I have been working on getting a better understanding on the different ways that light can be added, removed, modified, and in general how to make a picture something interesting to look at, and not just an accurate representation of what is in front of the lens. One of the biggest things that photographers do is adjust light. Yes, there are people who can do some AMAZING shots using nothing more than natural light - a candle, a window, the moon, the noon-day sun. Maybe a reflector added. But a lot of what I like is the technical aspect of photography. I'm a gadget kind of guy. So I like to use extra lights to give more textures, more play of light and shadow, more like "art" and less like "crime scene photography".

Strobes are MUCH more powerful and bright than normal room lighting. So if you have regular light, and then ADD a good flash, suddenly the rest of the room light doesn't matter so much, and the only light is the stuff you just fired off. NOW, you can create a shadow. First, a shadow isn't something that is dark, or not lit up. A shadow is something that is lit up LESS then the rest of the picture. If my camera is set at ISO 100, a small aperture, and a fairly fast speed (well, I use 1/120 normally, but the actual strobe duration is MUCH less than that, so it seems quicker) then it takes a LOT of light to make a picture, and anything else is darker. So to get lights and darks, hightlights and shadows, I just need to have some part have MORE light than the other parts.

I have some basic strobes - they look like light bulbs, but fire either when the master gets a signal from the cable you plug into it, or when another light flashes. Most often (since my cable is broke) I use another flash to trigger all the strobes. I have a very inexpensive "cowboy studio" remote transmitter on the camera, and two remotes I can use for a speedlight or portable flash. I put a small flash on one remote, and usually use that as an accent light - and let the rest of the light bouncing around fire the other strobes.

One problem with adding extra light is I usually am using it indoors, in a fairly small room. Like a living room, or a spare bedroom, or the cleared space in the garage. That's a low, white painted ceiling, and four rather close, white painted walls. A lot of bounce, so it is hard to control the light. One strobe will light one side of the face, and the part bounced off the wall does the other side. Great, but too randomly chaotic for me. I want to CONTROL where the shadows and highlights are.

A bunch of the cut bits of tubing
Cooking the bits of tubing to relax them straight.
The resulting grid spot
Enter today's project - the "grid spot". Basically, a strobe will fire and shoot light out in a big wide fan. If I use my umbrellas it is a softer, bigger light source, and even more spread out. BUT..... If I make something that will ONLY allow the light moving straight forward to come out - then instead of a fan I have a beam (with soft edges). There are honeycomb filters that will do that, or the DIY version is made from black straws you steal from your favorite bar when nobody is looking. I used 1/4 inch poly vinyl tubing like you use for a drip watering system ($3.99 for 50 feet of it) and then cut 1 inch pieces of it. The pieces will end up all bundled together, alligned, and only straight light will get out - none of that stuff going off on angles.
The problem is that the tubing was in a roll.... and it all has a slight curve. So - to relax it, I added heat. I ended up using hot glue to connect all the bits together side by side, within a ring made from some plastic on a canister that used to hold coffee creamer. The ring (when done) is wedged into the end of the canister, and the strobe is inside it. I left the plastic bare (frosted white) so that when I trigger my other flash it will kick a bit of light through the white plastic to trigger the strobe inside. Yes, there IS some light that escapes to the sides, to bounce off walls and such, but the strobe is fairly directional and MOST of it goes forwards, through all the little bits of hose. I calculate the spread of the beam is about 10 degrees - that means it lights up a face rather well at 8 or 10 feet, but not much left over to splash on the walls behind the person you are shooting.

Examples. First, I apologize for the model - I didn't have one and had to be my own stand in. Still, you will get the idea of the light (which is the important part).

Shot with natural light - ISO 3200 f/2.4 1/60 exposure
So - this shot is what happens when you let the camera figure out how it wants to expose. It sees the bright outdoors behind me, but is trying to balances the exposure for that, and for me. The result is the background is REALLY washed out, and I'm in shadow (and blurry, but don't nit-pick). The camera went to ISO 3200 (very sensitive to light) and f/2.4 (big opening for light) and 1/60 exposure (long time to capture light)

Shot with grid spot, flash behind, ISO 100 f/4 1/125 exposure

The next shot used the grid spot pointed at my face from 8 feet away, and the little portable flash about 2 feet behind my head. This one I set at ISO 100. For you old timers, this was called "Daylight" film - and heaven help you if you had daylight film and wanted pictures of the kids blowing out the candles..... now with digital cameras you just select what you want to use, and change it any time. The aperture was f/4 - and in photography the bigger the number of the aperture the smaller the hole actually is. I use 1/125 exposure with my strobes - it really doesn't make too much difference because the strobe is very fast.... but I have to use a slowish exposure (instead of 1/500 of a second, for example) so the strobe has a chance to actually fire. I might get away with quicker speeds if they weren't using the light from the other strobes and flashes to trigger. Experience tells me that 1/125 works just fine.

The light from the gridded spot lights up just my face, and you can see there is very little hitting the wall behind me. There is also a small portable flash right behind me - it has the remote to trigger it, and its light triggers the other one. It gives a highlight behind me, and if I still had my big '80s hair or gingerish afro
it would have lit up like a halo.

Notice the window behind me. It's 3 pm, in Phoenix, on a sunny spring day, yet it looks like evening or later out there. Because I am putting so much MORE light down than the stuff outside, even though it is bright to my human eyes, the camera sees it as "less bright" and therefore renders it as "Shadow".