Welcome to my new blog!
I figured I should just hit the ground running, starting with a tutorial.
Lately, I’ve been really interested in using flash to make the background dark (or even black) when I’m photographing flowers outside during the middle of the day. Impossible, you say? With a bit of planning and some tweaking, it is possible.
Flash/Speedlight Primer:
First let me give you a little primer on flash photography. Let’s say that you wanted to take a photo of a person against a light-colored wall, and you wanted to make that background light-colored and then dark-colored. As it turns out, the distance the subject is from the background is the key, as well as the distance the flash is to the subject.
I’ve created a couple of diagrams that I hope will help you understand.
If you wanted a light-colored background, you would place your subject close to the light-colored wall, like so…
But if you wanted a dark-colored background, then you would place your subject farther from the wall while keeping your light close to your subject…
Using that information when you are outside with flowers will help you get darker backgrounds.
Also Consider:
The other thing you have to consider is removing as much of the ambient light as you can and rely mostly on the light coming from your flash. The best way to do that is to take a photo with the ‘correct exposure’, then stop down your exposure by 3-5 stops.
To stop down your exposure, first you should increase your shutter speed to your flash’s maximum sync speed (my Canon Rebel T2i has a max sync speed of 1/200s… check your camera manual). If that is not enough then you will need to stop down your ISO, then your aperture.
For my camera; f/8.0, 1/200s, ISO 100, is a good place to start… with my flash at about 1/8 power, then increase/decrease the power of the flash until the subject is properly exposed. It will take some trial and error. The distance that your flash is from your subject will dictate how much power you’ll need from your flash.

f/11.0 1/200s ISO 100 with ring-flash attached to 180mm macro lens

f/8.0 1/200s ISO 100 with ring-flash attached to 180mm macro lens
*In the interest of full disclosure, I increased the exposure in the previous two photos by 1/2 a stop in camera raw. But sometimes that isn’t enough tweaking…
Sometimes you’ll need to tweak your photo a bit in post:
I took this photo at the ‘correct exposure’…

f/7.1 1/60s ISO 100
Then I stopped down the exposure by about 2 stops, and added light from the flash…

f/8.0 1/200s ISO 100 with ring-flash attached to 50mm compact-macro lens
It was pretty bright out when I took that picture, and on my LCD screen I thought it looked correct, it wasn’t until I got home that I realized that it would need some tweaking.
In order to get it to look like this…
I had to tweak it a bit in Photoshop (camera raw) I increased the exposure by 1/2 a stop; increased the contrast, whites, & highlights; decreased the blacks; and increased the vibrance & saturation. * Full disclosure, I also had to use the adjustment brush with decreased exposure and shadows to get rid of those pesky lighter leaves in the background.
Of course, it is always best to get it right in the camera so that you don’t have to do much, if any, post processing. Had I increased the flash power and dropped the ambient light a bit more (by decreasing the aperture to possibly f/11.0), I probably could have gotten this photo without so much post processing. Again, at the scene I thought I had it correct.
Now pushing the blacks down and the highlights up will NOT work on every photo… the reason it worked here was because I almost had it correct in camera, which I achieved by using a flash and stopping down the ambient light.
For example, I applied the same values from the yellow lily photo above to this photo (which I took without a flash). As you can see, it did not create the same effect. Instead of darkening the background it only darkened the dark areas of the flower.
Creative choice:
When I took the photo of the yellow lily, I had a specific idea in mind… a bright yellow flower on a black background. Tweaking the photo as I have, is a creative choice. I like the hyper bright flower on the black background. I could have tweaked the blacks less and gotten a darker green background, but what I wanted was a black background so I pushed the blacks value to -100.
Would I like to get it right in camera first? Absolutely! And it is something I will continue to practice. That’s the great thing about experimenting, sometimes you get something really cool. Sometimes you learn that you have to keep trying. And sometimes, you get both!
I hope that this tutorial was informative and fun. Tell me what you think. If you have any questions, or need clarification please let me know in the comments section.
Until next time…
~nic