The Soft FX 3 provides a much more pronounced softening effect than the 1. While the 1 is subtle, the 3 is used for a more stylized, 'dreamy' look with visible highlight blooming.
It softens fine details like pores and wrinkles but is designed to maintain the structural integrity and contrast of the overall image.
No, the Tiffen Soft FX 3 has a negligible filter factor and does not require exposure compensation.