Introducing Triggertrap Mobile's ND Calculator


The newest addition to Triggertrap Mobile's collection of calculators makes working out your shutter speed when using an ND filter as easy as can be! Are you a big fan of long exposure photography? Keen to capture the perfect water smoothing photo? Then I'm sure you've heard of ND filters. They're a fantastic tool, but working out the perfect exposure when using an ND filter might leave you with a math-induced headache! Team Triggertrap decided we had experienced one headache too many, so put our thinking caps on and started working on a cure. The result is our shiny, new, super simple ND Calculator!

What the blazes is an ND filter?!

Neutral Density (ND) filters are totally neutral filters that don’t affect the colour of an image while they work like a pair of darkened sunglasses to darken the exposure by blocking some of the light entering the lens. This means you can use them to do longer exposures than normally possible, which is super useful for things like timelapses where you want to get a specific shutter speed without using a small aperture. This also allows you to slow your shutter speed down slightly, or use a wider aperture than would normally be possible.

There are two main types of ND filters. The most common are standard ND filters which come in different grades depending on how much light they prevent entering the camera. The range of filters goes from one stop to 10 stops. The other option, extremely popular with videographers, is to use a variable ND filter. Variable ND filters allow you adjust the density without taking the filters off. If you would like a more in depth explanation of ND filters, check out this great resource.

So, what is an ND calculator and how does it work?

Our ND calculator is here to work out your shutter speed change when you put a neutral density filter on the front of your lens. We’ve created this calculator to make things as easy as possible when you pop the filter on - no more guess work! Our ND calculator covers neutral density filters from 

1 to 10 stops in strength, and input shutter speeds from 1/8000th all the way to 30 seconds.

Here’s how to use the ND calculator:

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  1. Start with your neutral density filter off! Put your camera in aperture priority and compose your image.
  2. Take a test photograph. Check that the photo is looking good - nicely exposed with an aperture suitable for the scene.
  3. Take a note of the shutter speed, aperture and ISO settings from your test photo. These numbers will be the basis for your setup.
  4. Open up the ND Calculator, and select the shutter speed from your test photo on the Base Shutter Speed dial.
  5. Now select your ND filter strength on our calculator. If you’re using more than one ND filter, make sure you add them together!
  6. Attach your ND filter to your lens.
  7. Put your camera in manual mode, select the same aperture and ISO as used in your test frame and enter the shutter speed from the ND Calculator.

In some situations you will be getting shutter speeds longer than you enter in your camera. No problem! You can enter the time into our Timed Release mode with your camera set to Bulb to get the perfect result.

Perfect! Where can I find the ND Calculator?

The ND Calculator is available in Triggertrap Mobile for Android RIGHT NOW in our brand new Calculators section. The iOS version will be available very soon indeed, so stay tuned!

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