12.26.2012

How To Fake a Backdrop With Flash

Do you fancy those dim lit portraits with the subject's face lit and surrounded by darkness? I'll be you think you need a professional studio, backdrop and a ton of fancy lighting to achieve that same effect huh?

If you know anything about flash photography then you already know that you an fake a black backdrop... But did you know you can fake it even outdoors on a sunny day?





How to simulate a black backdrop even outdoors on a sunny day.
 All you need is your camera, external flash (a speedlight will do) and a light stand.

All you have to do is shut out as much ambient light as humanly possible. Once you have your black ("under exposed") image then you are ready to use your flash to illuminate only what you want to add back in. You are essentially overpowering the ambient light with your flash.

You'll need a camera that has a manual mode. You must be able to control the ISO, shutter speed and aperture to achieve the desired results. Your flash also needs to have manual controls so you can adjust the intensity of the flash.

With the flash being off-camera, you'll also need a way to trigger it... You have a couple options here:
- Hot shoe extension cable.
- Wireless trigger: The PocketWizards are the best money can buy. It opens up a whole new world for you and off-camera flash photography.
- Your Camera & flash's built in slave. That is one of the many reasons I love Nikon. They have made it so easy to fire your Nikon brand flash using only the pop-up flash on your camera to trigger it. My Nikon D800 and Nikon SB-900 work great together.

Now that we have gear covered, let's get into the technique...

First, set your camera's ISO as low as you can. This setting comes from the good ol' film days where you had to buy film with ISOs that were suited for what you were going to take pictures of. ISO 100 was for extreme daylight while higher numbers like ISO 800 or 1600+ were for indoor, dark locations. Using an ISO like 100 means that it will take a lot of light to expose the image. ISO 1600+ need less light to expose the image. For our needs, we want it to be really tough for ambient light to affect our exposure.

 the shutter speed needs to play nicely with your flash. Although the two really don't have any effect on one another you do need to be wary of your camera's flash sync speed. This is typically 1/200" or 1/250" on most cameras. Refer to your camera manual for that info. If you go higher than this sync speed then you will notice a black bar affecting your image. This is from the shutter closing before the flash has time to fully fire.

I leave the aperture last because this setting IS something your flash works with. The aperture is the opening in which the light enters while the shutter speed is the duration of how long that light gets let in... The lower the f-stop (f/4, f/2.8), the bigger the opening and thus the more light gets let in. The higher the f-stop (i.e. f/8, f/16) the smaller the opening so less light enters.

I would recommend your camera to be set to ISO 100, 1/200" and f/5.6 as a starting point... This is a definite balancing act. We are probably maxing out the ISO and shutter speed due to camera and flash sync limitations.* The only things we can tweak now are the aperture and flash settings.

 * fun fact: The Nikon D70 has a 6mp sensor but has an electronic shutter with a flash sync speed of 1/500"! You better believe I own one of these cameras.

Take a test shot without a flash. If your test shot still shows some background and ambient light then the only thing you can do is raise the aperture to f/8, f/11, f/16, etc. As a last resort you can find a little shadier spot to position your subject in. That little bit of shade could be the difference you need.

Now that you have successfully killed the ambient light, it is time to incorporate the flash. You cannot change the settings of your camera at this point. You have locked down your settings to achieve essentially your black backdrop.

The flash has 4 things that can affect it's impact on an image. Two are camera settings and two are flash settings:
- The ISO
- The Aperture
- The flash's power
- The flash's distance to subject

We have ISO and Aperture locked down so we can only control the flash's power and distance between flash and subject.

Put the flash an arm length or two away from your subject to start and then dial the flash's manual power up or down until you have the right intensity of light. Once again, the flash should be in manual mode and you should be working with flash power that is something like 1/1, 1/2, 1/4, 1/8, 1/16, etc...

You will see in the image above that a soft box was used outdoors to literally soften up the light. This also helps to wrap the light somewhat around your subject's face instead of just being harsh with a hard stop between shadow and highlight.

Also, notice the position of the flash. It is on the opposite side of where I am taking the picture and "fanned" out to help with that wrapping of the light around their face.

Feel free to try the same thing indoors. If you don't have a flash then you could always experiment with window light, reflectors and stuff of that nature...

Thanks for stopping by.
~ Michael