Post by mac on Sept 24, 2018 10:14:50 GMT
SEP 21, 2018 7:52 PM PT www.pcworld.com/
Jon L. Jacobi, Freelance contributor, PCWorld. Jon is a Juilliard-trained musician, former x86/6800 programmer, and long-time (late 70s) computer enthusiast living in the San Francisco bay area. jjacobi@pcworld.com
Dash cams are already essential in many countries because of scam artists who try to create accidents so they can sue you. They’ve also proven useful for catching cars flying into buildings, or the occasional meteor, as happened in Thailand and in Russia a few years ago.
But while auto con artists aren’t as common here, recording your excursions is a reasonable precaution to take—especially if you’re driving professionally.
What to look for in a dash cam:
-12-volt power: All dash cams use 12-volt power, and nearly all of them grab it from the auxiliary power outlet (also known as the cigarette lighter). One we know of, the Owl cleverly uses the OBDII connector. Hardwiring kits are available if you want a constant 12-volt supply.
-Battery power: A battery that will keep the camera recording after an accident is important if you want to be sure you record an entire incident when 12-volt power is lost. If run time is sufficient, it also allows you to record for a while with the car turned off. Supercapacitors, though they may sound like an improvement on batteries (in terms of recharge cycles and operating temperatures they are), don't offer much recording after the fact, and increasingly--none at all.
-Continuous looped recording, so you’ll never lose fresh data (Of course, older data will eventually be overwritten.)
Incident recording triggered by impact (G) sensors
-Continued recording when power fails so that you can be sure to capture all of an incident. This requires a battery or large supercapacitor. The camera should have a setting that allows you to set how long the camera runs off 12-volt before shutting down.
-A decently wide field of view: You’ll see cameras with as little as 90 degrees’ field of view, but you’ll catch more of what’s around you if you go for 120 to 140 degrees. Some cameras offer 160 to 180 degree lenses. Note that the wider the field of view, the more fish-eye distortion there is, and more processing is involved to compensate.
-Day and night video recording (night quality is a big variant)
-MicroSD card storage. Pricier dash cams bundle a storage card. Some come with larger cards, and some budget models come without. There are often bundles available with the card. One camera, the Owl opts for hard-wired internal storage.
-GPS: This feature could be the tipping point if you use your captured video to resolve a dispute. GPS should either watermark or embed your video with geographical coordinates,. GPS will also automatically set the time in better cameras.
-Parking monitoring: This simply means running the camera where you're not in the car. We have reviewed cameras (VaVa) that have a battery large enough to monitor the car (at a reduced video frame rate) with the 12-volt turned off. But most cameras require that you hardwire to a constant 12-volt source.
-Dual-channel support: This is what you’ll need if you want to run both front and rear (or interior) cameras, though it’ll involve more cabling (and cost more overall). Only a few models we’ve tested have it: The Thinkware F770 (available on Amazon), for instance, though the rear camera costs an additional $80; and the Cobra CDR 895 D Drive HD (available on Amazon), which gets you into dual-channel video for a measly $200—rear camera included.
Jon L. Jacobi, Freelance contributor, PCWorld. Jon is a Juilliard-trained musician, former x86/6800 programmer, and long-time (late 70s) computer enthusiast living in the San Francisco bay area. jjacobi@pcworld.com
Dash cams are already essential in many countries because of scam artists who try to create accidents so they can sue you. They’ve also proven useful for catching cars flying into buildings, or the occasional meteor, as happened in Thailand and in Russia a few years ago.
But while auto con artists aren’t as common here, recording your excursions is a reasonable precaution to take—especially if you’re driving professionally.
What to look for in a dash cam:
-12-volt power: All dash cams use 12-volt power, and nearly all of them grab it from the auxiliary power outlet (also known as the cigarette lighter). One we know of, the Owl cleverly uses the OBDII connector. Hardwiring kits are available if you want a constant 12-volt supply.
-Battery power: A battery that will keep the camera recording after an accident is important if you want to be sure you record an entire incident when 12-volt power is lost. If run time is sufficient, it also allows you to record for a while with the car turned off. Supercapacitors, though they may sound like an improvement on batteries (in terms of recharge cycles and operating temperatures they are), don't offer much recording after the fact, and increasingly--none at all.
-Continuous looped recording, so you’ll never lose fresh data (Of course, older data will eventually be overwritten.)
Incident recording triggered by impact (G) sensors
-Continued recording when power fails so that you can be sure to capture all of an incident. This requires a battery or large supercapacitor. The camera should have a setting that allows you to set how long the camera runs off 12-volt before shutting down.
-A decently wide field of view: You’ll see cameras with as little as 90 degrees’ field of view, but you’ll catch more of what’s around you if you go for 120 to 140 degrees. Some cameras offer 160 to 180 degree lenses. Note that the wider the field of view, the more fish-eye distortion there is, and more processing is involved to compensate.
-Day and night video recording (night quality is a big variant)
-MicroSD card storage. Pricier dash cams bundle a storage card. Some come with larger cards, and some budget models come without. There are often bundles available with the card. One camera, the Owl opts for hard-wired internal storage.
-GPS: This feature could be the tipping point if you use your captured video to resolve a dispute. GPS should either watermark or embed your video with geographical coordinates,. GPS will also automatically set the time in better cameras.
-Parking monitoring: This simply means running the camera where you're not in the car. We have reviewed cameras (VaVa) that have a battery large enough to monitor the car (at a reduced video frame rate) with the 12-volt turned off. But most cameras require that you hardwire to a constant 12-volt source.
-Dual-channel support: This is what you’ll need if you want to run both front and rear (or interior) cameras, though it’ll involve more cabling (and cost more overall). Only a few models we’ve tested have it: The Thinkware F770 (available on Amazon), for instance, though the rear camera costs an additional $80; and the Cobra CDR 895 D Drive HD (available on Amazon), which gets you into dual-channel video for a measly $200—rear camera included.
