The old frog 15 red circle version looks better. Old Frog 15 has two versions, the red circle version and the blue circle version. The biggest difference is the number of diaphragm blades. The red circle lens with 14 aperture blade can shoot very beautiful 14-pin stars, which is really suitable for rigorous commercial photography. This excellent star-awning effect began to appear at the aperture F5.6. The blue circle version has five aperture blades, and the star awn of 10 needle is also very sharp and dazzling.