A couple other considerations besides the color of the light are the flash duration and, the size of the light.
Lee also mentions that when we think about quality of light we don’t generally think about flash duration or sync speed but it’s definitely something we should consider.
Flash duration is a big deal for certain types of photography which require ultra sharp images of moving subjects. If you were photographing an ice cube being dropped into a drink, you would want every single drop of water to be perfectly defined. Flash duration is one major reason why some strobes cost significantly more than others. Luckily speedlights and Einsteins have extremely fast flash duration at a very reasonable price.
So that’s it. Color and Flash Duration. So many photographers will argue that there is something else which is “changing the quality of light” but nobody can actually explain to me what it is. Even if there was some sort of magic flash tube that could make images look “better,” wouldn’t that “magic” be lost when you put it behind a modifier?
Any photographer who has studied lighting knows that the size of a light source determines how hard or soft the light will be. It’s not actually distance from the subject that determines this but the fact that the closer a light source is to subject the larger it will be in relation to that subject.
A larger light further from a subject than a smaller light placed closer to a subject can produce softer light.
Luckily we have modifiers that we can add to our lights to change their size and shape.
There’s a lot of hocus pocus flying around the internet about flash modifiers and for the most part I think it’s pretty silly.
For the most part, quality of light can be effected in 2 ways:
1. The size of the light source
2. The distance from the light source to your subject
The shape of a light source can help as well but it isn’t as important as many people make it out to be.
Softboxes are the standard modifier that I will compare everything else to. At it’s core, a softbox is simply used to turn a small light source into a larger light source. You can buy totally different sizes of softboxes in a range of different shapes but I would argue that their size is the biggest defining feature.
Most softboxes have inner baffles that “soften” the light even more. This simply means that your light will leave the front of the softbox more evenly from edge to edge. I’ve had photographers argue with me that softboxes need to have white interiors rather than silver or that they only use Softlighters because the light is “so much softer” and I’m not buying it. If you want “softer light” simply use a bigger light source. If you want more contrast in your lighting, move your light closer to your subject.
Reflectors could be considered light sources too. The size and distance of your reflector to your subject works exactly the same as a softbox. The shape of some reflectors allow you to craft the light in a way that would be difficult to do with softboxes, but in many cases could be replicated with a piece of white foam core.
Where did this “light quality” crap come from?
So then what is this “quality of light” that photographers like talking about? Perhaps one of the reasons that we are constantly confused by lighting equipment is that we are comparing our unedited work to highly edited images online. We see a picture and assume that it looks amazing because it was photographed with a Profoto Beauty Dish when in reality it has a unique “look” that was produced in Photoshop. If you tried to reproduce the original raw file you would find that any similarly sized light source would be capable of producing an almost identical shot.