Baader Solar Filters provide a safe way to observe and photograph the sun with AstroSolar® ClearWhite Safety Film OD 5.1 in the best possible quality. Many homemade filters stretch the filter material tightly to make it look like a glass filter. However, this reduces image quality and makes the filter unusable for higher magnifications. AstroSolar® Safety Film must be mounted completely free of tension to act like a highly precise, plan-polished optical window. Although this may seem contradictory to common quality perceptions, AstroSolar® must show slight waves. Only when the filter material is subjected to tension due to an inadequate mount does it perform no better than a simple glass filter made from untreated window glass.