is mounted so that it faces the camera head 18 the second light source 34 is forward facing i e it is mounted so that it faces away from the camera head 18 because the light sources are spaced from the camera lens 24 by the length of the extension legs and further because of the tandem arrangement of the light sources 32 and 34 each light source is spaced from the camera lens by a different distance the two light sources 32 and 34 will thus illuminate different parts of the pipe 12 this effect is shown in more detail in fig4 a and 4b in fig4 a and 4b the effect of light placement is diagrammatically shown in fig4 a a pipe 36 which has a relatively small diameter is under inspection by the instrument probe 10 as shown the field of view 28 of the camera encounters the pipe at a close distance from the camera in this case the first light source 32 is energized to illuminate the pipe 36 in the field of view 28 the second light source 34 is farther from the camera and in this case the portion of the pipe 36 which it would illuminate is blocked from the field of view 28 of the camera by the light head itself thus the second light source 34 would be placed in a deenergized state in the application shown in fig4 b a pipe 38 of larger diameter is under inspection by the instrument.