This is the froggy mating season, and they have been at it in my garden pond
I don't have a proper macro lens, and the only extension tubes in my possession are M42 screw thread, so my solution is to use an elderly Takumar 135mm f 3.5 lens along with an 11 mm extension tube.
Click for a bigger image.
Not bad for a lens maybe 45 years old! This is the M42 Super Multi Coated version, in production from 1971-1975.
Sony NEX 6