Filters: 2x stacked ND4 equals ND8? or ND16

[viix]

Curious. Does stacking 2 ND4 filters add up to ND8 or ND 16??
How about closeup filters? [+4] stacked above another [+4] = +8?

 

[megaweb]

ND16

.. same to ND8 + ND8 .. become ND64

 

[denizenx]

really? then +1 stack +4 == +4?
I thought the stops were powers of 2

 

[denizenx]

heh is there a +1?

 

[denizenx]

heh paiseh didn't know the numbers not in stops but in 2^stops...
;p

 

[viix]

OK.. I get it! thanx megaweb!

 

[Revo]

what if u stack say 4 n 2?? = 8? or something else???

 

[shawntim]

ND4 lets in 25% of the light.. ND2 lets in 50% of the light.

so when you stack 2x ND4, you get 25% of 25%, hence something similar to ND16.

 

[Revo]

Originally posted by shawntim
ND4 lets in 25% of the light.. ND2 lets in 50% of the light.

so when you stack 2x ND4, you get 25% of 25%, hence something similar to ND16.

Would that mean that if i were to stack ND4 n ND2

it would mean it would be 25% of 50% ?? assuming the ND2 is the filter on the top of ND4??

 

[shawntim]

Originally posted by Revo


Would that mean that if i were to stack ND4 n ND2

it would mean it would be 25% of 50% ?? assuming the ND2 is the filter on the top of ND4??

25% of 50% and 50% of 25% is the same thing right? so you'll let in only 12.5% of light which is the same as ND8 (100/8)