35mmdelux Posted February 13, 2007 Share Posted February 13, 2007 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 Link to comment Share on other sites More sharing options...
lilly_w Posted February 13, 2007 Share Posted February 13, 2007 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. Link to comment Share on other sites More sharing options...
lilly_w Posted February 13, 2007 Share Posted February 13, 2007 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. Link to comment Share on other sites More sharing options...
stephen_w. Posted February 13, 2007 Share Posted February 13, 2007 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. Link to comment Share on other sites More sharing options...
david_henderson Posted February 13, 2007 Share Posted February 13, 2007 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. Link to comment Share on other sites More sharing options...
frank_dzambic Posted February 13, 2007 Share Posted February 13, 2007 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. Link to comment Share on other sites More sharing options...
frank_dzambic Posted February 13, 2007 Share Posted February 13, 2007 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. Link to comment Share on other sites More sharing options...
frank_dzambic Posted February 13, 2007 Share Posted February 13, 2007 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. Link to comment Share on other sites More sharing options...
35mmdelux Posted February 14, 2007 Author Share Posted February 14, 2007 Thanks for your help everybody. Appreciate it - Paul Link to comment Share on other sites More sharing options...
aaron l Posted February 14, 2007 Share Posted February 14, 2007 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. Link to comment Share on other sites More sharing options...
35mmdelux Posted February 14, 2007 Author Share Posted February 14, 2007 Singh-Ray filters? Not B&W or Heliopan? thks. Link to comment Share on other sites More sharing options...
david_henderson Posted February 14, 2007 Share Posted February 14, 2007 Think someone might be reading "ND grad" and not just "ND". You'll be fine with B+W or Heliopan Link to comment Share on other sites More sharing options...
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