B+W Gray Filters 101 and 102
The gray filter series begins with low light attenuation. Type 101 reduces the light by exactly one f-stop (filter factor 2x), type 102 by two f-stops (filter factor 4x). The moderate extension of the exposure values is recommended for indoors or outdoor shots with little light. At lower shutter speeds, creative soft focus effects, wipe effects and flowing effects for waterfalls can be achieved. Opening the
aperture allows selective focus instead of deep focus – a desired effect when filming videos with DSLRs.