How Bobbi Lane Balances Flash and Ambient Light When Shooting Portraits

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PHOTOGRAPHER: Bobbi Lane
BASED IN: 
Massachusetts, USA
KNOWN FOR: Sumptuously lit portrait images and exemplary training
SHOOTS WITH: FUJIFILM X-T2 Camera, XF56mmF1.2 R Lens, XF18-55mmF2.8-4 R LM OIS Lens

Introduction

Dragging the shutter is a technique that balances the exposure of flash and ambient light sources in the same photo. Taking a photo of someone outside at night using flash while also capturing the city lights in the background is a good example.

Nailing this technique requires practice and persistence, but eventually balancing the brightness of your foreground and background will become second nature. In this Technique blog post, Bobbi Lane explains how it is done and even explains how you can compensate for differences in color temperature too!

Image by X-Photographer Bobbi Lane
FUJIIFLM X-T2 camera

Bobbi Lane

Dragging the shutter is a technique that balances the exposure of flash and ambient light sources in the same photo. Nailing this technique requires practice and persistence, but eventually balancing the brightness of your foreground and background will become second nature.

Flashes can put out a lot of light. In order to balance this with ambient light we need to use a long shutter speed – hence the term ‘dragging the shutter’. This involves color balance as well as exposure balance. Thankfully, FUJIFILM X Series cameras have a flash mode called ‘slow sync’ that (in conjunction with a FUJIFILM-dedicated flash set to TTL) automatically sets the proper shutter speed to achieve this look.

But, with a little bit of practice using manual exposure settings, you can gain total control of your lighting. In this photo, the ambient light in the gallery was not ideal, so I used flash to illuminate the model. However, the spotlights in the photos were interesting and I wanted to include them.

I knew I’d need to light my model with flash and capture the background using the ambient light. The key is to understand how flashes work in the first place. Flash duration can be 1/1000 sec or shorter, so different shutter speeds will not change the amount of flash light let into the camera. You must control flash exposure with the aperture setting, not the shutter speed.

Secondly, it’s important to know your camera’s sync speed – the fastest shutter speed you can use for flash photography. Any shorter than this and you will see a dark band across the frame caused by your camera’s shutter beginning to close before the flash has properly fired. On my FUJIFILM X-T2, this is 1/250 sec.

Step 1: Measuring Ambient Light

Firstly, we need to determine the ambient light exposure. With the flash turned off, take a manual exposure meter reading with your camera. Do this by selecting an F stop, then turning the shutter speed dial until the meter reading is ±0. Here’s what the scene looked like with just ambient light.

This is what things look like with just gallery’s ambient lights. Exposure: 1/20 sec at F5.6 and ISO 200.

There are two problems with this image: first, the electric lights in the background are pretty orange in color; second, the subject is virtually a silhouette. We can fix both of these problems by applying some flash.

Bobbi Lane measures ambient light with the FUJIFILM X-T2. An underexposed image captured at 1/20 sec at F5.6 and ISO 200.
Bobbi Lane explains flash illumination with the FUJIFILM X-T2 with this portrait of Lee Varis.

Step 2: Correct Flash Exposure

Getting the right flash brightness is as simple as setting the same F stop that you used for the ambient light image, then switching the flash mode to TTL. Now, when you shoot the camera and flash will put out exactly the right amount of light to achieve the proper brightness for that aperture.

Take a picture now, with the shutter speed at the 1/250 sec sync speed setting, and you’ll see a properly exposed foreground and a dark black background.

This is what things look like with just flash illumination. Exposure: 1/250 sec at F5.6 and ISO 200.

By comparing these two photos (Step 1 and Step 2) you can see that different parts of the scene are being illuminated by the two different light sources. The flash is only lighting the subject, not the background. And the background lights are not hitting the front of the subject either. There’s no lighting crossover between flash and ambient – if there was, we’d have to take this into account to avoid overexposing the foreground subject.

Step 3: Combining Flash and Ambient Light

The next step is combining the two sources. Repeat the shot you took in Step 2, except now set the shutter speed to the value that you determined when measuring the ambient exposure – 1/20 sec in this case. Now we get this image.

Flash and ambient light exposures at the same time. Exposure: 1/20 sec at F5.6 and ISO 200.

Okay! Now we’re making progress. However, we still have the color problem to solve. Flash light is the same color as daylight (bluish), while the light from the spotlights is orange. When faced with two or more different colored light sources, we need to bring their color temperatures together in order to get a natural result.

Image by FUJIFILM X-Photographer Bobbi Lane
Image by FUJIFILM X-Photographer Bobbi Lane

Step 4: Bringing the Colors Together

In this instance, we can either: put a blue gel, called a CTB (color temperature blue), on all the spotlights in the background; or put an orange gel, called a CTO (color temperature orange), on the strobe light, warming it up a little.

Guess which option is easier? Correct – the CTO gel on the flash!

A couple of things to note, though. The colored gel blocks light, so you need to increase the power of the flash by about one stop if you’re using a flash set to manual. If you’re on TTL, the flash will do this automatically, and you don’t really need to think about it.

Last step: change the white balance setting on the camera to Incandescent (the light bulb) and everything should look good!

Brightness and color are matched. Exposure: 1/20 sec at F5.6 and ISO 200, with CTO gel on the flash and Incandescent WB set on camera.

Step 5: Add Some Creative Blur

This last shot incorporates a bit of fun, which also adds some interest to the image. Since the shutter speed is slow (1/20 sec), I slightly panned the camera during the exposure. This blurs the background slightly, but the subject is sharp because they are lit only by the short burst of strobe, which freezes the image. It’s a great creative technique!

Moving the camera while the shutter is open blurs the ambient-lit background, but not the flash-lit foreground. Exposure: 1/20 sec at F5.6 and ISO 200, with CTO gel on the flash and Incandescent WB set on camera – plus intentional camera movement.

Bobbi Lane is a compensated FUJIFILM X-Photographer.

To see more of Bobbi’s work, visit her website.

To explore the full X Series lineup visit X Gear Chooser.

Image by X-Photographer Bobbi Lane

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