the alternative version of the invention illustrated in fig9 through 12 or a variation thereof typically the images may be reproductions of for example an airplane a boat a railway unit and an automobile chosen because of their distinct colorations and or shapes but as previously mentioned the areas of utilization of the improvement 10 are manifold as shown in fig2 through 6 the device 10 essentially comprises a mounting adapter ring 18 and an adjustable mask unit 20 removably and adjustably carried thereby ring 18 as appears in fig3 is a split type having opposed bosses 21 adjacent the split thereof and one of these bosses threadedly receives an allen type take up screw 22 spanning the split of the ring the ring 39 s internal diameter is substantially the same as the outer diameter of the lens housing flange 14 so that as applied peripherally to said flange the screw 22 may be taken up tightly to semi permanently mount the split image unit 10 on the camera 12 its removal is not contemplated but is of course readily and speedily accomplished if wished as appears in fig4 and 6 the mounting ring 18 is formed with an internal continuous circular groove 22 extending completely thereabout and the mask sub assembly or unit 20 carries as best shown in fig4 a pair of 180 u00b0 opposed detent balls 23 each biased inwardly by a small coil compression spring 24 for releasable engagement in the detent groove 22 the latter is interrupted at 90 u00b0 intervals by semi spherical ball seat indentations 25 and with these seats engaged by the detent.