When we practice macrophotography we move into the field relationship expansion relatively small, less than 1. In these circumstances the best option is a macro lens that can be used without extension tubes, so you can work from infinity to an extension ratio 1. Under these conditions we photographed a bee. We recommend a rather long focal length, 100 mm higher in order to take photos at about 30 cm from the subject.
If you have a macro lens, the normal order of 50 mm is an excellent target for a very affordable price (considering the value for money). With extension tubes can work up to a ratio of slightly more than 1 extension that allows us to take a picture of a fly. Recommend that extension tubes have contacts for maintaining the automatic camera.
We will focus distance manually, approach or move away from the subject. The autofocus of the camera more nuisance than service in these conditions but you can focus and shoot with the aperture open without worrying about closing it will help us a lot.
Under these conditions we can take pictures with natural light and very often with the aid of a flash or older. Must be the TTL flash so that it can be regulated by the light of the information received by the sensor or you can shoot to different powers to adjust the power of the flash to subject distance and the diaphragm used. With digital cameras this can be done by trial and error.
The normal position of the flash on the camera usually does not help us, please give it more separated from the camera, and this involves using a sync cable between the camera and the flash or shoot it remotely with photocells or with remote controls.