A physiogram is a single long exposure of a flashlight spinning around on a string that is tied to a ceiling. You heard me, simply find a way to attach your flashlight to a string or shoelace or something, then put your camera on the ground with the widest angle you can get (after getting the light in focus, then switching the focus off), turn out the light, turn on the flashlight, give it a good push, then take a long exposure of the physiogram. You can also achieve different kinds of effects by zooming in and out, or focusing in and out while the exposure is taking place. You can also use different colored lights, and blend them later in Photoshop. When you take the photo, I recommend using a 30 second (the maximum shutter time on most DSLR cameras, unfortunately) exposure, or, if you have a BULB mode on your camera, you can use that.
Examples of Physiography:
This last image was manipulated later on a computer.
You could theoretically create a physiogram with a sparkler too. Yep, a firework SPARKLER. How awesome would that be? I haven't done it before, however the idea would be to put your camera on the ground facing upwards underneath some protective glass. Tie the sparkler to a tree branch, weight it down somehow, and take the shot the same way you would take a regular physiogram.
You could also use a tripod pointing down at a mirror, with the light source above the mirror. This way you would capture the reflection, and you would be able to see through your viewfinder. I like using a wide angle lens and just putting my camera on the ground and taking the shot, however.
If your in a highschool photography class, this will totally flip people out. Most, if not everyone, will not know how you did it. At least that's how it was when I did it in highschool.
The Maglight Solitaire Flashlight is a neat little light that enables the head to be taken off, so it can be in "candle mode". This is great for physiograms and also any kind of light painting. You will definitely have an advantage when using it. You can easily change the colors later inside of Photoshop, or some other picture editing program by adjusting the Hue/Saturation and/or by creating a new layer with the blend mode set to Color, and then paint on that layer using a color brush.
Drawing with light is extremely easy and fun. Simply wait until night time, put your camera on a tripod, and set your exposure for long periods of time (these are usually 5 seconds-5minutes), your aperture, and ISO. I usually use f4 at iso 200 or 400, but these settings need to be determined differently according to each situation. Then, DRAW! There are many different light toys that create different effects. Things that have been used before include sparklers, glow sticks, flashlights, maglights, fire/torches, RGB strips, Christmas lights, illuminated cell phones, iPods, laser pens, and of course, any kind of LED.
If you are interested in incorporating long exposure effects and light painting into your night photography, I would highly recommend "Night Photography & Light Painting" by Brent Pearson, especially if you are light painting landscapes.
Long Exposures During Day
You can also create long exposures of landscapes during they DAY by using an extremely dark filter that attaches to the front of your lens. The filter you can use is a B+W filter, an ND400 filter (I'd recommend this one), or even an Infrared filter. Taking long exposures during the day is useful for creating foggy/ghostly seascapes, blurring clouds, blurring water and waterfalls, and even removing people from a scene (if they are constantly moving).
These are a great challenge, and the best part is, you don't know what the photograph will look like until after you've taken it. You will need to have your camera on a tripod, manually focus to infinite, use the widest aperture you can and a low ISO. If you want to take 20+ minute long exposure, you will need to buy a cable release made for your specific DSLR. However, taking super long exposures can cause a lot of noise in images. An alternative wave to doing star trails is to take a bunch of 30 second exposures and then overlap all the images on your computer using a program called Startrails. There is a minor drawback to this method: for every 30 seconds of an exposed photo, there is a 1-2 second time period where the camera isn't taking an exposure. This makes it so there are little tiny spots not visible in your star trail. It is a very minor drawback, but ultimately it is a better method because there isn't as much noise.
Other Fun Long Exposures
There are also other things you can do with long exposure photography. Long exposures during the day allow water and clouds to blur, leafs on a tree will also blur (if there is wind). In addition, you can also take a long exposure in a very crowded city where lots of people are walking, and completely make the crowd invisible by taking a long exposure during that day.
You can also use a long exposure and then fire multiple flashes to light your subject in different ways, and/or to multiply them in number. You can also spin your camera to take perfect straight blurred out lines, or you can zoom in and out with your lens while the exposure is taking place.
Long exposures also come in handy during lightning, simply take a long exposure and wait for the lightning to show up.
The challenge: create a long exposure that has all of the above. Light painting, light spraying, star trails, and lightning; all in one photograph. (Okay, I realize it would be hard to get lightning, but try to include them all if you can 😉
Because long exposure photography is such a large topic, there is only so much I can write in a blog post. If you want to know more information on lights, techniques and effects, check out my Trick Photography and Special Effects eBook. It has over 60 pages of content solely dedicated to light painting techniques and long exposure effects.