donderdag 6 september 2012

macro photography and flash

Macro photography can be pretty light consuming. You want to maximize depth of field, so you close your aperture to f/11, or even smaller. To get to greater magnifications you might use extension tubes, reducing the light reaching your sensor as well. Or to get rid of the harsh shadows you put a scrim over your working area, etc. To put it shortly, some extra light would be nice.

The first time I encountered this, I was still photographing with a point and shoot. But firing the flash was no option, as I found out that the lens barrel was blocking most of the light. Unfortunately most of the on camera flashes will not be useful for macro photography because of this.

However, there’s also external flashes. I have always been very enthusiastic about external flashes, and the moment I started with macro photography I have been using them. Basically you can use them in two ways, on your hot shoe (on-camera) or external. First I will cover on-camera use.

On-camera use of our flashes is the easiest way of using them. If you use modern lenses and flashes they even communicate to each other, and make a good exposure. But even without this auto-exposure you are very well able to make good photographs. Typically the distance to your lens doesn’t change much, as you want to keep a certain magnification. So the area between the subject and your flash doesn’t change.
A commonly heard complaint about flashes is that they produce hard ugly light. First of all hard light can be really beautiful (but that will be another post in the future), but the light coming from your flash actually is really soft. Your subject matter is really small compared to your flash head, and your flash will be close to your subject, so the light from your flash is still able to wrap around your subject. I took this photo with my SB-24 mounted on my camera, with a diffuser dome.
As you can see, it doesn’t look like your typical hot shoe mounted flash picture, as the light is quite soft.

However, there are disadvantages, as your distance from flash to subject is very small, you will get fast fall-off. If your exposure mainly depends on the flash output, you will get dark backgrounds. You could search for backgrounds which are also quite close to your subject, which will catch more light. Don’t be afraid of distracting backgrounds, as they will be out of focus anyway, due to the small DoF.
Or you could make use of your ambient light. The photo shown above is taken 1 o’clock, in the harsh sun. Even though my flash is my main light, the sun increased the exposure on my background. (That’s why I like to do macro photography, since I’m able to control my exposures anyway, I can do it at any time of the day)

Off camera flash is another option. It can create more dramatic light, and I like it better than on-camera flash. However, compared to on-camera flash, you are less mobile, since you also have to move your light. Besides that, if your subject moves, your flash exposure will change as well. This can be especially difficult since most of us will be using non-TTL triggers / cords / non-TTL flashes. I just hope for the best, and try to move my flash along with my camera, and usually I’ll be all right. Don’t get discouraged because you blow a few exposures, because after some practise you will remember to move your flash.

Again, you don’t have to diffuse the light that much, although I like to diffuse it more. Soft light is more forgiving, and also will create less harsh shadows. (Again, the sun can be your friend and can fill up the shadows) As I use extension tubes, most of my pictures mainly depend on flash for their exposures. This can result in very dark shadows on the other side of your subject. (As you can see in the photo below) Normally an envelope put over the head of the flash is enough, providing very soft light.

So basically, if you want to be very mobile, or your subject moves a lot, mounting the flash on your camera can be a good option. But I prefer to fire my flash from a slight angle to my subjects, so when I can, I will use my flash off-camera.