how many stops is .6 ND filter?

[ToddB]

Hey guys,

Co-worker let me borrow a ND filter. it says .6 on the ring. How many stops is that?

Todd

 

[Ken Nadvornick]

That's a 2-stop reduction.

0.3 = 1-stop
0.6 = 2-stop
0.9 = 3-stop

And so on...

Ken

 

[Trail Images]

Todd, most vendors rate the .6 at 2 stops.

I now see Ken has the 3 standard sizes in his list......

 

[Kawaiithulhu]

If you're curious about why, those are in log-2 notation.

2 log 2 = 0.602
3 log 2 = 0.903

 

[polyglot]

Actually, they are log-base-10, or "D". A 1.0D has 10x attenuation, a 2.0D has 100x attenuation, an nD is 10n; in this case 0.6D = 100.6 = 3.98x. Stops are log-2, i.e. 4 stops is 24 = 16x attenuation.

To convert from D to stops, you do this:

stops = log2(10D)
stops = D / log10(2) = D / 0.301

in this case, stops = 0.6 / 0.301 = 1.993 = 2 stops. This is what you'd expect from above, because 3.98x attenuation is pretty much 4x, and 4x is 2 stops.

 

[ToddB]

Thanks guys, I have it on my F4, so I'm assuming camera metering will auto compensate for the filter?

 

[AgX]

Then just a quick use of that meter would have given you that answer without any math...

 

[RalphLambrecht]

every 0.3 equal 1 stop,because the log of 2 is roughly 0.3;photomath is soo much fun.I wish they would have used it in highschool;then,i'm sure I would have paid much better attention.

 

[Pioneer]

every 0.3 equal 1 stop,because the log of 2 is roughly 0.3;photomath is soo much fun.I wish they would have used it in highschool;then,i'm sure I would have paid much better attention.

What!! Did someone say math??

Groan...not again.

 

[blaine.minazzi]

Thar's 3 kinds of people on this world. Thems that kin do math, and thems that cain't.

 

[BrianShaw]

Thanks guys, I have it on my F4, so I'm assuming camera metering will auto compensate for the filter?

That's a good assumption.

 

[John Koehrer]

Thar's 3 kinds of people on this world. Thems that kin do math, and thems that cain't.

The math is good but the American English is wrong.

It should read: Thems whut kin do math and thems whut cain't

 

[Jim Noel]

Hey guys,

Co-worker let me borrow a ND filter. it says .6 on the ring. How many stops is that?

Todd

Two

 

[RalphLambrecht]

That's a good assumption.

itwill

 

[wildbill]

Wow