TS-Optics 1.25" Grey Filter ND03 - 50% Transmission
This neutral density filter or grey filter reduces the image brightness to half of the original value without colouring the image. Thus haze effects on moon and planets and also at daytime observation are avoided. The filter is also suitable for observing double stars with one particularly bright component. We recommend the filter for smaller telescopes up to 70 mm aperture.
The adaptation:
The filter is just screwed to the 1.25" filter thread of the eyepiece or adapter. With transition adapters, the filter can also be screwed in front of a camera lens (see recommended accessories).
What does the ND value mean:
The ND value provides information about the attenuation factor. The higher the value, the stronger the attenuation factor. However, there are two versions:
1. Logarithmic scaleThis is used with our older gray filters, but also for solar filter foil. The transmission is calculated here as 1/10
ND, whereby the ND value may have to be provided with a comma:
♦ ND03 - the light is reduced to 1/10
0.3 times, i.e. 1/2 (transmission 50%)
♦ ND06 - the light is reduced to 1/10
0.6 times, i.e. 1/4 (transmission 25%)
♦ ND09 - the light is reduced to 1/10
0.9 times, i.e. 1/8 (transmission 12.5%)
Advantages are the large range and the possibility to easily add the ND values of combined filters.
2. Linear scaleThis is used with our newer gray filters. The transmission is simply calculated according to 1/ND:
♦ ND16 - reduction by 16 times - light transmission is 6.25%
♦ ND32 - reduction by 32 times - light transmission is 3.13%
♦ ND64 - reduction by 64 times - light transmission is 1.56%
The advantages are the simple calculation of the attenuation by individual filters and thus the direct calculation of the extension of exposure times.
Practical tip from Teleskop-Service:
Due to filter threads on both sides, you can combine the grey filter with 1.25" colour filters, thus you can achieve an increase in contrast and a reduction of brightness.
You can also screw two grey filters together, thus adjusting the damping effect even better.
