Chasers heavily utilized still photography since the beginning. Videography gained prominence by the 1990s into the early 2000s but a resurgence of photography occurred with the advent of affordable and versatile digital SLR (DSLR) cameras. Prior to this, 35 mm SLR print and slide film formats were mostly used, along with some medium format cameras. In the late 2000s, mobile phone 3G data networks became fast enough to allow live streaming video from chasers using webcams. This live imagery is frequently used by the media, as well as NWS meteorologists, emergency managers, and the general public for direct ground truth information, and it promotes video sales opportunities for chasers. Also by this time, camcorders using memory cards to record video began to be adopted. Digital video had been around for years but was recorded on tape, whereas solid-state is random access rather than sequential access (linear) and has no moving parts. Late in the 2000s HD video began to overtake SD (which had been NTSC in North America) in usage as prices came down and performance increased (initially there were low-light and sporadic aliasing problems due to chip and sensor limitations). By the mid-2010s 4K cameras were increasingly in use. Tripods are used by those seeking crisp professional photo and video imagery and also enable chasers to tend to other activities. Other accessories include cable/remote shutter releases, lightning triggers, and lens filters. Windshield mounted cameras or dome enclosed cameras atop vehicle roofs may also be used, and a few chasers use UAVs ("drones").