a series of camera operations steps s17 18 the reason why the focusing motor is reset after winding on the film is to reset the second lens group 15 to a predetermined position for the purpose of quickly finishing the next focusing operation however such a resetting may be dispensed with in the lens barrel of the third embodiment the position of the second lens group 15 is detected at only a particular point and therefore whether the second lens group 15 has reached the target position or not cannot be directly determined by using the third lens group 16 as a reference accordingly as with the prior art shown in fig5 the target position of the second lens group 15 is set as the number of drive pulses and the second lens group 15 is stopped at the time the set pulse number is detected while counting the drive pulses applied to the focusing motor 114 fig1 shows a fourth embodiment of the present invention in which a fixed frame 51 of the lens barrel supports a lens 56 as well as a right hand end of guide shaft 57 support ring 52 which is fixed at the front end of fixed frame 51 supports the left hand end of guide shaft 57 so that its axis is substantially parallel with optical axis o a dielectric core 58 is fixed on guide shaft 57 in substantially the same manner as the dielectric core 28c shown in fig1 or the dielectric core 36c shown in fig2 a lens holder.