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04/01/2011 05:58:57 PM · #1 |
I have some questions about ND filters.
1. I have an ND2, how many stops of light reduction is that? Someone told me they thought it was 1 stop.
2. What would be the value of just 1 stop reduction? Where would you use that?
3. What is the maximum reduction of any ND filters? ie, how many stops of light.
Any other info on ND would be appreciated.
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04/01/2011 06:05:54 PM · #2 |
What brand of ND filter do you have? Chances are, the ND2 is a one stop filter and it would be used in any situation where you needed to double the length of your shutter speed. Most ND filters come in 1, 2, and 3 stop sets.
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04/01/2011 06:11:26 PM · #3 |
1). ND2 is a one stop reduction, ie. 1/2 the light passes through it. 1 stop down = 1/2 light. ND4 would be 2 stops 1/2 of 1/2 (or 1/4) the amount of light. ND8 = 1/8 the amount of light or 3 stops, etc, etc...
2). The value in one stop reduction? Well, especially at long focal lengths, the difference between f/8 and f/5.6 could be a significant narrowing of DoF. For shutter speeds, there can be a significant increase in blur between 1/25 and 1/60seconds, especially for fast moving objects.
3). Theoretically there is not upper limit on how many stops that a ND filter could go, since each cuts light by 1/2, you can cut light in half for infinitely amount of times.
However, these are considered extreme ND filters... Hoya 9-stop ND x400 Filter, the Lee “Big Stopper” 10-stop ND Filter, and the 10-stop B+W #110 ND Filter
Message edited by author 2011-04-01 18:17:13.
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04/01/2011 08:53:02 PM · #4 |
Just a tip from another thread, I have verified experimentally that a circular polarizer and a linear polarizer can be stacked and aligned in relation to each other to achieve variable opacity to nearly opaque. As such they can (probably) be used as a variable ND filter to achieve almost any desired combination of aperture and shutter-speed. These were taken with a mini-tripod at a pretty long focal length, so they have a bit of camera-shake ... :-(
f/8, 2-second exposure  f/8, 4-second exposure (unadjusted)  |
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04/01/2011 09:41:22 PM · #5 |
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04/01/2011 09:48:10 PM · #6 |
The ultimate use of ND filters is to make a city empty, to so extend an exposure that all the people and cars are no longer visible. Empty LA Empty Tokyo
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04/01/2011 11:38:18 PM · #7 |
Originally posted by alohadave:
You do need to be careful though with the filters you use. The ones have when you get to the maximum filtering, a strong blue color cast appears. I've taken to converting them to B&W. |
I noticed it was possible to get a pronounced blue cast, but it seemed to go away when I rotated the two filters together. I suspect this may have affected the overall polarization effect, but the ND filtering should come only from the relationship of the two filters to each other, and not to the orientation of one or the other to the sun or scene. |
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04/02/2011 03:12:19 PM · #8 |
Originally posted by GeneralE:
Originally posted by alohadave:
You do need to be careful though with the filters you use. The ones have when you get to the maximum filtering, a strong blue color cast appears. I've taken to converting them to B&W. |
I noticed it was possible to get a pronounced blue cast, but it seemed to go away when I rotated the two filters together. I suspect this may have affected the overall polarization effect, but the ND filtering should come only from the relationship of the two filters to each other, and not to the orientation of one or the other to the sun or scene. |
Yes, it's totally their relationship to each other from what I've seen.
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04/02/2011 03:55:02 PM · #9 |
While stacking any number of polarizing filters will decrease the light the sensor sees, they reason for buying neutral density filters is that they are color neutral, and will preserve the color balance.
A while ago on a GTG I saw  jdannels using a graduated ND filter which I hadn't seen before. I picked one up and now use it quite often, more than any solid ND. |
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04/03/2011 02:39:08 PM · #10 |
Originally posted by BrennanOB:
While stacking any number of polarizing filters will decrease the light the sensor sees, they reason for buying neutral density filters is that they are color neutral, and will preserve the color balance. |
I thought (from my sample shots) that I was able to get a relatively neutral color balance. They were shot with the Auto-WB setting, the first has a moderate exposure and color adjustment using RGB and Blue/Yellow Curves, the second is unadjusted.
I just made some tests to try and "calibrate" the two polarizers ... it seems I can get up to four stops of filtration. It takes a significant twist to get to the first (one stop) setting, but after that it is very sensitive to slight twists, with the next three stops only about 3-4mm apart on the rim of my 58mm diameter filters.
Originally posted by BrennanOB:
A while ago on a GTG I saw jdannels using a graduated ND filter which I hadn't seen before. I picked one up and now use it quite often, more than any solid ND. |
I have one of those as well, though I rarely get around to using it. It is usually used to balance out a bright sky and dark foreground. |
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