It just depends on what your expectations are and your style of shooting. 8 ft is a > little on the low side. There will be many limitations The ceiling height in my studio > is close to 15ft so I can get pretty much what I want, but at times I have to shoot on > location with low ceilings and I just adapt and get by. How large is the rest of the > space?
The room is 20' deep by 15' wide. To compensate, would I be better off getting a smaller soft box and moving it closer, or a larger softbox at a lower angle?
An 8' ceiling is a common problem but as others have said, you learn how to live with it.
Re your question about softbox size.
The size of the light source relative to the subject determines the softness/hardness of the light.
Both soft and hard light are good, just for different types of portraits.
The general guidelines for soft light portraits are:
1. The source of light, i.e. the face of the diffuser, should be physically as large as or larger than the subject. The larger the diffuser relative to the subject the softer the light.
2. The best combination of softness and light fall off across the subject, which is what gives you the highlights and shadows that make a flat image take on a 3D appearance, are achieved when the diffuser is at a distance between 1 and 2 times the diameter or diagonal of the diffuser.
Closer is softer but the light fall of can be so much that the shadows become featureless black. This can be fine for special case portraits or you can add a fill light to moderate the darkness of the shadows if extreme softness is desired.
Between 2 and 3 diameters/diagonals the light quickly becomes hard and flat, i.e. little light fall off across the subject. Beyond 3 diameters/diagonals you might as well just use the bare light source.
Technically a 43" (110cm) umbrella is the right size for head shots to thigh-up portraits. A 60" umbrella is a better choice for standing portraits but they are hard to use properly in a normal home room with an 8' ceiling.
In practice, because of the wide spread of light from an umbrella, you can use a 43" umbrella at 2 diameters or less and still get soft lighting for a standing portrait. Even if the feet go a little darker than the rest of the body that isn't a problem since the viewer's attention is attracted to the brightest part of the portrait, which should be the face.
A softbox/octabox with a recessed front diffuser sends less light to the sides so you have less stray light, thus a bit more control over subject and background lighting. A recessed front diffuser also makes adding a grid for even more light control easy. Softboxes are more expensive but most photographers eventually switch to softboxes to gain more light control.
A softbox in the range of 3'x4' (90x120cm) is a nice general purpose softbox. You can use it horizontally for head shots or waist up shots of a small group or vertically for a full length portrait with a bit of fall off to the feet.
In my opinion the limited length of your room is just as important as the 8' ceiling height. You need about 1-1/2' of space for background stands, a minimum of 6' separation between the subject and background, and a 15' separation between the subject and camera.
You should look at the various ways of attaching backgrounds to a wall instead of using background stands to give you another 1' to 1-1/2' of distance. Painting or wallpapering the wall to use as a background is also a good idea.
The reason for the 6' background to subject distance is to keep the subject's shadow out of the image. It is also the minimum distance to prevent light coming from a seamless white background causing the edges of the subject to be blown out, or "bleed" into the background.
Note that the 6' distance only works properly for a seamless white background if the white background is only overexposed by about 1/3 to 1/2 stop. Any more overexposure and you get bleeding and you get large light source lens flare that shows up as a reduced image contrast.
The reason for the 15' subject to camera distance is to eliminate distortion. Closer and you get extension distortion (distortion has to do with distance, not focal length, so it is incorrect to call it wide angle lens distortion). Further than 15' and you get compression distortion. Expansion distortion is much more acceptable than extension distortion.
Perspective distortion (photography) - Wikipedia, the free encyclopedia
Ken Rockwell | Portrait Lenses
Extension distortion is small enough that most people won't notice it if you shoot from as close as 10' but any closer and it quickly becomes evident.
I recommend zoom lenses since they let you vary the type of portrait while always shooting from the same distance from the subject, a distance as close to 15' as possible.
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Living and loving it in Pattaya, Thailand. Canon 7D - See the gear list for the rest.
