Star-trail photography is a long-exposure capture of the movement of stars as the Earth rotates. After taking a long exposure of the stars, they appear in the photo as streaks in the sky. Because stars are not all white, they might appear to be different colors.
To achieve this effect, you must either do one long exposure or take several shorter exposures that are evenly timed and have minimal space between them. After you've taken those photos, you stack them using photo editing software.
If you do one long exposure and you are using a digital camera, noise can be a problem. If you do an exposure of an hour, it could take up to another hour for your camera to do noise reduction. Imagine waiting for two hours and then realizing you left your camera on ISO 400 or used the wrong aperture or left your polarizer on the lens. You have just wasted two hours. Another disadvantage is that if you do not remember to use a fully charged battery, you could risk the battery dying during the exposure or worse, the noise reduction. However, this is the only way to do it if you cannot turn noise reduction off in your camera.
If you take several exposures with an interval timer and stack them, you have shorter exposures. That allows you to test different settings on your camera. If they do not turn out, you have only wasted a few minutes. It also cuts the wait time in half because you will have noise reduction in your camera turned off. If your battery dies, again, you have wasted less time.
If you are short on time, the interval timer and stacking procedure is the right choice for you. However, that technique does require more ambient light because the exposure times are much shorter. Moonlight is a good light source.
If you are short on light, one long exposure will work better for you because you will be capturing ambient light for a longer period of time. Just make sure you double-check your battery life, camera settings, and ensure that you have removed any filters from your lens.
Levitation photography is a technique used to portray the illusion of a person or thing floating in the air. It is done by taking two photos and merging them. One photo is of an empty scene, and another is of the same scene with the subject propped up on some furniture or equipment that can be removed from the scene. Once you have both of those photos, you merge them in Photoshop and erase the item propping up your subject. Levitation is a fun way to challenge yourself creatively.
Infrared photography is a technique that requires a filter either over the lens or the sensor inside the camera. The filter blocks out visible light and lets in the invisible light on the opposite end of the spectrum. The result is a photo with a red hue, which must have the white balance adjusted.
The unique quality of infrared photography is the light appearance of green foliage from the light reflecting off the leaves. It also darkens the sky and makes the clouds stand out.
Infrared requires full sun. For those photographers who prefer not to shoot in the high contrasts light of full overhead sun, infrared opens up new photographic possibilities. Instead of packing up and going home when the sun comes up overhead, you can do infrared and keep shooting an entirely different kind of photo.
High-Dynamic-Range (HDR) photography is a technique in which at least two (usually three) or more photos of varying exposures are merged in photo editing software such as Photomatix. After they are merged, you can do tone mapping and make adjustments to bring more detail out of the shadows and highlights. Of the exposures you take, one must be exposed for the brightest area, such as the sky. Another must be exposed for the darker area, such as the foreground. You must also include at least one in between. When the camera's metering exposes for the sky, the foreground is too dark. When it exposes for the foreground, the sky is too bright. With HDR, you can make the photo appear more as you saw it with your own eyes, which the camera's sensor cannot do.
Usually you can use a graduated neutral density (GND) filter to tone down the sky and even out the light. However, if you are in a situation where the sky is uneven from a tree line or mountain, the neutral density will cover that area. You might also want to use it if you have left your filters at home, or you are taking a photo that does not include sky, but has very high contrast. An example of this would be full sunlight or inside a building. Sometimes you might want to try it just for a more artistic look.
A panoramic photo is two or more photos stitched together with photo editing software such as Photoshop. To do a panoramic photo, you must take several photos overlapped by at least 30 percent. To create a horizontal panorama, take several vertically oriented (portrait orientation) shots and overlap them across your scene. To take a vertical panorama (or "vertorama"), take several horizontally oriented (landscape orientation) shots and overlap them across your scene. You can also go across the middle, up, and down to do more of a square format.
Panoramic photography has a few advantages. The most obvious advantage is that you can fit large areas into a picture by stitcing smaller ones together. Another reason you might do a panorama is because you may have packed lightly and not brought your wide-angle lens. Panoramic photography allows you to use a longer lens to get more of the landscape in your photo. The other advantage is that the more, smaller photos you take and merge together, the larger resolution photo you end up with. Because the end product has a larger resolution, it can be printed much larger without degrading the quality.
Let's hope it gets good ones soon!