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Neutral density filters of various light absorption levels are created with NG4, NG9 and NG11 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 and this is compensated for by adjusting the thickness of the material to match the correct light transmission for the filter. The reference wavelength for measurements is performed at 546nm.

Standard neutral density filters

Density Transmission Transmission (%) Type Typical Thickness (mm)    
0,15 0,70 70,79 NG11 1,2    
0,3 0,5 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    

ND filters can be produced for any specific wavelength and any level of transmission. We normally hold 50x50mm filters on stock. Custom sizes can be delivered upon request. A set of all 16 different ND filters is available along with an optional protective wooden box.

Please contact us with your individual requirements.



In order to archive specific transmission properties, the thickness of the filters will vary based on the type of glass used and the melt. Our production and polishing processes ensure a tolerance of ± 0.05mm in the thickness of the filters. As shown in table mentioned below, the tolerances for thickness relate to variations of the density and therefore light transmission of the glass.

Type OD (546nm) % (546nm)  
NG11 +/-0,006 +/-0,013  
NG4 +/-0,03 +/-0,06  
NG9 +/-0,07 +/-0,17  
Deviation with a thickness tolerance of +/-0,05 mm      

Please do not hesitate to contact us. We are ready to offer you assistance.

For further information about the desired filters please take notice of the current SCHOTT data sheet / catalogue.