Wednesday, September 5, 2012

NDx400–Long exposures in broad daylight “How-to” guide

Finally after a long long wait I got my ND filter, the NDx400. Question is why do you need it and here are the answers;

  • NDx400 is Neutral Density filter with an ability give you –9EV (minus 9 stop) advantage while shooting.
  • What does that mean? It means it will allow you to use very slow shutter speed even in broad daylight, which otherwise will not be possible even with smallest aperture (f/22).
  • This means, you can shoot a velvety waterfall in daylight if you like for instance

Here is an example.

WITOUT NDx400 and CPL:

I shot this scene at around 9 AM bright overcast conditions

F/11, 1/200, ISO200 (Saturation and contrast slightly adjusted in CS4)

OLYMPUS DIGITAL CAMERA

Notice the sky, looks dirty with the clouds. Picture is not too appealing overall and looks boring.

WITH NDx400 + CPL: CPL=Circular Polarizer. I used it because it was already attached to my lens. I attached NDx400 on the CPL. This is called filter stacking. Beware – Filter stacking will give you vignetting  i.e. one or more dark corners in your pics. It gave me one, which I removed in Photoshop. Filter stacking is NOT recommended, unless you know what you are doing and you know how to remove vignetting in PP)

Time around 9AM with bright overcast sky.
OM-D with 12-50 12MM
NDx400 + CPL
F/22, 30s, ISO200, IS Off, Anti Shock ON, Noise Reduction ON, Noise Filter HIGH
Only Contrast and saturation adjusted in CS4

OLYMPUS DIGITAL CAMERA

Notice how the ordinary mundane scene has changed with silky and velvety background, making the structure standout as if in  3-D .

The Trick

But its not simple to use NDx400 as if it were a CPL filter. When you attach the NDx400 to your lens, you will find that your camera will, in best case, struggle to focus OR in worst case - which is more often than not - will refuse to focus. The reason? its the reduction of light which the NDx400 causes. By using NDx400 you are reducing the light intensity to less than 1/500th of the original intensity. So its very dark when you see through the lens.

So in order to use the NDx400 properly, you need to do a little trickery to make it work. And here is how to do it

  • Set the camera on tripod. Make sure the Anti-Shock (mirror lockup) is on and In body and In Lens stabilizers (IS/OIS etc) are OFF
  • Set the ISO @ 200 or any value you need. Make sure this constant throughout.
  • Set the camera in the aperture priority mode (A/Av mode using the dial). Set the aperture to, lets say, f/11 for the landscape shooting.
  • Focus the camera on the scene and press the shutter half way. Note down the shutter speed. Lets say it gives you the reading 1/60s
  • Now set the camera to Manual Focus WITHOUT CHANGING other settings like aperture and focal length of the lens.
  • Change the dial to full Manual Mode (M) from Aperture Priority mode. Attach the NDx400 filter on the lens
  • Ensure that your Aperture is still at f/11 as set above. Now change the shutter speed to –9EV (minus 9 stops) of what you noted above. Original shutter speed without NDx400 was 1/60s, so with NDx400 filter you need to step –9EV down which will give you 8secs.
  • You are all set, press the shutter and see the result. If its underexposed, then reduce the shutter speed further, if its overexposed then you can reduce the aperture to maybe f/16 if you want to keep same shutter.

I know its a bit of a hardwork, but your results will be priceless!

Hope you get inspired!

CIAO!

Love

Puru