Spectra Effect Filter 72 - 49mm

The Spectra Effect filter produces a light spectrum (rainbow) on the bright areas of your image. The effect number defines the size of the rainbow.

You can find out the filter thread size of your lens by measuring the internal thread; it does not correspond at all to the focal length: for example, a 50mm f/1.8 lens can have a 49, 52, or 55mm thread...