Exposure Calculator

Exposure Calculator is an app that I developed to calculate the shutter time required for taking long exposures when using an ND (Neutral Density) filter.

To use:

• first expose your scene as you would normally, without an ND filter mounted
• note the shutter speed required for a properly exposed photo
• set this shutter speed value into the first window of the app
• now select the ND filter density that you would like to use
• you will see that the third window will display the new shutter speed for you to use when the ND filter is mounted
• for exposures longer than 4 seconds you will have the ability to launch a popup timer to help you keep track of your exposure time

Tip: If you are using a really dark ND filter, such as an ND1000, your camera will not be able to focus when you release the shutter. To get around this, first focus on the scene without the ND filter, then switch your camera into manual focus, then mount the ND filter. Your camera will use the current set focus and not try to refocus.

The app also includes two other calculators, one to calculate the full frame equivalent of a lens on a crop sensor body, and the second to calculate the full frame equivalent of an aperture (f-stop) on a crop sensor body.