Neutral Density (NDs) - Requesting Help

Hi All,

 

If I'm shooting at 1/1000 at f/16 (400iso), what ND filter would I need to cut

it back where my aperture would read f/4.0 or f/5.6 and my speed would read

1/250-1/500 maximum?

 

Can this same filter be used in B&W AND in colour emulions?

 

Thanks alot - Paul

f16 to f4 = 4 stops. 1/1000 to 1/250 = 2 stops. You'll need a 6-stop ND. You might also consider stacking a 2-stop onto a 3-stop as they may prove more versatile when used alone. Vignetting may occur with stacking.

PS - ND filters are perfectly useful w/ both color and b/w. Only the intensity of the light is changing, provided one is using a first-rate filter without a colorcast.

C'mon Paul, you should know how to figure filter factors. It's aperture I'd want to optimize, not speed. I'd still want the maximum speed as possible when choosing a ND, for example, I might want to use 1.4/2 in daylight with 400ISO at 1/1000 (why not?). I'd get a ND 3 for eight stops. But, why would I use 400 in daylight? I have been caught with that combo when my intention to shoot inside a Toledo, Spain Cathedral when I found a group of girls doing street photos of themselves (now deleted) outside.

Couple of points. First be careful using strong nd filters with colour film. I have a Hoya 8x ( 3 stop) ND filter that has an olive cast strong enough to render any colour film very strangely.

 

When you combine nd filters you need to add rather than multiply the strengths. So a 3 stop and a 2 stop would reduce light by five stops not 6. The first poster may well know this very well, and is probably suggesting a 2 and a 3 stop in the interests of versatility, but its important you know that 2+3 =5. However the power of each filter may (as in the above example ) be expressed in terms of its power to cut out light. So a 8x (3 stop) filter and a 4x (2 stop) filter when used together can be described as 8x4 =32X . But 32x and five stops are the same. I hope that's clear.

1/1000 @f/16 is the equivalent of 1/8000th at f/5.6, or 1/16,000th at f/4.

 

So if you wanted to shoot at f/5.6, a 4 stop ND filter would give you 1/500th and a 5 stop ND filter would get you 1/250th.

 

If you wanted to shoot at f/4, a 5 stop ND filter would give you 1/500th, and a 6 stop ND filter would give you 1/250th.

I think Lilly failed to consider an equivalent exposure when doing her calculations, and it almost appeared to be a trick question at first. The original poster wants to use a shutter speed that's 1-2 stops slower, and an f/stop that's 3-4 stops slower, so you have to account for the discrepancy.

I mis-spoke. The original poster wants to use a shutter speed that's 1-2 stops slower, and an f/stop that's 3-4 stops FASTER. So you have to account for the discrepancy.

Thanks for your help everybody. Appreciate it - Paul

Get Singh-Ray filters. They don't induce a color cast. Yes, you can use these filtes with color and b&w.

 

What is your foreground vs background exposure? You need to cut down 3-4 stops just based on your numbers.

Singh-Ray filters? Not B&W or Heliopan?

 

thks.

Think someone might be reading "ND grad" and not just "ND". You'll be fine with B+W or Heliopan