Using Flash for Macro Photography
Sometimes when we photograph we get perfect light and other times we don’t so on occasion there might be a need to improve the light and make it close to perfect. While there is not a solution to turn bad light into good light, one tool that can benefit many close-in subjects is the flash.
Flash is a great tool for outdoor photographers and while it has little effect on a sweeping landscape, it is quite useful with subjects closer in like macro or close-up nature.
Today’s dedicated flash units are very sophisticated devices so if you are new to flash, grasping these fundamentals will demonstrate how flash is fairly easy to use.
TWO LIGHT SOURCES
Think of using flash as two separate light sources: ambient natural light and the flash. Each light is controlled for the most part, by separating the settings both on-camera and on the flash.
As you know when using your camera to take a photograph you can use your aperture or shutter speed to adjust exposure to brighten or darken the picture. With flash use, it is common to divide those tools when controlling either the flash or ambient exposure.
Shutter speed has no control over flash exposure but aperture does when using Manual Flash. Changing shutter speed only changes ambient light exposure. With the flash firing as soon as the shutter opens, the light peaks and quickly dissipates while the shutter remains open to record ambient light. Here are two examples:
This image is f/8 at 1/10th of a second.
This image is one stop darker on ambient light: f/8 at 1/20th. The background is darker but the flash exposure is the same.
Aperture can control flash exposure just like it changes ambient exposure but only does that when using manual flash. Using a small aperture like f16 means it takes longer for light to come through the lens at a specific shutter speed while a wide aperture lets in more light at the same shutter speed.
So if you are using flash in a manual flash mode so it outputs the same amount of light each exposure, changing aperture changes flash exposure and ambient exposure. If you prefer TTL features and you adjust aperture, the flash compensates that change by adjusting output. So to brighten or darken flash light, you use Flash Exposure Compensation features on your camera or flash.
The other consideration about TTL and metered flash is that subjects like a large white flower might fool the metering and cause incorrect exposure. So you cannot assume that each flash picture will be perfect but like manual flash, can easily by adjusted after evaluating the exposure.
There are many ways to apply flash to a macro subject. Since we don’t always get the best light for our subjects, flash can be used a fill source with the sun in contrasty light, or as a key light like the sun in flat light. On-camera flash a great option for dealing with that contrast as it fills in or lightens shadows and is easily done when flash is on the camera.
Here is a backlit flower showing the addition of flash. To lighten up those shadows and lower the contrast, I placed my flash in the hot shoe and proceeded to fill in the shadows at a power setting that was subtle to avoid the ‘flashed’ look, yet lighten the shadows in a more pleasing, natural looking manner.
The on-camera approach places the flash essentially on the same axis as the lens thus preventing ‘cross lighting’ (where highlights and shadows are created by the flash that compete with the suns highlights and shadows due to the flash coming from a direction other than the lens axis).
FLASH KEY (aka Faking sunlight)
While the previous examples were about lowering contrast using light from a flash, you can also increase contrast on a subject by adding flash to those subjects in flat light. In this case the flash no longer is the secondary light source like it was when used with the sun. Instead you make the flash the primary light source and natural light secondary.
This is easily done by setting the flash to be brighter and you can do it with the shutter speed like we just saw. As an example, let’s say the camera suggests f/11 at 1/30th of a second and using TTL, the flash outputs the correct amount of light for f/11. You can change the shutter speed to a faster setting depending how dark you want the background to be. The darker the background the more pronounced the flash ‘look’ due to the elimination of the ambient light.
Here you can see the flower with just natural ambient light. In this example the light is all natural. While this image could be processed by adding contrast and saturation and look great for sure, it lacks lighting contrast.
This image has the flash to the side and triggered wirelessly. This is a raw flash and you can see it has hard shadow edges but has added contrast that helps.
In this image a Fotodiox mini light box is used and the shadows are softer but the lighting contrast is still improved.
Here is the Fotodiox in position and at $13 it works great for the price.
You can move it close to the camera for more of a fill light or you can move it further to act like the sun and create highlights and shadows on the subject.
I also have a clamp that attaches to my light stand and I can then use my tripod like a light stand. I simply invert the tripod head and place the camera at the correct height for the subject and then attach the flash and wireless trigger to a flash bracket and use the clamp to attach to the tripod.
You can get these at Cowboy studio here and the part numbers for the clamp is:
Studio Gorilla C-Clamp with 5/8 inch Stud, SA-35D
And the flash holder is: Flash Shoe Holder Light Stand Mount, Mount N
Like everything in photography, your imagination is the limit and flash is very useful tool for nature photographers and with most any subject. It’s a great way to get a subject to separate from its surroundings by creating lighting contrast just like depth of field does. You can light a subject to be brighter than the background and when you do this, the subject will pop stand out from the surroundings much better. Adding flash to subjects in contrasty light brightens shadows and lowers contrast for a more pleasing image. And you can light specific areas of the scene when you stash your flash in the scene and hidden from view.
Whether you have a new state-of-the-art flash or an off-brand model, all you really need is the ability to create light that benefits your subject by enhancing a static subject, freezes a moving subject, or lowers contrast.
If you have any thoughts please leave a comment.
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