If you’ve been making shots in a studio for a while, you’ve probably collected a number of light “modifiers” – that is, reflectors, softboxes, umberellas and other bits of metal, plastic, foil and fabric to control, block, reflect and otherwise guide the light to where you want it. But do you know what they actually do? Neil Van Niekerk tested some of his light modifiers and you can the results of Neil’s tests on his excellent blog Tangents <<- click. I thought I had better test mine. I found some interesting and one or two unexpected results.
I’m testing for 4 things here:-
- The size of the light pattern
- The rate of fall off at the edge, and where it starts from (ie does it fall away right from the centre, or remain fairly even up to a point, and then fall off).
- The overall light intensity (how much light does each modifier eat)
- The quality of shadows cast by an object in the light
All but the last few tests were conducted using a 600 Watt-second Lencarta SuperFast studio head. The light is 2.5m from the background and one stop up from minimum power to give an exposure of f/8 at ISO 100. If you’re rooting around in the EXIF, you’ll notice that it says f/4. I used a huge 50mm f/4 Zeiss lens from a Pentacon 6 medium format camera on an adapter for these tests and the camera has no idea what the aperture is actually set to. It says f/4 in the EXIF because I defined the lens in the camera’s list of manual lenses like that. On my D800/D810 bodies, these random chunks of old glass work perfectly – with full auto exposure possible, and you even get the focus indicators in the viewfinder as you move the manual focusing ring on the lens. This old (circa 1964) lens has a much larger image circle than a lens meant for a 35mm camera, and the adapter has a ball socket in it to enable tilting. I used it for this test, purely because it was to hand and most of my lenses were packed for a wedding shoot…
I also placed a C-Stand about 1m from the background to cast some shadows. I put the boom arm on it to create a T shape, as you will get different shadow quality from horizontal edges and vertical edges, if the light source is bigger in one dimension than the other. E.g. if the light source is a tall thin slit, then the vertical objects will have sharper shadows than the horizontal objects. Note: a lot of the general ripples in the light pattern, are from my saggy grey vinyl background. It’s rarely in focus in real shots, so isn’t a big issue. I am about to paint the walls Dulux Ice Storm II which is about 18% grey too – see this post by Damien Lovegrove, so I’ll be able to retire the vinyl soon.
For the last few tests, I used Speedlights (small flashguns) as they have a smaller, centrally mounted straight flash tube that does not create problems with light focusing systems like the light blaster or the Fresnel adapter. The adapter I have, like most Fresnel light focusing systems is meant for a constant LED light source which is also centrally mounted – like any theatre light that has used this technique for decades – they are not really meant for studio strobes with big round flash tubes – they may work well with hybrid lights like the Godox AD360 or AD200 that have small knots of curly flash tube.
Grids do a good job of making a restricted beam of light. The light fall off is even, and gradual and starts near the centre of the pattern. They also retain more light overall, than say, a snoot, which absorbs a great deal of it. You also get similar size of light patterns from some wildly different sizes of modifier (standard reflector with grid vs beauty dish with grid). However, different sizes of light source also affect the shadow quality, and the smaller you get can make it (from the subject’s point of view) the sharper the shadows cast by the subject will get. You can do this by either just using a smaller light source, or moving further away so it appears smaller from the subject’s position. The snoot, for example, makes a light pattern similar to the 10 degree grid (just not as bright), but casts sharper shadows at the same distance. If I moved the grid further away the shadows will get sharper, but of course, the overall light pool will get bigger, and the light intensity will reduce as well, as the same amount of light is covering a wider area.
Barn doors are fairly useless for creating a small slit of light. This is because they are really close to the light source, and so shadows cast by the doors edges are really soft. If you want a nice controlled slit of light, cut a slit in a large piece of cardboard and hold that close to your subject while the light is further away (this is known as a cucoloris or “cookie”); or use a light focusing system like the Lightblaster, or other spot projector. Most lighting systems have a spot projector available that will take a “gobo” (GOes Before Optics). A gobo is a shape usually cut into a piece of sheet metal that is used to cast a focused sharp shadow by pumping the light through it, and then through a lens of some kind. Some spot projectors have adjustable blades in place of a fixed shape gobo, to make small slots of light.