Macro extension ring for M42 42mm screw mount lenses, compatible with film, digital, and SLR camera lens mount adapter rings Macro extension ring for M42 42mm screw mount lenses, compatible with film, digital, and SLR camera lens mount adapter rings Macro extension ring for M42 42mm screw mount lenses, compatible with film, digital, and SLR camera lens mount adapter rings Today's Outfit Features: Brand New, High Quality This M42 close-up adapter allows for new shooting methods. It consists of three adapters. The adapters are installed between the system camera body and the lens, and can be combined in any way to achieve the desired magnification. There are three parts in total that can be used individually or in combination, but the aperture cannot be linked. The lengths of these three parts are 7mm, 14mm, and 28mm respectively, achieving a 1:1 magnification ratio when paired with a 50mm lens. The conversion formula is: Magnification = Adapter ring length / Lens focal length. Based on this formula, multiple adapter rings can be combined to match different lenses, thus achieving the desired close-up effect. The close-up ring on the M42 mount can turn a regular lens into a macro lens. Due to differences in monitors, the colors in the image may differ slightly from the actual product.