PURPOSE:To perform easily a focusing operation under an interlocked condition to a lens exchanging operation, by differentiating the moving distance of a projecting lens selectiely mounted by the same operation of focusing performed under a condition which is engaged with a lens holder. CONSTITUTION:A lens holder 5 is mounted attachablg and detachably on a supporting member 3 fixed to the substrate 1 of a film leader and a lens 8 for high magnufication is put in the outer barrel 7 of the holder 5. Focusing is performed by rotating a shaft 11 and moving the lens 8 upward and downward through gears 13 and 10 and an inner barrel 7. The lens holder 5 fitted with a lens 16 for low magnification is mounted on another supporting member 4 and forcusing is performed in the same way by rotating the shaft 11. Since the transmitting route by the gears is different for lenses of high magnification and low magnification, the moving distance of the low magnification lens 16 becomes greater than that of the high magnification lens 18. Therefore, the focusing operation which is performed under a condition interlocking to the lens exchange becomes easier.
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