Quick Tips: Live view exposure simulation and long exposures


Do you love using ND filters for long exposures? Do you have trouble calculating exposure times for scenes with ND filters? Here’s one trick I’d like to share that relies on your camera’s live view exposure simulation which can be used in conjunction or possibly even instead of an external app. These are some groundwork rules to know before using this technique:

  • Every doubling of ISO results in the sensor being more sensitive to one more ‘stop of light’.
  • Every doubling of shutter speed results in one more ‘stop of light’ let through to the sensor
  • (Every multiplication of 1.4 of aperture results in one ‘less stop light’ being let through to the sensor)
  • All of the above , in default DSLR settings, are three ‘clicks’ of a dial.
  • Long exposures tend to lead to noise , so try  to shoot with low iso  (iso100 would be ideal)

With these rules in mind, this is how I do a quick shutter speed calculation in the field.

  1. Compose your scene without the ND filter on and pay particular attention to using the desired aperture in your final shot to keep things as simple as possible.
  2. Place your ND filter on.
  3. Turn on live view (if you haven’t already) and set the shutter speed to 30 seconds.
  4. Bump the iso up until you have the correct exposure on live view
  5. Calculate your exposure time needed for correct exposure at low iso. For example, if iso200 was the correct exposure at 30 seconds, then a 1 minute exposure will  be needed at iso100. If iso800 was the correct exposure at 30 seconds, then a 4 minute exposure will be required at iso100. If iso 6400 was the correct exposure at 30 seconds, then a 32 minute exposure would be required (but I think at this level of darkness, the camera’s live view simulation would start to KO itself!)
  6. Take the shot .

Other considerations:

  1. If you are shooting at dawn, you  might need to factor in changing light during your exposure. I would shoot slightly SHORTER than the calculated exposure
  2. If you are shooting after dusk, you will need to factor in loss of light and I would shoot slightly LONGER than the calculated exposure

See the video below for an example of how quick this can work for you in the field, and the final image :

Video:

Remarkable Rocks ; Long exposure image shot at iso100, F11, 200 seconds.

Remarkable Rocks ; Long exposure image shot at iso100, F11, 200 seconds.

 

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Posted on May 24, 2016, in Australia, How we..., Photography, South Australia and tagged , , , , , , , , , , , , , , , . Bookmark the permalink. 4 Comments.

  1. Clear and simple idea! Thanks Dylan.

  2. is this the one you used?
    NiSi Nano IR Neutral Density Filter ND1000 (3.0) 10 Stop? .If so, how much it is if
    i purchase through you Thanks

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