I often get asked about how I create dark / black backgrounds in my macro photos (mainly of flowers) as seen in the shot above, so I thought I would put together a short explanation. More photos like this can be found here https://www.flickr.com/photos/ajecaldwell/albums/72157637234867334
This afternoon I went out to the garden and shot this, largely unexciting, shot of a wilted Gerbera flower, and I will be using this as my example over a series of shots to show how it was created. Throughout this tutorial I will put the camera settings under the photo so you can see the effect of different settings on the look of the photos.
This shot was taken in my garden, right next to the house, at about 5pm this evening. It is early summer here so it was still very light (there is a set up shot below so you can get some idea of the location and setting), with the sun still high in the sky, but this shot was taken in the shade of the house. Behind the flower in the shot were more flowers in the garden and because of the angle I was shooting the mulch on the flower bed was also in shot. The shot below shows the "normal" photo taken from the same location as above, using just the daylight for lighting and exposing the scene "normally". You can see the distracting background in this photo that I want to get rid of, and also how "undramatic" the lighting is on the flower.
You will see from the settings on the camera for the shot above that I use a 90mm macro lens, which has a normal aperture range of f2.8 to f32 (note: due to the way Nikon cameras record aperture when the lens is focused at it's closest distance the lens has an aperture range of f5.6 to f64; feel free to google it to found out why). So with the lens set at f32 I was getting good focus on the flower but the back ground was blurry.
To achieve the look of a dark background I also use a speedlight to light the flower, for reasons I will explain below. I use a simple manual flash (Yongnuo 460II), which is relatively cheap ($NZ80) and has basic controls which allow the power / brightness of the flash to be increased or decreased as required. This flash is mounted on top of the camera ("on camera flash")
The last and most important piece I use to achieve the look I want is a homemade "light deflector / diffuser" which bounces the light from the flash (which would normally head out parallel to the lens) down onto the flower and softens the light at the same time. This is made from a piece of coreflute and is folded to shape to suit the length of the lens, and has a sheet of paper across the opening nearest the flower to soften the light. The shape of the deflector is important to ensure that the light from the flash is directed onto the object in front of the lens from above, and is not shining on the top of the lens itself or behind the flower.
Below is the set up shot for the example flower shot above. (Yes, I know I could have made the deflector look prettier, but I normally don't normally put it in my photos, so it is functional only.) Note: I don't normally use tripod, but to ensure that the images showing the effect of the different settings were consistent I did. The technique is easy to use handheld.
What follows is a technical explanation of the reasons behind the setup, and how it works. I discovered this technique by accident and had to then go and figure out how to replicate the look again.
In a broad outline the technique works by underexposing the scene (almost to black) and then using the light from the flash to light only the flower. But there are physical limitations on this concept caused by the camera and the flash than need to be worked around.
In theory you could just use the fastest shutter speed your camera has (probably 1/4000 or 1/8000sec) and then this would guarantee a black scene... but ... it isn't that simple.
Every camera has a maximum speed where a speedlight / flash can be used effectively; this is called the maximum sync speed. It relates to the fastest that the shutter can open and close and still record the light from the flash across the whole image. If the shutter speed exceeds the max sync speed then you will see an area of darkness across the image where the shutter has closed too fast to record the light from the flash (this explanation is over simplified, again feel free to google how sync speed works)
So on my camera the maximum sync speed is about 1/200sec. This speed will allow me to underexpose the scene nearly to black, as long as I am in the shade. If I am shooting in daylight then it will not be fast enough to darken the scene enough to get the effect.
Below is another shot from the example shot I am using, this time with the shutter set (in manual mode) to 1/200sec which is the maximum sync speed of my camera.
So the only difference between the shot further up the page that was creating a normal exposure, and this shot, is the shutter speed; the aperture and ISO were the same in both shots. This is enough to create a black background (or near enough to it).
The reason to use the shutter speed to darken the scene and not the aperture is that the aperture setting would darken the "ambient" light in the scene the same as the shutter speed but would also effect of the light from the flash; it would darken them both and it would be harder to get enough light onto the object for it to be lit properly. The shutter speed doesn't effect the light from the flash because the flash fires at a much higher speed than the camera.
For the shot below I turned the flash on and used it to light the flower (I adjusted it over a few test shots to get the light bright enough, but not too bright). This is the same shot as shown near the top of this blog.
That is it.
It is reasonably simple to use this technique for a variety of macro shots once you have made the deflector / diffuser, which will only take an hour or so (it can be a bit hit and miss to get it right first time, so a couple of attempt might be needed). This shot below used the same set up (although not on a tripod; I shoot most of my macro work hand held) and was shot in my garage.
This technique can be used to shoot other scenes (like portraits) where you want a darker background with a well exposed subject; just underexpose the scene over all and then light the subject with a flash or torch etc.
It requires a bit of experimentation to get it right for your exact setup but is well worth the effort.
I hope that helps / inspires anyone wanting to create a different look to their macro / portrait photography, and if there are any questions please let me know.