Let’s start with a brief explanation what an extension tube is… In basic terms, it is a hollow cylinder that fits between your camera and lens, moving the lens further away from the sensor and therefore allowing it to focus more closely, with a larger magnification factor. Some come with electrical contacts, others don’t. The ones that do normally keep all of the communication between the camera body and the lens going; IOS, Autofocus, etc… The longer the tube, the closer the focus distance becomes, but also the more the distant/infinity focus is affected. Because there are no glass elements in extension tubes (hollow tubes), most photographers tend believe that there is no difference in the image quality compared to shooting without them. However because lenses are always optimised for a specific distance between the lens and sensor-plane, there can be a reduction of sharpness towards the edges of the frame. Given the depth of field is so limited to start with, this is often not a big issue…..