Extension Tubes are designed to enable a lens to focus closer than its standard minimum focus distance. This has the effect of magnifying the subject so that it appears larger in the viewfinder and resulting images. Extension tubes are exceptionally useful for macro photography, allowing almost any lens to be used for close-up work, maintaining its original optical quality at a fraction of the cost of a dedicated macro lens. Kenko's Auto Extension Tubes contain all the circuitry and mechanical coupling to maintain autofocus and TTL auto exposure with most lenses, providing there is enough light. The Kenko Extension tubes have been updated to work with both the Canon EF and EF-S lenses.