A ring flash adapter of the flash uses a clamping device attached to the external flash of the camera, and using the lightguide (1) the, light can be transmitted from the flash into circular body. The lightguide has a flat circle and a head with an incidence surface and a reflecting surface. The lightguide also has an even number of separate, parallel, inter-connected shaped belt segments inserted in the head. The foreside of the circle forms an emission surface; the rear side is provided with a system of "V" shaped teeth to reflect light on the emission surface.