Which of the following is essential for avoiding blurry photos during long exposures?

Using a cable release is essential for avoiding blurry photos during long exposures because it minimizes camera shake. When taking a photograph with a long exposure, even the slightest movement of the camera can lead to blurriness. A cable release allows the photographer to take the shot without directly touching the camera, which disrupts stability and can introduce motion blur. This is critical in long exposures, where the shutter remains open for an extended period, making any vibrations or movements highly noticeable in the final image.

Other options, while they can influence the overall quality of a photograph, do not specifically address the issue of camera stability during long exposures. For example, increasing the ISO setting can help in low light but may introduce noise, while a wide aperture affects depth of field and exposure but does not prevent shake. Shortening the exposure time can indeed help avoid blur, but it also reduces the amount of light captured, which may not be ideal depending on the situation. In contrast, using a cable release directly tackles the problem of maintaining stability during those critical moments of the exposure.