Camera Specifications: Fact Or Fiction
It was a bloody good question. If non-existent levels of ambient IRE get lumped into the mix how do we know what the minimum scene illumination of cameras should be in the real world in typical applications?For a start, quoting IRE figures allows manufacturers to pare down minimum scene illumination and as part of what can best be described as the ‘claimed specification-driven electronic security culture’ currently holding sway, such contrived specs can make a sale. It’s not just minimum scene illumination, either. You could raise similar issues with horizontal resolution. What’s fascinating to me is the fact many very low-cost cameras claim big horizontal res numbers while using outdated Sony HAD CCDs that in past lives delivered 150 lines less resolution than now magically seem to offer. How can this be? The honest answer is that it can’t. After 20 years observing the electronic security industry and its marketing strategies it seems to me that quality manufacturers find themselves in a trap when it comes to the paper specs being rustled up by a rush of low-cost imports. Is it possible to build a $50 dollar camera with 540 lines horizontal resolution? We don’t think so. But how can you know for sure? As always, the only way to be certain is to go for quality cameras from reputable manufacturers or to spring the bucks for independent testing of 3 or 4 cameras you like the features and prices of, and to then stick with those brands. For installers wondering about the reality of minimum scene illuminations, we’d be looking for an ambient scene illumination of around 100 lux for a speed dome camera. If the unit has day/night capability then around 30 lux could be usable in the immediate vicinity but you’d need to look at issues like presence of smoked polycarbonate domes. There’s also the thorny business of zoom lenses. Once you start using a zoom lens, those miniscule minimum scene illumination numbers with their impossible F-stop designations the manufacturers love to quote go straight to hell in a handbasket. A Bosch AutoDome, Pelco Spectra IV or a Panasonic SD3 has an enormous depth of field once the zoom is applied. Given the camera can readily peer out into the unlit reaches of a site, quoting a minimum scene illumination for a dome with a 30 or 40x optical zoom and a DoF greater than 1000 metres is problematic at best, as honest manufacturers will readily tell you.Meanwhile, at the bargain end of town, unscrupulous manufacturers have another trick to improve low light specs. They claim image streams builtusing half a video signal represent usable surveillance performance. This islaughable and demonstrably untrue. Installers and end users need to come at the dilemma of unproven camera performance in this way. All quality manufacturers are obliged to primp their numbers to outshine low-cost imports whose unscrupulous marketing departments ham it up using the specs of the current best-in-show. At the moment that’s probably Bosch’s Dinion range. If you look at the current pick of the crop from makers like Panasonic, Sanyo, Bosch, Siemens, Sony (and others I’ve forgotten but will shortly be reminded of), the electronic security industry has never been offered such powerful camera technology at such competitive prices. Brilliant fixed cameras for less that $300? Benchmark speed domes for $1800? They’re out there. Against this backdrop of superb performance, the CCTV industry has never been so competitive and as thinking people know, competition is a double-edged sword. Given there are no industry standards that requiremanufacturers to tell the truth, the onus is on installers and end users tofind it for themselves. As a general rule, if you buy or choose a camera with a price that’s far too good to be true then there’s probably only one conclusion. You just bought a camera that’s far too good to be true.