Stacking ND4s

Ricky

Ricky

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Ricky
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I got 2 ND4 filters and planning to get 2 more and I wonder if I stack them all togetner then how many stop would it become?
 
I wished I had more than one today. As dull as it was I couldn't get more than 8 seconds even at f/22, ISO 100. I'd worry more about colour casts than how many stops though, unless they are all high end ones? Otherwise, I imagine the stops add up ... someone with actual knowledge will no doubt correct me on that.
 
I could be way off the mark and it's been a while since I messed about with multiple filters but from memory:

ND4 = 2 stop / 25% (0.6 density)
ND8 = 3 stop / 12.5% (0.9 density)

So 2 X ND4 does not = ND8

One ND4 = 25% light = 2 stop
Add a 2nd ND4 on top = 25% of 25% = 6.25%. = ND16 = 4 stop
Add a 3rd ND4 then it's 25% of 6.25% = 1.5625% = ND64 = 6 stop
Add a 4th ND4 then it's 25% of 1.5625% = 0.391% which is ND256 = 8 stop

Stacking like that - you might be better off investing in individual ND filters rather than having 4 the same.
 
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I have to admit I'm a complete n00b when it comes to filters, in general. I bought the ND 4, which was pricey enough, and thought I was getting 4 stops. Turns out it's only 2. Bah, the trickery!
 
It is a bit misleading

Simple terms:

ND2 = 1 stop = 50% light
ND4 = 2 stop = 25% light
ND8 = 3 stop = 12.5% light

and so on......

Just think about each ND step (as they double) as halving the light - if used on their own that is.

ND1024 = what people refer to as a 10 stop filter which is just less than 0.1% light
 
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A 10 stop would be brill, if I had anywhere decent to make use of it. Best I could find today was a bit of fast water along the river Boyne:


Stormy moment along the river Boyne, Meath by Cagey75, on Flickr

Maxed out everything, the F stop at 22, the ISO, well, I think I had another fake option to go to 50, the ND 4 on, no tripod but rested the cam on a bridge ... best I could get, 6 seconds.
 
Small world Cagey (nice shot) my brother and his family live just outside Oldcastle (Lakefield) so I'm often around the Meath area.
 
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Ha, there you go. I'm a n00b in Meath, well, living up here 3 year [missus is from here] Still finding my way around. Originally from further down south, Carlow. Next time you're around feel free to give me a shout ;)
 
Cagey75 said:
Ha, there you go. I'm a n00b in Meath, well, living up here 3 year [missus is from here] Still finding my way around. Originally from further down south, Carlow. Next time you're around feel free to give me a shout ;)
Click to expand...

He was gamekeeper at Dunsaney Castle before moving out to live in the lodge at Loughcrew House and now has a family at Lakefield. I'm sure your missus knows the places and possibly his wife's family.:lol:

Anyway - better not trash the thread.
 
Not sure of those areas, but she probably would know

And aye, ND filters , stacked ...

;)
 
Thanks everyone! I got 2 of the jacobs ND filters from ebay. But it seem to make sence to pay more for a 10 stopper.
 
Ricky said:
Thanks everyone! I got 2 of the jacobs ND filters from ebay. But it seem to make sence to pay more for a 10 stopper.
Click to expand...

Check out the thread about using Welding Glass as a cheap alternative.

It's a bit 'Heath Robinson' but some great results can be had for a couple of quid.
 
dinners said:
I could be way off the mark and it's been a while since I messed about with multiple filters but from memory:

ND4 = 2 stop / 25% (0.6 density)
ND8 = 3 stop / 12.5% (0.9 density)

So 2 X ND4 does not = ND8

One ND4 = 25% light = 2 stop
Add a 2nd ND4 on top = 25% of 25% = 6.25%. = ND16 = 4 stop
Add a 3rd ND4 then it's 25% of 6.25% = 1.5625% = ND64 = 6 stop
Add a 4th ND4 then it's 25% of 1.5625% = 0.391% which is ND256 = 8 stop

Stacking like that - you might be better off investing in individual ND filters rather than having 4 the same.
Click to expand...

Stacking multiple filters means multiple glass surfaces and a thicker total amount of glass. Logic suggests that increases the chances of degrading the image.
Don't know why they cannot just label these filters according to the number of stops they represent.:bonk:
 
I think different manufacturers do adopt some different naming conventions.
 
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