PhotoPlus_Issue_128_July_2017

Traffic Trails
STEP BY STEP Be a trailblazer
How to set up your DSLR for a series of long-exposure light trails
01 Get set up
Fix your DSLR to a tripod. Look for an angle where the
winding road begins close up then recedes into the
distance, as this’ll make more interesting lines than,
say, a side-on view. Try a low-down or high-up view, and
frame loosely to account for different-height vehicles.
02 Switch to manual
Rather than shooting in pitch dark, try just after sunset
so there’s still detail in the sky. Even so, autofocus can
struggle to lock on in low light, so focus on a point a
third of the way into the scene, then switch to manual
focus to lock it. This’ll prevent hunting between frames.
Using
Manual
exposure
If you find you usually
stick to the auto exposure
modes, a project like
this offers a gentle
introduction to Manual
exposure mode. In order
to get the long shutter
speeds we need, we
have to adjust our other
exposure settings to
compensate. Firstly
we can use a high
f-number like f/16. This
decreases the size of the
opening in the lens and
restricts the flow of light.
Secondly, we can use a
low sensitivity, such as
ISO100, so the sensor
requires more light for a
correct exposure. Both
factors help to restrict
the amount of light,
which means we can use
a longer shutter speed
that will blur any motion.
03 Set your exposure
Switch your DSLR to Manual exposure mode. All
scenes are different, but here’s a good starting point
for exposure: set the aperture to f/16, shutter speed
30 secs and ISO100. If the image is too bright or
dark, try adjusting the aperture until you’re happy.
05 Combine several images
Open the images you want to use (we blended seven) in
Photoshop. Choose one frame as the base image, then
go to another image, Select All (Cmd/Ctrl+A), Copy
(Cmd/Ctrl+C) then go back to the base image and
Paste (Cmd/Ctrl+V). Repeat for all the other images.
04 Time it right
Shoot lots of frames as vehicles zoom by. Differences
in height make the trails more varied (as will flashing
lights, which appear as dashes). Take care not to nudge
the camera between shots, as we need all the frames
to be in alignment if we intend to blend them together.
06 Blend the layers
Go to the Layers panel (Window>Layers) then change
the blending mode of all layers to Lighten, which
effectively overlays the trails on top of one another.
If any other areas, like the sky, look messy, use a layer
mask or the eraser to remove them from the mix.
Quick Tip!
Use a 2-sec selftimer
drive mode
if you don’t have a
remote control so
you can start the
exposure without
nudging the
camera
The Canon Magazine 57