BTR GRADUATED ND filters have variable
throughout the filter space (soft transition from light to dark followed by
medium transition from dark to light). It means that the light entering the
camera is reduced gradually. This is very useful in situations when some parts
of the photograph are overexposed (the sky is too bright - especially at
sunsets and sunrises). BTR is perfect for scenes with rugged horizon. BTR
GRADUATED ND filters can be used in combination with full or graduated filters
in stacking mode.