Across many applications there are hundreds of thousands of low-cost CCTV cameras being installed. The question for end users and integrators, too, is whether this is a problem, or whether some affordable cameras can meet a testable minimum standard when it comes to operational requirements.
THERE’S no doubt that many low-end cameras are low end performers. They exhibit inconsistent performance, they have plastic lenses with curious optical characteristics, their poorly designed CMOS sensors show blooming, depend on amplification to enhance ordinary low light performance and cut corners with compression to tidy up. But not every affordable surveillance camera is the same and there are plenty of options in the mid-range that properly informed end users would be happy to install in many applications.
SEN chatted to a group of CCTV consultants about low end cameras, asking them whether such cameras could offer reasonable performance and if there was an all-round focal length and resolution that could be relied on by installers to handle most general applications.
“My view is that almost any camera will work internally with the availability of consistent artificial lighting to cover small areas – for offices, some retail and in corridors, you can’t go very wrong with them,” says Luke Percy-Dove. “Outside of that, it’s very easy to get camera selection wrong and too many in the video surveillance industry continue to do. I don’t believe the end-user wants low-end cameras most end users will pay a fair price for CCTV if they are properly advised on the differences.
“At the affordable end of the market, domes are the most common choice because they are incredibly versatile. A 3-4MP dome with good WDR capabilities and a 4-12mm lens you could use almost anywhere. Plus, they are robust and less susceptible to tampering.”
CCTV design consultant, Scott Myles, says he finds customers understand the need for security advice “that converts to viable, real-world fit for purpose and future proof solutions – we generally do not work in the lower end of the market, however, from a domestic or light commercial perspective where systems are not mission critical, the lower end of the market offers solutions”.
“As technology develops, we are seeing a shift from the typical single sensor camera application to now multi-sensor both individual and stitched panoramic views, that provide users with enhanced situational awareness,” Myles says. “As camera technology develops, we look forward to the opportunities and benefits that this will bring to our industry and our customers.”
If you’re looking for a standard low-cost camera with a fixed lens, what’s the DoF sweet spot when it comes to focal length and resolution with 1/3-inch sensors? Would you agree 6mm at 1080p with a maximum admissible depth of field up to about 10 metres?
“This is an interesting question and from our experience the answer is more aligned to the application instead of a hard and fast rule around the image sensor and lens type,” Myles explains. “As we all know DoF changes with the light conditions and is dependent on the quality of the lens. As such we generally look at the application and the target area and take into consideration many factors such as object, target size, environmental conditions and motion, and work from there.
“In some circumstances to achieve the desired goal such as license plate recognition from oncoming moving vehicles, has required additional IR illumination to be applied with positive outcomes, and as it is with all our studies the same methodology is applied where we address each requirement based on the requirements.”
Over at CCTV Consultants, Doug Grant argues the obvious problem with low end camera sales is that lower margins on sales have led to a supply industry with far fewer support staff on the ground.
“Business models have changed to manage the lower profits and lower volumes,” Grant explains. “We are in the middle of a change that may end in a monopoly for a very few. At issue is that the cameras in this lower end may not reach certain operational requirements required 5 years ago but they are being accepted by end users as an acceptable image device for their video surveillance solution.”
According to Grant, the first dome camera was made by Elbex of Japan in the early 1990’s and the most common cameras now installed in a low end of the CCTV market are Chinese-made dome cameras – he points out that many other brands are having their cameras manufactured in China in order to compete.
However, Grant is quick to point out that the major Chinese manufacturers make high end CCTV cameras that are the equal to, or of higher quality than their competitors, but he says this has not altered the fact price has superseded operational requirements in too many solutions.
“We are all to blame for it as everybody wants to sell more cameras by offering the cheapest product, rather than educating the customers to make wiser choices,” he explains. “Sadly, this is an outcome of our industry lack of professionalism. In my opinion, the quality of CCTV systems is only debated when something bad happens. Until then, it is only a race for selling more, no matter what quality.
“Regardless of the quality of some benchmark cameras in any manufacturer’s lineup, there are still some inferior items there. I’ve done many detailed evaluations for some consulting projects in the past year or two, and I know this is true and installers and end users should be aware of it. Each camera model, no matter what make it is, should be independently evaluated by a knowledgeable technical person.”
While Grant agrees domes are the most common camera type being installed, he says he prefers full body camera types, which allow lens replacement.
“Having said this, many vari-focal lenses, although inferior to good fixed focal lenses, have sufficient quality to be used in a variety of applications,” he explains. “But there are some models where the camera electronics are very good, but the lens quality is poor, and when combined and added with dome (bubble) reflections and distortions, they make a poor choice for many applications.”
Vlado Damjanovski of ViDiLabs says that installers looking to use low cost cameras with fixed lenses in typical applications to take advantage of the area of sharpest focus could use a quality 1/3-inch HD sensor with a lens focal length of 6mm, but he says they’ll still need to be mindful of their application.
“This combination would give a hyperfocal point of around 2m in front of the camera (this is your actual focussed plane), but the image will appear sharp from 1m in front of the camera to infinity – that’s what gives you depth-of-field,” Damjanovski says. “Using a camera like this in a suitable application would mean you would not need to re-focus the camera if the object moves from 1m up to infinity.
“Having said that my ViDiLabs calculator explains that with the 1/3-inch HD lens and 6mm fitted, your ability to identify faces according to our standards (350pix/m) will only be up to 7m. Faces that are further then 7m will appear smaller (they’ll have less pixel density) and will get harder to identify. This will be especially noticeable when it gets darker, as the resolution reduces with increased noise. Given this, I would argue that depending on the camera quality and noise compression, the calculated 7m will become less when it gets darker.
“So, with your example installers will have an image which is supposed to have quite a good DoF, but when noise kicks performance will fall away. I would argue that bigger pixels would be much better choice, even if I don’t have such a DoF. The DoF does depend on the pixel size. With bigger pixels, the DoF for the same f-stop is shallower. So, we do get a bit of benefit using smaller pixels which produce bigger DoF, but the picture gets noisier.”
Damjanovski says iris setting is another consideration installers will need to keep in mind during installation – the aperture that produces the sharpest image is not the largest aperture but is always several stops down.
“The sweet spot in optics usually refers to the iris setting which produces the sharpest overall image,” he explains. “The iris sweet spot does not provide the highest depth of field (DoF), but it provides for sharpest optical image at the focal plane for the given lens. Typically, the iris sweet spot is in the middle of the lens F-stop abilities, and this is used by the so-called P-iris technology, where camera electronics attempt to keep the iris in the sweet spot as much as possible for the given light levels.”
#securityelectronicsandnetworks.com
