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Time-lapse and Long Exposure Control With Your Smartphone

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This post is part of a series called Time-Lapse and Long Exposure.
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Most entry and mid-level digital cameras don't offer shutter speed’s longer than 30 seconds or have built in intervalometers. This makes it difficult to explore some interesting areas of photography, like long exposure shooting and timelapse photography.

There is, however, an everyday device that can give your these abilities: your smartphone. Connecting your smartphone and camera used to be a painful experience but with the TriggerTrap mobile dongle and the free TriggerTrap app (available for both iOS and Android) it’s simple. Install the app, and you'll be able to use your smartphone’s brains to play with your camera with a whole new range of creative opportunities.

The TriggerTrap Mobile Dongle

The TriggerTrap mobile dongle is the device that lets your phone interact with your camera. It connects to your phone through the 3.5mm headphone jack and your camera through its cable release connection. The majority of modern DSLRs and mirrorless cameras from major brands are supported. The dongle is the same for all cameras, but the cable that connects them is different.

Use the TriggerTrap website to ensure that your camera is supported and which connector cable to buy.

triggertrap set up
The TriggerTrap set up. Image by TriggerTrap.

The TriggerTrap App

The TriggerTrap app is available for free in the iOS and Android app stores. To use the TriggerTrap mobile dongle with your camera you’ll need the app.

triggertrap app
The TriggerTrap app.

Camera Settings

Before doing anything with TriggerTrap, you need to set your camera up. TrigerTrap requires that your camera be in manual focus mode. Either focus the shot using autofocus and then switch your camera to manual focus, or just focus manually.

Aperture and ISO are always set, as normal, on your camera. Depending on what TriggerTrap mode you are using, you may need to set the shutter speed on your camera, or else to set your camera to Bulb and use TriggerTrap to set the exposure time.

As a general rule, if you are taking a long exposure shot your camera needs to be in bulb and you set the shutter speed using TriggerTrap; if you are taking a timelapse, you set the shutter speed on your camera.

Cable Release and Long Exposure

At its most basic, the TriggerTrap app and dongle let you use your phone to trigger your camera. The simplest example of this is the app’s cable release modes.

If you are shooting with a tripod, and especially if you’re shooting with a slow shutter speed, you should use some sort of cable release. Even if your shutter speed is 1/30s or faster, pressing the shutter button on your camera can cause it to shake and introduce blur to your images. Cable releases, or TriggerTrap and your phone, stop you from physically touching your camera and so keep your images sharp.

The TriggerTrap app has four basic cable release modes: Simple Cable Release, Press and Hold, Press and Lock and Timed Release. For all but the Simple Cable Release mode you need to set your camera’s shutter speed to Bulb.

Taking the Shot

For long exposure photography, the fourth mode — Timed Release — is the most useful. Long exposure is one of my favourite areas of photography. It’s a creatively rich style; you are no longer capturing exactly what you see but, instead, what a place feels like. You can also use it to shoot in extremely low light situations.

To take a long exposure shot you need your camera on a tripod. Connect your camera to your phone with the TriggerTrap dongle. Turn the volume on your phone up to its maximum, open the TriggerTrap app and select Timed Release from the menu.

To find my framing, shutter speed and focus, I like to use a series of high-ISO and wide-aperture test shots. Generally, for long exposures I use an aperture of f/16 for the final shot. This aperture is small enough to reduce light, and is the sharpest aperture in my lens. If I want an even longer exposure, I add a neutral density filter, which reduces the amount of light that can reach the sensor.

For the shot below, I tested my composition and exposure with a shutter speed of 1/30 of a second at f/2.8. From the test, I calculated that my shutter speed at f/16 would be 30 seconds. Then I added a 3-stop neutral density filter, making the final shot’s shutter speed 240 seconds, or four minutes.

Once you’ve found the shutter speed for your final shot, enter it into the TriggerTrap app, step back and push the red button.

triggertrap long exposure
Long exposure taken with TriggerTrap mobile dongle. Photo by Harry Guinness.

TriggerTrap's Time-lapse Intervalometer

 It’s possible to get reasonably long exposures with your camera without any extra equipment. To get time-lapse videos, you need an intervalometer. Some professional cameras come with one built in. The majority of consumer cameras do not. Time-lapse photography is where the TriggerTrap app and dongle come into their own.

Like with long exposures, time-lapse photography adds an extra dimension to your images: time. While a long exposure takes a long period of time and condenses it into a single instant, a time-lapse takes a long period of time and condenses it into a shorter period.

The TriggerTrap app has five different timelapse modes: Timelapse, TimeWarp, DistanceLapse, StarTrail and Bramping.

Timelapse is the most basic and simply triggers your camera repeatedly after a set time interval until you stop it.

TimeWarp is the same except the interval changes throughout the timelapse; with this you can include acceleration or deceleration in your timelapses.

DistanceLapse uses your phone’s GPS to trigger once you’ve covered a set distance; if you want to get a timelapse of a road trip without lots of traffic shots, this is the way to do it.

StarTrail combines TriggerTrap’s long exposure features with its timelapse features.

Finally, Bramping—or bulb ramping—allows you to take a timelapse but adjust the shutter speed throughout; if you are taking a timelapse of sunrise or sunset you use this to adapt for the changing light.

Taking the Shot

To take a simple timelapse with TriggerTrap and your camera, set everything up as you did for the long exposure shot: you need your camera on a tripod with the TriggerTrap dongle connecting your phone.

I use a series of test shots to find my exposure settings and focus. As with long exposures, I tend to work with an aperture of f/16. Once you’ve found your exposure settings, decide how long you want the resulting movie to be. The most common video frame rates are 24 and 30 frames per second. You will, thus, need 24 or 30 image for every second of video. For example, if you are condensing an hour long event into a 90 second, 24fps, timelapse video, you need 2160 images; one every 1.667 seconds.

In the Timelapse mode, enter the interval value. When you’re ready, press the red button and leave your camera run for as long as it needs.

There are many ways to turn the resulting series of images into a video. My fellow Tuts+ author Stefan has written a great tutorial that shows how to do it with iMovie. Below is a short example I made, watch it in HD and full-screen to get the full effect.

Tip: High Definition video is at a far lower resolution than what your camera can shoot. I generally nail my exposure in camera and then switch my image format to JPEG to save space and make processing the files easier.

Additional Triggers

So far, I’ve only touched on what you can do with TriggerTrap. There are many other creative things you can do with the set up. Sensor Modes that leverage your phone’s abilities to detect sound, vibration, motion or faces to trigger your camera.

You can also connect two devices running the TriggerTrap app on the same WiFi network. You connect one device to your camera and put it in WiFi Slave Mode and use a second device—perhaps an iPad or other tablet—as a WiFi Master to trigger the camera using any of the regular TriggerTrap modes. This is great if you’re interested in exploring remote photography.


In this tutorial I’ve introduced you to the TriggerTrap mobile dongle and shown you how you can use it to connect your smartphone and camera so you can get started with long exposure and timelapse photography. While it may not be the most sophisticated tool, the TriggerTrap set up is great way to expand your creativity by trying new areas of photography without breaking the bank.

Many of the features that TriggerTrap brings to the table are available in high-end camera bodies, or with additional accessories. If you are extremely serious about a particular photographic niche, the specialised tools will give you the best results. For most photographers though, a modern phone and a 30 dollar connector is an affordable introduction to the worlds of long exposure and timelapse photography.

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