The Canon EF 25mm Extension Tube II is used to allow a lens to focus closer than it does natively. This is accomplished by moving the lens 25mm farther away from the camera body's film plane or digital sensor by fitting between the camera body and the lens.
The Canon EF 25mm Extension Tube II is updated to be fully compatible with Canon Digital EF-S lenses, as well as standard photo EF and TS-E lenses. Autofocus and auto exposure are maintained when using these compatible lenses. There is a bit of light lost when using the Canon EF 25mm Extension Tube II. Functioning auto exposure will take care of correcting the exposure for you
The Canon EF 25mm Extension Tube II is recommended for lenses with a focal length of 50mm and up For example, the Canon EF-S 18-55mm Lens should be used only at its mid and long focal lengths with the Canon EF 25mm Extension Tube II installed.
The Canon EF 25mm Extension Tube II is commonly used for macro photography. When evaluating the Canon EF 25mm Extension Tube II, I needed to make the Canon EF 300mm f/2.8 L IS Lens focus closer than its long native minimum focusing distance - more like the Canon EF 300mm f/4 L IS Lens.