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May 22, 2012, 03:19:48 AM


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Author Topic: How many stops on an ND filter?  (Read 348 times)

Offline Bosch232

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How many stops on an ND filter?
« on: February 15, 2012, 01:28:55 PM »
I have the Nifty Fifty.  I'd like to use it with shallow depth of field outside, but I don't own any filters yet.  What number of stops should I be considering?  I realize the real answer varies from shoot to shoot, but if I were going to buy one (or two) what would be a good starting range?

Also, it appears that the number behind "ND Number" isn't "Stops", but rather
2x = 1 stop
4x = 2 stops
8x = 3 stops
16x = 4 stops

Do I have this correct?
« Last Edit: February 15, 2012, 01:32:34 PM by Bosch232 »
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Offline Snapper

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Re: How many stops on an ND filter?
« Reply #1 on: February 15, 2012, 02:02:12 PM »
Forget 2 stops - a CPL will cover that if you already have one. If not, I would recommend you start there.
Have a look at variable ND filters such as this one: http://www.amazon.com/52mm-Fader-ND-Mark-II/dp/B003RDV7RW/ref=sr_1_fkmr1_1?ie=UTF8&qid=1329339589&sr=8-1-fkmr1
It costs a little more but will do the job of more than 1 filter without swapping them.

HTH

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Offline Bosch232

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Re: How many stops on an ND filter?
« Reply #2 on: February 15, 2012, 03:41:24 PM »
Yeah how do those work?  Do you rotate them and then just see what the meter is saying at any given position?
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Offline NightowlDVP

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Re: How many stops on an ND filter?
« Reply #3 on: February 15, 2012, 04:04:12 PM »
thats pretty much it, man.
i have a LCW fader nd on my nifty, and realistically, i dont think i could live without it.
it barely comes off the lens these days. (that could be because im lazy tho :) )
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Offline BlimpyB

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Re: How many stops on an ND filter?
« Reply #4 on: February 15, 2012, 06:55:08 PM »
A few points:

-Snapper, is there colour shift on that variable ND?  I haven't seen one for that cheap that's perfect, curious if you hit a good deal.

-52mm is a bit on the small side, I would highly recommend getting a larger one with step rings so you can use it on other lenses, especially if you're paying for a more expensive filter

-I haven't gotten deep enough into using them yet, but another alternative is to buy an absolute piece of crap set of ND filters for dirt cheap just to make sure you like them, then if so the $30 down the drain was a good research investment
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Offline Bif

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Re: How many stops on an ND filter?
« Reply #5 on: February 15, 2012, 07:15:32 PM »
Quote from: Bosch232 on February 15, 2012, 01:28:55 PM
I have the Nifty Fifty.  I'd like to use it with shallow depth of field outside, but I don't own any filters yet.  What number of stops should I be considering?  I realize the real answer varies from shoot to shoot, but if I were going to buy one (or two) what would be a good starting range?

Also, it appears that the number behind "ND Number" isn't "Stops", but rather
2x = 1 stop
4x = 2 stops
8x = 3 stops
16x = 4 stops

Do I have this correct?

.3 is one stop
.6 is two stops
.9 is three stops

It goes on from there somewhat.  What I do is carry 2 ND filters, a .6 and a .9 for two stop reduction and 3 stop reduction respectively.  "Stacking" them gives me a 5 stop reduction and those 3 values seem to be all I need.

I purchased Tiffen ND filters and that is the least expensive brand I would go, cheap ND filters often add a color cast.  Tiffen is a fairly good brand but even then with the two strengths "stacked" I do get a slight magenta cast.  Fairly easily correctable in post if it turns out noticeable.

I purchased them at first in 52mm size for the EF 50mm f1.8, and then in 58mm for the EF 24mm f2.8 and the EF 28mm f1.8 (those three are the main lenses I use for video).  What I could have done would have been to purchase them in 58mm only and with the 50mm lens use a 52-58mm stepup ring.
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Offline solid bob

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Re: How many stops on an ND filter?
« Reply #6 on: February 15, 2012, 08:17:25 PM »
I orderd a Tiffen ND from amazon for like $20-30. I use it primarily on my nifty50, so much so I keep my step-down ring own the filter constantly.
I have a .6 and it does the job really well and wouldnt get anything lower than a .6.
On the wiki page about ND filters there is a chart at the bottom that gives the different ratings and grades of light reduction. Some places will say ND4, 1/4, or .6, but it all means 2 stops down.
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Offline Snapper

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Re: How many stops on an ND filter?
« Reply #7 on: February 16, 2012, 01:15:20 PM »
This video (link posted by rpavich in another thread) shows how the variable ND filter works:
Light Craft Workshop Fader ND Filter


HTH
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Offline NightowlDVP

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Re: How many stops on an ND filter?
« Reply #8 on: February 16, 2012, 04:28:29 PM »
BIF-

Really good point about filter size mate. i have a LCW fader ND 52mm that i bought with my nifty, i also have a LCW 77mm to use with my tokina 11-16. I can use the latter with ALL of my lenses with stepping rings, but i can only use the 52mm on my nifty.
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