SCHOTT - Neutral density filter, ND
Filters with a specific reduction of light in the visual spectrum range.
Neutral density filters of various light absorption levels are created with NG 11, NG 4 and NG 9 materials. The absorption level is carefully calibrated and controlled.
The thickness of the glass filter does vary and the typical thickness is outlined below.
Slight variations exist between batches so we compensate by adjusting the thickness of the material to match with the correct light transmission for the filter.
The reference wavelength for measurements is performed at 546nm.
Thickness |
Transmission |
Transmission (%) |
Glass type |
Typical thickness (mm) |
0,15 |
0,70 |
70,79 |
NG11 |
1,2 |
0,3 |
0,50 |
50,11 |
NG11 |
2,5 |
0,6 |
0,25 |
25,11 |
NG4 |
1,2 |
1,0 |
0,10 |
10,00 |
NG4 |
2,0 |
1,3 |
0,05 |
5,01 |
NG4 |
2,5 |
1,6 |
0,025 |
2,51 |
NG9 |
1,1 |
2,0 |
0,01 |
1,00 |
NG9 |
1,4 |
2,3 |
5x10-3 |
0,50 |
NG9 |
1,6 |
2,6 |
2,5x10-3 |
0,25 |
NG9 |
1,8 |
3,0 |
1x10-3 |
0,10 |
NG9 |
2,1 |
3,3 |
5x10-4 |
0,05 |
NG9 |
2,3 |
3,6 |
2,5x10-4 |
0,025 |
NG9 |
2,5 |
4,0 |
1x10-4 |
0,01 |
NG9 |
2,8 |
4,3 |
5x10-5 |
0,005 |
NG9 |
3,0 |
4,6 |
2,5x10-5 |
0,0025 |
NG9 |
3,2 |
5,0 |
1x10-5 |
0,001 |
NG9 |
3,5 |
| Standard neutral density filters | ||||
The thickness of the filters will vary based on the type of glass used and depending on the melt so that the final effect is a correct light transmission. Our production and polishing processes will maintain a tolerance of +/- 0.05mm in the thickness of the filters. As shown in table 3, the tolerances for thickness relate to the particular variations with the density and the light transmission.
Glass type |
OD (546nm) |
% (546nm) |
NG 11 |
+/- 0,006 |
+/-0,013 |
NG 4 |
+/- 0,03 |
+/- 0,06 |
NG 9 |
+/- 0,07 |
+/- 0,17 |
| variations of a thickness tolerance with +/-0,05 mm. | ||
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