Canon Extension Tube FD25 for 50mm F/3.5 Macro SLR Lens

The Canon Extension Tube FD25 is an accessory used to enable closer focusing distances on Canon FD-mount lenses, such as the Canon 50mm f/3.5 Macro lens. Here's how it works and what it offers:

1. Extension Tube Functionality: The extension tube is essentially a hollow tube that fits between the camera body and the lens. It moves the lens farther away from the camera's image sensor, which allows for closer focusing distances without sacrificing image quality.

2. Closer Focusing: By using the FD25 extension tube with the 50mm f/3.5 Macro lens, you can focus on subjects much closer than you could without it. This is particularly useful for macro photography, where you want to capture small subjects at high magnification.

3. Compatibility: The FD25 extension tube is specifically designed for use with Canon FD-mount lenses, such as the 50mm f/3.5 Macro lens. It's essential to ensure compatibility with your specific lens and camera body.

4. No Optical Elements: Extension tubes like the FD25 don't contain any optical elements, so they don't affect image quality or introduce additional optical aberrations. They simply move the lens farther from the camera, altering the focusing range.

5. Manual Focus: When using extension tubes, focusing is typically done manually. This is because the increased distance between the lens and the camera body may prevent the lens from communicating with the camera's autofocus system.

6. Magnification Factor: The magnification achieved with an extension tube depends on its length and the focal length of the lens. The FD25 tube, being 25mm long, would provide a moderate increase in magnification with the 50mm macro lens.

7. Versatility: Extension tubes are versatile accessories that can be used with various lenses to achieve macro or close-up photography. They are particularly useful for photographers who want to explore macro photography without investing in dedicated macro lenses.