This Lumicon 82A Blue 1.25" Filter is a light balancing filter used to increase the color temperature slightly for a cooler tone. This blue filter absorbs the excessive yellow-red light from daylight in the morning. In celestial photography, this filter may "cool down" the reddish tones found in certain stars or planets. For planetary observing, color filters bring out the most detail because planets are naturally colorful. Different colors bring out different details of the planet you are viewing.