Capturing light trials and producing long exposures of the night sky with slow shutter speeds are a fantastic and brilliant way to learn and begin to understand the functionality of your camera.
We know that when working with slow shutter speeds / long exposures we most likely want to be using a tripod to keep our image steady. An advantage of working on a tripod in low light is that we can reduce our ISO for maximum image quality and lack of noise.
But what do we do if we want to freeze motion? Perhaps you want to capture a tack sharp image of a racing car shooting by, a horse leaping over a fence or anything else that requires us to be able to “freeze” motion. Understanding how to get these pin sharp images is especially important if you're shooting sport images.
By working with substantially faster shutter speeds than you would do to create a light trail you're able to do away with a tripod. After all, your subject is moving quickly and you need to be able to move quickly and adjust your composition to capture that perfect moment.
The downside to shooting at quicker shutter speeds is that we're limiting the amount of time that light has to get through your lens aperture and onto the sensor. The end result can be darker, underexposed images. When working with slower shutter speeds on a tripod we're able to reduce our ISO for minimum noise/grain. The tripod does the job of keeping the camera steady and the image will remain sharp despite the long exposure. In this scenario, we want to increase the ISO to balance correct our exposure. By increasing the ISO of your camera and getting your exposure spot in does mean that you run the risk of increasing the noise in your images. In today's world noise can be reduced and many cameras are capable of maintaining amazingly sharp quality images with minimum noise at much higher ISO levels.
- Experiment with faster and slower shutter speeds and become familiar what you need to adjust to freeze the motion your capturing. Find that sweet spot.
- Don't go from one extreme to the other. You don't need to go to your highest ISO and fastest shutter speed in order to get this right. Increase one then the other in a number of tests that allow you to maintain as much quality as possible. Remember the faster the shutter speed the darker your image will likely be, by taking your ISO straight to the top your actually just maximizing noise increase.