ND Filters

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thanos_tj's

New member
Can I ask something,what's the difference between an ND 2,4,8,16 filter and an ND 400 ? I found an adjustable filter ND2 to ND400.What does this mean ?

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480sparky

Senior Member
ND2 = 1 stop less light
ND4 = 2 stops less light
ND8 = 3 stops less light
ND16 = 4 stops less light.

ND2 to ND400 = variable, 1-8.667 stops less light.
 
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STM

Senior Member
Since things in photography work to the power of two (twice or half as much light per f/stop) you can use the exponent as the number of stops when referring to ND filters 2[SUP]1[/SUP]=2, 2[SUP]2[/SUP]=4, 2[SUP]3[/SUP]=8, 2[SUP]4[/SUP]=16 and so forth
 
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480sparky

Senior Member
STM said:
Since things in photography work to the power of two (twice or half as much light per f/stop) you can use the exponent as the number of stops when referring to ND filters 2[SUP]1[/SUP]=2, 2[SUP]2[/SUP]=4, 2[SUP]3[/SUP]=8, 2[SUP]4[/SUP]=16 and so forth
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If you're using the NDnotation number. If you're using the ND.notation (ND.03, ND.06, ND1.2 etc) or ND1notation (ND101, ND102 etc) that convention won't work.
 
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STM

Senior Member
480sparky said:
If you're using the NDnotation number. If you're using the ND.notation (ND.03, ND.06, ND1.2 etc) or ND1notation (ND101, ND102 etc) that convention won't work.
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Where is that nomenclature used? I have never seen it annotated that way and my answer was written with the OP's question in mind, which quoted the same nomenclature to which I was referring.
 
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Horoscope Fish

Horoscope Fish

Senior Member
STM said:
Where is that nomenclature used? I have never seen it annotated that way and my answer was written with the OP's question in mind, which quoted the same nomenclature to which I was referring.
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The only time I've run into someone wanting/needing to speak in terms of optical density was when I had to speak to a "factory rep" (read: engineer) at... I want to say Heliopan, but I'm unclear on the details; it was a long time ago.
...
 
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STM

Senior Member
Horoscope Fish said:
The only time I've run into someone wanting/needing to speak in terms of optical density was when I had to speak to a "factory rep" (read: engineer) at... I want to say Heliopan, but I'm unclear on the details; it was a long time ago.
...
Click to expand...

It is certainly not practical for photographers in everyday use. The only time I deal with OD is in the darkroom doing work with color filtration.
 
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480sparky

Senior Member
STM said:
Where is that nomenclature used? I have never seen it annotated that way and my answer was written with the OP's question in mind, which quoted the same nomenclature to which I was referring.
Click to expand...

Different manufacturers use the different numbering conventions.Tiffen, for example, uses the ND. system.
 
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