HELIOPAN neutral gray filter ND 3.0 (1000x) E-77 Slim – 77 mm
A Heliopan gray filter (neutral density filter) reduces the amount of light that is absorbed by the lens. The color character is not affected. Heliopan gray filters are made of Schott glass and can be purchased in the following densities:
| density | Permeability | Extension factor | F-stop |
| ND 0.3 | 50.00% | 2x | -1 |
| ND 0.6 | 25.00% | 4x | -2 |
| ND 0.9 | 12.50% | 8x | -3 |
| ND 1.2 | 6.25% | 16x | -4 |
| ND 1.5 | 3.12% | 32x | -5 |
| ND 1.8 | 1.56% | 64x | -6 |
| ND 2.0 | 1.00% | 100x | -6.66 |
| ND 3.0 | 0.10% | 1000x | -10 |
Neutral gray filters (ND) are designated with logarithmic densities according to densitometric rules. What is relevant for photo users, however, is how many exposure levels (aperture or time levels) a filter reduces. The table above shows the corresponding values for easy determination.
Application example
Application example: For a “foamy” effect with water in a torrent, 1/250 s and aperture 8 are typical starting values. With an ND 2.0, the exposure time must be increased by 6 2/3 stops - practically up to about 1/2 s (1/250 → 1/125 → 1/60 → 1/30 → 1/15 → 1/8 → 1/4 → 1/2 s). Therefore an ND 2.0 is recommended here. Gray filters between ND 0.9 and ND 3.0 are sufficient for most photographic applications (except solar photography); A useful basic equipment would be e.g. B. ND 0.9, ND 2.0 and ND 3.0.
Creative tipCreative tip: For evening and night shots, close the aperture sharply, use a strong neutral density filter (e.g. ND 3.0) and use a tripod. Long-term shots blur people and create particularly surreal effects.