Take Long Exposure Photos

Now we come to the fun part of making art that can hover in space! You'll freeze temporal, sequential art into what appears to be a single instant! How is this done? The trick is long exposure photography.

Typically, we take photographs that only expose the sensor (or film) for a very tiny fraction of a second. This is a simplification that ignores many factors, but you can think of it as: the shorter the exposure (also called shutter speed) the sharper the image. This is because any subjects that are moving will create a blur if the exposure is long, since they will occupy more than one point in space during the time that light is exposing onto the sensor.

Additionally, if we use typical aperture sizes, or f-stops, (think of it as the size of the hole letting light pass onto the shutter) we can let in a lot of light during that very quick exposure. If the shutter is open too long, then too much light will hit the sensor and the shot will be over exposed.

Long exposure photography flips these conventions on their head! We'll use very long exposures -- anywhere from 4 to 30 seconds for our Light Paintstick images -- so that our subject (the NeoPixels) will occupy many different points in space during the time that the shutter is open. But, to avoid over exposing the sensor and creating a blindingly bright image with no details, we'll use a very small aperture. This means that only very bright objects (such as our NeoPixel LEDs) will send enough light to the sensor to be exposed on the final image.

The size of the aperture is expressed in f-stop values. It can be confusing at first because the lower the f-stop number the larger the opening. This is because the f-number is a ratio of focal length to aperture diameter.
Typical settings for "normal" daylight photography are fast shutters -- 1/250 second for example, and wide open apertures -- f/5.6 for example. Long exposure photographs taken in dark settings will use slow shutter speeds such as 4" (seconds) to 30" and small apertures such as f/22.

Tools

Ideally, you will want to use a good camera with manual control over the settings, mounted on a tripod. Any mirrorless system, DSLR, or higher-end point-and-shoot should give you the control you need. The camera will need to allow you to shoot either long exposures or in "bulb" mode where the shutter stays open indefinitely until you release it.

Alternately, you can use a smart phone and dedicated apps. Search for the terms "long exposure" and "light trails" to find some options.

Don't forget that the HalloWing has an ON/OFF switch!

Action

Now, you get to start experimenting! Start off simply, with a rainbow pattern. In a dark environment, set up your camera, trigger the shutter, get in front of the lens, turn on your Light Paintstick, and sweep an arc shape over your head.

Release the shutter and check out your photo! You can now start to tune the settings to dial things in.

Next, try some longer exposures and run around with your Light Paintstick. Get creative! It's also fun to have some context in you photos, so try tuning the exposure settings on your camera so that some of your environment is visible, not just LED streaks against black.

led_strips_L1007376.jpg
This photo has been over exposed a bit and a flash triggered so you can see the scene and light paintstick path/action
led_strips_L1007473.jpg
When no flash is used the subject doing the light painting is "invisible"!

Floating Images

Now, you can try stamping an image into midair! Switch the CircuitPython code LOOP = True to LOOP = False and re-save the code.py file onto the board so that you're displaying one of the individual bitmaps, such as the pumpkin.

You will want to tune the speed of the play back so that the image draws in about 3-4 seconds. Set your camera for a 5-6 second exposure. Trigger the shutter and then move the Light Paintstick in a straight line parallel to the camera.

You can draw logos in midair, too!

Bats!

Multiple Stamps

You can trigger your image multiple times during a single exposure, just try to not overlap! Also notice that you can create a "backwards" image by moving the want from left-to-right instead of right to left as with the bottom pumpkin shown here.

You can also switch the code back to looping LOOP = True so that as long as you move the wand the image will repeat.

Here's an example of this on a playground merry-go-round.

If your image is squashed, try turning the potentiometer to the right a bit so that it draws the raster a bit slower. If the image is too wide, turn the pot to the left to speed things up. You'll want to still move the wand at the same speed so that you only adjust a single variable at a time.

Here's an example of the same image being played back at  different speeds by tuning the potentiometer between takes.

Rotate your arm in a big circle!

Have fun with your light painting! You can even start to get fancy and include yourself in the photos -- just draw your images as usual in the air, and then at the end, hold very still and point your Light Paintbrush at your own face for a few seconds to add it to the exposed portion of the frame!

So, have fun experimenting with different artwork and techniques as you explore the fascinating art of long exposure light painting with your HalloWing Light Paintstick!

Note, you can create some creepy outtakes while you're at it.

Here's the ghost of photographer Joel looking highly weird. This is what happens when you test the long exposure + flash theory. NOTE: He is not wearing a mask.

This guide was first published on Aug 24, 2018. It was last updated on Aug 24, 2018. This page (Take Long Exposure Photos) was last updated on Aug 24, 2018.