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Flash – Controlling the Direction of Light – Part II

Just a quick post for this one, supplementing our original Controlling the Direction of Light article, as we attempt to replicate moody, window light with a camera-mounted flash.

One of our many goals of controlling the direction of our light is to be able to replicate natural light without sacrificing shutter speed and/or noise. For artificial lighting, it’s best to use an external light source that’s not mounted on the camera, but in many event coverage or casual home shooting, we don’t have the luxury of whipping out our lighting equipment to simulate the mood and direction of natural window light, especially in small, tight quarters.

Revisiting our other article, DIY Bounce Cards and Flags, beyond swiveling and tilting our flashgun’s head, using bounce cards and flagging sheets allow further control on our light. A flag prevents light from travelling a certain direction. The closer the flag is to the light source, lesser the chance stray light can spread, the greater the restriction we have on our flashgun’s light path.

Here I have a snapshot of my son taking his afternoon nap. The warm sunset light skims through our windows and curtains left of the camera frame, as the light bounces around our white wall and ceiling.

Without using flash, our ambient photo has good lighting “drama”, if you’d call it that. However, that required me to use a very slow shutter speed and high ISO for my chosen aperture.


1/5sec, f/5, ISO 1600, Daylight WB.

Our problem is obvious, we have considerable camera shake despite the subject being relatively still. ISO noise is high as well.

This is our reference image, so please take note of the shadow direction near the feet, underneath the teddy bear, and the highlight on the subject’s cheeks.

Now we mount the flash on with the relatively similar settings, firing straight at the subject. A 1/4 CTO gel was attached to simulate the warm light.


1/8sec, f/5, ISO 1000, with flash and 1/4 CTO gel.

Side note: The shutter speed increase was an accidental nudge of the shutter dial, not a deliberate adjustment. The minuscule shutter speed change doesn’t affect the image compared to 1/5th.

Looking at the three areas I’ve mentioned previously, the feet’s shadow, the teddy bear’s shadow, and the cheek of the subject, you can see that with a direct, on-axis flash, the shadows are filled and we’ve lost most of the direction of our light despite the flash merely acting as supplementary light.

So, we’ll now turn the flash head to the left of the camera, and tilt it a little higher (about 30deg upwards) right at where the window is situated and let the light bounce off from the curtains and wall.


1/250 @ f/5 ISO 400

We kept the aperture the same but we raised the shutter speed to the camera’s x-sync speed. This alone pretty much guarantees a sharp, motion-free image. I also lowered the ISO down to 400 to reduce noise. Compared to the previous setting of the direct flash. We now turned the flash into the primary light and pretty much took out all the ambient light.

In addition, I manually changed the zoom of my flash head to 105mm (maximum setting for this flash’s model), that narrowed the beam of light and minimized light scattering to the sides of the flash head.

Now, if you’re confused about the setting change, I’ll try to explain it further. With image #2 (1/8th @ f/5 ISO 1000), the exposure is calculated as if there’s no flash at all, it’s almost similar to the ambient-only, image #1, but with less contrast since the flash acted as a fill.

With image #3, the ambient exposure of 1/250 @ f/5 ISO 400 resulted to almost no exposure because it’s underexposed. The flash acted as a sole light source and that is what lit the whole scene.

Going back to our third image. You can already see that we’re getting more directional light compared to image #2. While it’s not the same as the ambient-only image, you can see that the shadow areas, as well as the subject’s chin, is more pronounced and the shadow shows that the light is coming from the left of the frame.

What we need to do is to further restrict the light to prevent stray light from hitting the walls, which acts as soft-fill light, reducing the shadows of our image (see the line that runs across the shin of the subject).

To do that, I added a black half-snoot or flag, as described in our DIY Bounce Cards and Flags article, around my flash gun. The U-shaped half-snoot blocks light from hitting the floor and side walls surrounding the camera and directs the light beam towards your intended target while providing just a hint of fill towards the ceiling. See the diagram below for a visual cue.


Our resulting image looks like this.


1/250 @ f/5, ISO 200, +1 Flash EV

Pay no attention to the exposure settings for now and just concentrate on the light/shadow pattern. See the line on the subject’s shin has more contrast than image #3. The overall image looks very similar to the ambient-only image, however, we don’t have to deal with camera shake (slow shutter), nor do we have to deal with too much noise because of the low ISO setting.

As you can see, we can get moody, window-lit effects with an on-camera flash, especially in smaller quarters. You can even replicate a through-the-window effect if you put some form of a frame between the surface to be bounced and the subject if you want to get creative.

Going back to the last image’s exposure change, I wanted a cleaner image so I lowered the ISO by a stop. In order to compensate, I have to increase the flash’s exposure by a stop as well, hence the change. That decision was OK considering I was only planning to take a few shots anyway. If you’re shooting in an event, however, where battery life is an important consideration, it’s better to bump your ISO up and reduce the strain to your flashgun’s battery and recycling speed.

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