Yep every once in a while I write a post about photographic lighting. I only do this when I stumble across something that I think my answer a lot of questions really quickly. I much prefer the "hands on approach" that I use in workshops that I do every once in a while. I prefer this because you can learn more in 5 minutes actually relating to the distances/spaces/angles in person than you can in a lifetime of looking at diagrams and descriptions and resulting images. I guess video is a little better but nothing like being there.
Okay - I had a reader write me about an image posted somewhere in an Aperture article. Actually it was a series of images that happened to be in a screen shot of an Aperture screen from way way back. The question was not about Aperture at all, it was quite literally "why does your softbox look different than mine?". After a long email exchange - that answer came down to distance and fill light. I thought boiling that discussion down maybe useful to some of you that are have started to take your flash off the top of your camera. I randomly picked an image from the sequence that we discussed that happened to use a couple of the things that we talked about. It's a JPG strait out of the camera - my usual M.O. when doing workshops.
When working with any light and especially a softbox or something similar the main goal is getting a bigger light source. If you make the light bigger but have it really far away it doesn't accomplish much. You want to get it close - really close. Just about everyone knows this - well not everyone, in fact most people's issue is that their definition of close is really not that close. At some point when you reinvent your definition of close the results are still not what you "expect". Why is this? Well if you happen to have a really really really gigantic light source and you are taking a picture of something really really small one light really really close may work extremely well. In most cases the biggest things you are going to use practically are a 3x4 or 4x6 box or smaller on normal sized things like people.
Getting a light source close does two things simultaneously, the first and usual goal is to make it "softer" or in other words make it bigger in relation to your subject. The second thing that it does that is usually unintended, at least to the lighting newbie, is that it makes everything else darker - your background - your reflected fill light - everything. In a way this makes it harder at the same time. Most people's definition of "soft" when it comes to lighting visuals is a gradual shadow transition AND a somewhat close ratio between fill and main lights - sort of - you do not usually want it really "flat" - soft but not flat. Soft = good, flat = bad. At least my taste. The effect of moving your box closer and closer in a lot of cases can be counter productive to what you are trying to do. In summary you want it close but not too close, in most cases you want it closer than it is without causing everything else to get dark and the lighting ratio to increase too much.
What to do? Well you could add a fill light but that is for wimps and usually is not the best solution, not that adding a light is bad but most of the time it makes things more complicated and can lead to FLAT. It also chucks another catch light in the eyes (not good) - this is not the case if your fill is really really really really big but that takes a lot of work and space - usually not a reality for most location shots.
Wait we can use reflectors - yea that's it. The problem with reflectors is as you get your softbox closer and closer the reflected light becomes darker to the point of pretty much useless if you want your box really close. most people solve this by placing the reflector as close as possible and then adjusting the distance of the softbox distance until they get the ratio they want. I am going to offer you a better way right now and the one most of my workshop participants are shocked at when they see the way I setup my lights.
Here is the big secret that works really well with softboxes and reflected fill - get your box really close and point it away from the subject towards the fill. Not all the way away of course but more away than flat on your subject. In most cases your softbox can be pointed so that the front is almost perpendicular to your subject plane. Doing this does a lot of things without changing the overall characteristic of the light. It changes the way specular highlights are rendered in some very interesting ways that you probably do not expect - in a lot of cases for the better. It increases the effectiveness of your reflected fill - be it from your environment or reflectors that you placed yourself. It can cut the light out of one side of the picture or reduce it. The real magic is that you can adjust how much of these things happen or don't happen by simply twisting the way your box is pointed a little this way or a little that way.
So the image at the top - A reasonable sized room but not gigantic and to be blunt a little close for my taste. To camera right I have a 3x4 box really really close in front of the subject and a little to the right. Just out of frame. maybe 20 degrees to the right and in front. About 2 1/2 - 3 feet away. Really. It is pointed way more to the left than at the subject. On the left I have some very large white reflectors that run from in front to behind the subject. The walls would have done to but would have polluted the color a bit since they have an odd green-ness to the off-white. There is one other light - it is very far behind the subject on the left side. A 1x3 softbox that I have twisted, angled, and positioned in such a way that it is providing light on the background that is about 1 and 1/2 stops less than the main while providing a subtle rim light for separation on the left that is about 2/3 stops less than the main. That light has nothing to do with fill. In fact if you have two lights the last thing that I would use the second light for is fill unless you are going for flat.
Here is another with the same concept - box is a little to the left and in front of the subjectmaybe 10-15 degrees off axis of where I am standing about 2 1/2-3 feet from the subject but it is pointed more up than right down at the subject. There is another light for the background and very very subtle rim light but it is angled so far behind the subject that it has nothing to do with the fill - you can see it where the light actually starts to go into black and then get's lighter again.
Ps. If you want more lighting stuff let me know, the only thing I have to go on if feedback from readers.