Sunday, June 16, 2013

Lighting your Subject - Moving the Flash Off Camera

I have frequently mentioned the importance of using light to control light and by extension to control exposure so that you can then use Aperture, Shutter and ISO more creatively. But to control light with light you first need to understand light and what element it adds to photography. For this post I am going to look at a particular aspect of light, hardness, and its contrasting aspect, softness. All of these photos were taken with the EOS 6D mounted on a tripod 4 feet from the subject. The ISO was set to 1600, the shutter to 1/160th, and the aperture to f16 and the lens was at 105mm for all of the images. The main light, or Key Light if you will, was a Canon Speedlite 580 EX-II set to 35mm placed 45 degrees to the subject on camera right and triggered by a Canon Speedlite 600 EX-RT. My subject was 8 feet from the white wall that served as a background. All of the above setting were locked for all of the photos. The light quality was changed with modifiers and distance of the light to the subject. The power output of the light was adjusted as well to maintain proper exposure for the midtones.

Let me just take a moment and go into hardness or softness of light before we continue on to the photos. What is Hard Light? The short answer is that hard light creates a hard edge to the shadows and soft light creates a gradient transition from light to shadow. If you have not looked at An Introduction to Lighting your Subject go ahead and take a moment and look that post over. The second and third images from that post show nicely the difference between hard light and soft light. For the photos below I sat in as a subject so that these differences could be easily observed on the human form.

Ok now we have an idea of what hardness means, how do we control it? The simplest way to think of it is that hard light is a small light source and soft light is a big light source. However the size of the light is not the only thing that effects hardness. Hard light is very uniformly directional. This is a by product of the size of the light but also the distance of the light and what type of modifier the light has in front of it. Perhaps the easiest way to picture this is to think of sunlight on a clear day. The Sun is huge which should create soft light - but it is very very very far away which makes it very very very small in appearance which is what makes sunlight so hard. On the other hand if you go out on an overcast day the whole sky functions as a soft box and shadows can almost completely disappear. What follows are a series of 4 images with a brief description on set-up.

This first image has the hardest light quality, the 580 EX-II Speedlite was mounted in an Interfit Strobies S Bracket with a 7” reflector and a honeycomb and was placed at 9 feet from the subject. The reflector and honeycomb make the flash effectively a 7” light source. The second image has the same modifier but is moved to 3 feet from the subject. It is possible to see a slight softening of the light between the two images, however the light quality still remains quite hard, this is because at 7” the light source is still smaller then the subject even at the closest distance. Another way to picture soft light verses hard light is, soft light is from a source that is bigger then your subject, hard light is from a source that is smaller than your subject.

Light 9' Reflector w/ Honeycomb
Light 3' Reflector w/ Honeycomb

For comparison the soft light from both the 3’ and 9’ distances is using a 36” square soft box. This is a much larger light than the reflector and honeycomb and the softening effect of the larger light is much more evident. In the interest of going from hardest to softest the 3rd images is of the soft box and 9’ and the 4th is with the soft box at 3’. The closeness of the light in the last shot makes it the largest light source in the series.

Light 9' w/ 36" Soft Box
Light 3" w/ 36" Soft Box
This is a brief look at lighting your subject with an off camera key light. A couple of things to point out. The first is that in the interest of changing as few elements as possible the hight of the light was not changed, only the distance to the subject. If you compare the 3’ images to the 9’ images it is easy to see that the hight of the light was much more appropriate for the images at 3’. As you start to experiment with light you will want to light your subject from a higher angle then they are. When you move your light further away the light will need to be raised in order to maintain that angle. Generally light from somewhat above is more flattering. The second thing to notice is that in both of the 9’ images the key light is starting to light the background. It is much more pronounced with  the 36” soft box because the light from that modifier is much less directional, it spills around the room and much more of the light lands on the background. As the light is moved from the subject the ratio between the subject and the light and the background and the light decreases meaning that enough light is starting to fall on the background for the background to expose in the image. I deliberately set up in front of a distracting background so that the use of a closer light source, not only to create softer light but to control light spill in other areas of the frame could be observed. One easy way to get rid of background distractions is to not light them. This is why ISO is not an effective way to control light.

At any rate this should give people a starting point for experimenting with light. Light can seem overwhelming when you first move from natural light and being locked into The “Big 3” and move into modified light. But if you break lighting into small easily understood pieces then you can start to build a skill set which will serve not only with flash, but will allow you to modify ambient and natural light as well.

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