-High quality solid brass rings. -Black anodized rings with stops at both ends of the ND range. -ND variable from 1 to 6.6 stops. -Color neutral regardless of ND value. -Calibrated, repeatable settings.
The Heliopan 67mm Variable Grey Neutral Density Glass Filter ( 1-6 Stops) 705890 can reduce the exposure on your camera anywhere from 1.0 to 6.6 f/stops. When shooting with high ISOs, this filter can allow you to shoot under bright lighting conditions like on a snowy mountain or at the beach. This is also an ideal filter for creating long exposure special effects such as capturing the "blur" of running water. It also permits you to control your depth of field by helping isolate your subject from its background by using a wider aperture. A convenient index scale on the filter ring makes exposures repeatable and exact.
This is the construction of a type of filter. The type of process used to create a filter can affect its price. Filters can be constructed out of regular glass that sandwiches a coloured gel in between or in high-end filters, raw elements are added to the molten optical glass so there is no risk of uneven colour or fading.
1-stop = 50% light loss 2-stop = 25% light loss 3-stop = 12.50% light loss 4-stop = 6.25% light loss 5-stop = 3.12% light loss 6-stop = 1.6% light loss
When placed in the optical path, many filters block a certain amount of light from reaching the lens. Filter factor relates to how much exposure compensation is required in order to adjust for this. Most cameras have TTL metering and will be able to do this automatically.