Balance between heaven and earth
B+W graduated neutral density filters are often used in landscape photography in order to avoid an overexposure of the sky with a correct exposure of the ground. The filters are colored neutral gray on one half with a smooth transition into the neutral clear filter half. With threaded filters the rotatable mount allows an exact horizontal alignment.
The high-quality glass substrate of the B+W ND filters 701 and 702 is absolutely plano-parallel and finely polished. This guarantees for long lasting high optical quality versus easily scratchable plastic substrates. A B+W graduated ND filter is mainly used to compensate for a sky that is too bright compared to the dark foreground. For exposure metering, the camera or hand-held exposure meter should be pointed down towards the ground that is to have the correct exposure without the graduated filter. This almost always produces the ideal effect automatically.
Any increase in exposure to compensate for the absorption in the dense part of the graduated filter should be low so as not to weaken the filter effect too much!