This B+W 900 collapsible lens hood, 55 mm, is made of a high-quality rubber material and its aperture angle is suitable for standard lenses. The inner ribbing enhances the light-absorbing effect of the matte black surface. It is nicely compact and can be collapsed by compressing.
Lens hoods, occasionally known as lens shades , keep away the light that would otherwise fall on the lens from outside of the aperture angle. This prevents situations where unnecessary light on the lens surfaces and edges could be reflected – diffuse or focused – within the lens barrel and the camera body. Because this kind of stray light veils the image or superimposes light spots and "ghost images", it degrades the contrast. Lens hoods can thus contribute significantly to improving the image quality, especially when light comes obliquely from the front and where the subject has very bright surroundings that are outside the frame.
The lens hood is an essential accessory for better pictures and should always be used to prevent flare. As well as shielding stray light, lens hoods also provide effective physical protection of the delicate front lens against raindrops, accidental contact (fingerprints reduce the contrast considerably!) and from accidental knocks and bangs.
B+W lens hoods have an all-purpose design and fit many different lenses.