Creating Dark and Light Backgrounds in Your Macro Images
By Kevin Palmer
Many photographers like jet black backgrounds in their macro images because the subject seems to "pop" in dramatic relief. Additionally, it often removes distracting or ugly backgrounds and if composed well, images can be down right artsy. But on the other hand, a black background rarely tells a story about the subjects environment and in the case of a darker subject, perhaps the dark background doesn't do it justice. Regardless of the reasoning, sometimes it just pays to experiment and shooting differently exposed backgrounds can be easy with a cooperative subject.
Light, Shutter, Aperture, ISO
Unlike cooking a gourmet meal, there are only four ingredients that go into exposing foregrounds and backgrounds. It is how you mix them that makes the difference. When shooting macro or very close focus wide angle, you will generally have more latitude with your settings because you are close to your subject. At close proximity, it is easy to have enough strobe power to light your subject even when you have chosen light restricting settings - this makes black backgrounds easy.
It is also worth noting that to create the preferred effects with your backgrounds, it will always be easier shooting in full manual. It doesn't mean you can't make it work with some auto-exposure settings, but it is easier in manual. Popular cameras like the Olympus TG-6 that don't have full manual and only a few aperture settings and shutter sync speed options will have more difficulty than a camera with more flexibility.
Here is a quick analysis of what each of our four ingredients does:
Unless you are shooting at night, you are usually working with two sources of light. One is coming from your strobes or constant lighting device, the other is ambient light usually coming from the sun. Ambient light can be very subtle if you are deep, the sky is cloudy, its early or late in the day or you are diving in an overhead environment. But ambient light can be quite bright if it is shallow mid-day conditions or if you you are angling your shot towards the sun.
The range of shutter sync speeds (the shutter speeds that the camera allows you to successfully fire a strobe with) that are available to you will vary from camera to camera. The default slowest sync speed for most cameras is usually 1/60th of a second, though this can be adjusted. The fastest sync speed varies widely - usually from 1/160th of a second to 1/320th of a second. You sometimes have to raise or lower the allowable sync speed in the menu based on your needs.
The most important rule of shutter speed is that it has no effect on strobe lit foreground subjects. Most strobes fire for a shorter time than the shutter sync speed, so the exposure is entirely controlled by your strobes on your primary subject. Conversely, shutter speed has a significant impact on the exposure of ambient lit backgrounds.
Unlike shutter speed, aperture influences the amount of all light that enters the camera lens; both foreground and background. While this is true, since we are working very close to our subject, we can largely compensate the apertures effect on the subject by adjusting our strobe power.
ISO increases or decreases the sensitivity of the camera to all light, so when it comes to light, it functions in much same way as aperture, although the influence on dynamics other than light are different between the two.
OK, that is a lot of preamble for a fairly simple set of rules for back ground exposure, so lets get started.
Rules for Black Background Close Focus Photography
- Shoot the fastest shutter sync speed your camera allows. Note that some cameras will exceed the "listed" max shutter sync speed with an LED flash trigger.
- Shoot the lowest "native" ISO the camera allows. Usually ISO 100 or 200, though sometimes as low as ISO 50 or 60.
- Since we are shooting macro oriented images, a fairly small aperture is the norm already. This will vary from perhaps F11 or more on a 1" sensor compact, to F18 or F20 on a full frame camera. Too small an aperture can soften the image through diffraction, so don't over do it.
- Adjust your strobes accordingly for exposure and try not to spill too much light behind the subject.
- Lastly, and importantly, compose your image so there is some open space behind it. On low subjects like a nudibranch, that may mean getting low and shooting straight or a little up. With a coral goby on a wire coral, you automatically have an open background. If you have a fan, sponge or muck right behind the subject, it will be hard not to light the background matter without restricting your strobe light further with your hand or a snoot.
Easy right? Just a few things to remember as you experiment. Remember that if you change your ISO, it will effect every aspect of your exposure. If you change your aperture it will also effect every aspect of your exposure. If you change your shutter speed, it will only effect your background exposure and finally, your strobe power should only effect your foreground exposure (if aimed correctly).
Remember that one of the reasons we choose NOT to make a black background is to complement the subject color and give a sense of environment. This dark Rhinopius below, would have been as interesting with a black background.
Rules for a Lighter blue or Green Background In Close Focus Photography
- The most important change for this type of image is to shoot at a lower shutter speed. for some this may mean only a small change from 1/160th down to 1/100 or 1/80. If you normally shoot at 1/250, you get a bigger adjustment. You can go down to 1/60th of a second, but, the background may get a bit soft if there is motion (this may not matter with shallow depth of field). Before you get close to your subject, shoot a mid water background and see what you get. If it still looks dark go to the next step. If it looks blue - you are good to go.
- If shutter speed is not enough, try reducing your aperture by one or two stops (smaller number). This will lighten the background, but you will need to compensate by adjusting your strobes to less power so you don't overexpose the foreground.
- If you are shooting something tiny, like a hairy shrimp on algae and you are worried about depth of field being lost by opening aperture, you can alternatively raise your ISO and leave your aperture alone. This will lighten the background as well, but remember to lower your strobe power here as well.
- Blue backgrounds (or green depending on water color) are usually achieved with an upward shooting angle. The higher the angle you can achieve, the brighter the background water will look. You can even shoot very nearly towards the sun if you adjust your settings correctly.
Blue backgrounds are slightly more complicated to shoot only because you are trying to fine tune the right exposure to create a pleasing tone in the water that compliments your subject. For a black background, you can't really can't overdo it just make it black and you are good.
Photo Shen Collazo
The more you play with these simple concepts, the more you will discover in your experimentation. Don't get stuck in a rut - you can transform the look of your work with the spin of a camera dial! If you have more questions, don't hesitate to reach out to us here at Reef Photo. We are happy to help. We also cover many of these techniques in our workshops.