographic or CCD, but despite these classifications some filters can be used for more than one application. The key point to understand is how much light they will let through. A Digital camera or CCD chip is much more sensitive than the human eye and in addition can be programed to take long exposures. This means they can work with much less light than the Human Eye so typically a photographic or CCD filter will be more aggressive in cutting out light. The most aggressive filters are referred to as narrowband filters and this type literally blocks all light except a specific pre-determined wavelength. You could argue that these are the ultimate light pollution filter! but unfortunately many of them will not allow enough light through for you to see anything with your eye through a small telescope. Because narrowband filters only let through such a small bandwidth of light, your chosen filter must also match the light that is being emitted by your target object. This is why you will see many different options available such as OIII, Hydrogen Alpha, Hydrogen Beta, UHC and more. If you are using a larger telescope of 8 inches or more you can sometimes use a 'photographic' filter for visual use because of the amount of light you can gather, but this is very dependant on how tight the bandwidth is.
Chosing the right filter is therefore all about the balance of cutting out as much unwanted wavelengths of light as possible, but letting enough light through for your eye or camera to process, through your chosen equipment, looking at your chosen target. With so many choices we are always happy to give advice and help you find the best equipment for your use.