MECHANICAL ADVANCING HANDLE THAT SIMPLIFIES MINIRHIZOTRON CAMERA REGISTRATION AND IMAGE COLLECTION

Minirhizotrons in conjunction with a minirhizotron video camera system are becoming widely used tools for investigating root production and survival in a variety of ecosystems. Image collection with a minirhizo tron camera can be time consuming and tedious particularly when hundre ds or thousands of images are collected routinely, To help us with ima ge collection in our minirhizotron studies we developed a mechanical h andle that simplifies minirhizotron camera registration and image coll ection. The handle is attached to the minirhizotron camera and fits in side 5 cm, internal diameter, minirhizotron tubes. The handle couples a ratchet advancing mechanism with another mechanism that locks the ha ndle to the minirhizotron tube, ensuring proper camera and tube regist ration. The ratchet mechanism advances the camera one camera field of view (frame) at a time. While the handle can be used to rapidly advanc e the camera, it is best to pause 2 to 3 s after each advance, to allo w sufficient time for the image to be recorded on video tape. At this rate, 20 to 30 frames can be recorded each minute. The camera, with ha ndle attached, is easily moved from one minirhizotron tube to another. We conducted a simple study of handle performance and estimate that c amera registration precision (a measure of relocating the camera in th e same position) is >99%.