Beginners Guide to edgertronic high speed camera
You have a cool high speed camera. Now what?
You have extensive photographic experience. That's great! You already understand shutter speed, aperture, depth of focus, ISO etc. On the other hand, you may just want to use the camera, but don't understand all that mumbo-jumbo. Either way, this guide will provide a quick introduction to high speed video and how to successfully use the edgertronic camera.
Exposure: An Exercise of Balance
Modern digital cameras use shutter, aperture and sensitivity settings to control exposure. These settings might be automatic in a Point-and-Shoot camera, or allow manual override in a high end SLR. The edgertronic high speed camera provides manual control of these settings, allowing the user to optimize the camera for the task at hand. Most of these settings are tradeoffs: changing a particular setting will improve one characteristic and simulteneously degrade another. Furthermore, these settings often interact with each other. An understanding of these tradeoffs and interactions will help you pick the best balance, of these settings, for your unique application.
Shutter: Light vs Motion
A shutter is a mechanical or electronic device that controls how long light is captured for each frame. For historical reasons, the shutter is specified in fractions of a second like 1/60. The edgertronic has an electronic shutter, and the shutter can be set from 1/10 to 1/250,000. Here's the first trade off you must manage: long shutters let in more light, but short shutters are better at freezing motion and allow higher frame rates.
Aperture: Light vs Depth-of-Field
The aperture is the part of the lens (iris) that can be opened or closed to let in more or less light. Turn the aperture ring and you'll see the iris open and close, admitting more or less light. Apertures are specified in F-stops like f2.8. The Nikon lens supplied with the edgertronic has an aperture range of f1.8 (large iris, most light) to f22 (small iris, least light). Here's the second tradeoff: there's a range of distances where objects are in focus, called Depth-of-Field (DOF). Large apertures like f1.8 let in the most light, but the DOF is very small. Conversely, smaller apertures like f22 let in less light, but the DOF is much larger.
ISO: Sensitivity vs Noise
The ISO rating is a number that indicates how sensitive the camera is to light. In the old film days, different films had different ISO ratings. The films with low ISO ratings were generally sharper and had less visible grain compared to those with higher ISO ratings. The edgertronic camera is electronic, and the ISO rating can be adjusted from 100 - 1600 (color) and 400 - 6400 (monochrome). You guessed it .. ISO is the third trade off. You will get the best image quality at low ISO settings. Higher ISO settings electronically increase the light sensitivity, but also increase noise.
In Summary: You Can't Have Too Much Light
Let's say you are trying to take a high speed video of a baseball being hit. You want to freeze the fast motion, so you'll need a fast shutter setting. You want everything to be in sharp focus, so you'll need a small aperture for good DOF. You want the image quality to be as good as possible, so you'll need a low ISO setting. A fast shutter needs more light. So does a small aperture and low ISO setting. Now, you need a lot of light, far more than you've ever needed. Even daylight may be insufficient.
Why does high speed video require much more light? The simple answer is shutter speed. A normal video might be shot with a 1/60 equivalent shutter speed. The edgertronic is a high speed video camera and you'll rarely use shutter speeds slower that 1/500. In the baseball example above, you might use a shutter speed of 1/3,000. That requires 50x more light (5.7 F-stops) than a 1/60 shutter. That's a big difference. Now turn the shutter to it's fastest setting: 1/250,000. Now you need 4167x more light (12 F-stops). Sunlight might not be enough.