A little light-painting

vase light painted with a pen light for 30 seconds

I did my first light-painting with Sports Illustrated and National Geographic photographer Dave Black some years ago, and it got me hooked! The basic premise is that you photograph a subject in the dark, and you use a long exposure and a mobile light source to 'paint' light on the subject. It sounds simple, but it's very exacting! And quite fun. So here's the How To, along with some of the photos I've created over the years.

Use shadows creatively or back light translucent subjects

What you'll need:
A camera with manual controls that lets you change the shutter speed to 30 seconds
A small, low-power flashlight, or penlight. One of those that goes on a key ring works, or you can use the link to purchase a pen light from me via Amazon (that's what I use)
A completely dark room
A subject
I usually use a plain black or white cloth or paper background, but you can use anything (although I don't recommend a glossy surface, unless you want to use it as part of your effect). When I'm using paper I usually tape it to the wall, making sure not to ruin the paint or wallpaper! 

A unique Christmas card, with decorations we had in the house Use different backgrounds and surfaces
Use a hobby to give you ideas for scenes  

As far as subjects are concerned, if you're working at home, then you're going to want something that fits on a table top. I look for things that aren't going to be too reflective, and along with using a single item, you could create a whole scene. For example, a bouquet of flowers, vases, a baseball mitt, bat and ball, etc. Your imagination is the only thing stopping you here!

How to:
Set your camera: Shutter Speed 30 Seconds, ISO 400, F11
Your camera should be on a tripod
With the lights in your darkroom on, you should set up your camera the way you would if you're photographing any scene. Consider the height of your tripod, the focal length of your lens and the perspective for the scene you're photographing. 
Focus your camera on your subject, then SWITCH OFF AUTO FOCUS. (If you don't, your lens will 'hunt' for focus in the dark and you'll have to start over).You may also want to switch off your lens Vibration Reduction system if your lens manufacturer recommends it while using a tripod.
Carrying your flashlight, now's the time to turn off the room lights, and with your flashlight on, move back to your camera. 
Now, place your finger on the shutter release and switch off your flashlight.
Next, push the shutter release.

Here's where the fun begins. You have 30 seconds or less to use your flashlight which you switch on just after activating the shutter, to paint light all over your scene or subject. Get creative. Where you shine the light is what will be seen in your image. Keeping the light in one place longer will obviously make that area brighter than other areas. Do you want to do that in some areas and then move the light rapidly over other areas? It's up to you. 
Spend more time in one area to bring attention to it, then use the remaining time to fill in the shadows in other areas. That's an option. Remember, objects will create shadows, too. Do you want to see those shadows? Are those shadows putting part of your scene literally in the shade? If that's what you want...great. If not...well, it's do over time.

Here's where it gets interesting. Once your 30 seconds are up, you'll want to look at the image you created once it pops up on the camera screen and see what you want to change to create a better image next time. Now here's the challenge, to do that, you'll need to remember what you just did. Where did you put that light, and for how long? Because if you want something better, you need to change it next time around!
I usually count out how long I'm keeping the light in one place and try to remember where I pointed that light, and from which angle! Use the photo you just created for clues. See where it's too bright and spend less time there. If an area is too dark, spend more time there. You can also move the light closer or further away. Remember that there's a direct correlation between how close a light source is to the subject and how much light falls on the subject (the Inverse Square law), but also remember that moving the light closer or further away will change the shadow too!

All this is why I find light-painting fun and challenging. Every image you create can be enormously different. You can move your subject around, and move your camera around and get a completely different look, but remember every time you move anything, you'll need to switch the lights back on and refocus your camera.

Want to get ambitious? Take it outside! You'll need much more powerful lights!

Some things to consider:
Don't knock your camera or tripod at any point after you've set your focus. 
Don't put your flashlight directly in the field of your scene or the light will appear as a white streak. Of course, there is a version of light painting that does this, and it can create a good effect, so if it's something you want in your photo it's ok. Just don't do it accidentally!
You may want to do a test on which White Balance to set for the light you're using. Otherwise, shoot in RAW or use Auto WB
Don't be afraid to use your post processing editing skills to enhance the image you create.
It's ok to vary the aperture and ISO once you've established a baseline for your exposure becasue different lights will have different power, and your scene may need a larger or smaller depth of field.
Translucent objects like leaves and glass are interesting when back lit.

You may consider shooting tethered to a laptop or pad so you can see more detail in a larger image.

So that's it...I've spent hours in a dark room, 30 seconds at a time, using this technique, so have fun and get creative!! If you get ambitious, you can take the same technique outdoors and choose some more challenging subjects. Just don't get arrested :)!!

You could get really ambitious and light paint a barn in the Grand Tetons!