Camera & Lens: How to Get the Correct Match
Surveillance experts say that you cannot separate lens function from camera function — they are complementary and interdependent. Does that make the integrator’s job harder?
Choosing a lens for a camera is not a new skill for integrators who have worked in the video space for any length of time. However, the parameters have changed. Some things have gotten simpler; others are more complicated.
“The lower resolution of analog and VGA cameras is more forgiving of lens selection,” says Frank De Fina, senior vice president of sales and marketing, Samsung Techwin America, Ridgefield Park, N.J. “But using an inferior lens with a megapixel or HD camera can undermine camera (and overall system) performance.”
By their very nature, high-definition cameras require a high level of precision and quality because of the job they have to do, which is to resolve much finer detail, says Brad Witte, vice president of operations for integrator Will Electronics, St. Louis. But when high-definition and IP megapixel cameras began to emerge on the market, there was a lag in the lenses to go along with them.
“Everyone knew cameras have resolution, but many people didn’t realize lenses have resolution as well,” says Brian Karas, director of field engineering, VideoIQ, Bedford, Mass. “In the security camera industry for a very long time we were stuck on standard resolution. Advancements had stagnated and lenses had plateaued. As we started seeing higher resolution cameras, we realized that sensor capabilities were outstripping lens capacities. We had to increase precision and step up the quality so 2 megapixel cameras were getting a 2 megapixel image, not a 0.3 megapixel quality.”
Lens manufacturers were late to the party, but they are catching up now, says Allesandro Gasparini, chief commercial officer, ImmerVision, Montreal.
“You had originally the standard definition cameras and lenses to match that had been manufactured for decades,” he describes. “Then for the past five years, there has been a huge development of IP and HD cameras. The problem was the lenses weren’t there. The lens is like a tire on a car. Imagine a NASCAR car with Toyota Corolla tires. You really need to have a match between the lens and the sensor.”
Chuck Westfall, advisor for technical information in professional engineering and solutions, Canon U.S.A., Lake Success, N.Y., agrees. “The real change that has happened with IP is that resolution has gone up. In the analog days, you were limited to standard definition, which was really not too demanding on the lens. Now with the change to digital, the ability to go to higher resolution is becoming much more of a factor in terms of lens quality.”
In short, the lens matters more now than ever.
Lens Choices Today
It is possible to find cameras with 10 or more megapixels. However, limitations on bandwidth in the large majority of security applications have kept the megapixel choices in the 1 to 3 range and lens manufacturers have responded to that accordingly.
“The gap is closing, but we are not quite there yet,” says lens manufacturer Daniel Davies, OEM and new business development manager, Tamron USA Inc., Commack, N.Y. “A lot of high-end sensors out there have pixel counts up to 10, but very few lenses are capable of providing resolving power that matches that.
“Going into late 2012 and 2013, the 1 to 3 megapixel camera is the core volume in the security industry. For that range, lenses are pretty much available in all focal lengths from wide to telephoto,” he emphasizes.
The 1 to 3 megapixel range is no accident, says Frank Abram, director of sales and marketing, security systems, at Denver-based Pentax Ricoh Imaging Americas Corp. “The reason for that is there is a bandwidth issue for transmission of very high definition pictures. There are also storage issues.”
And the ability to view that resolution is not there yet, either, adds Mark Collett, general manager, Sony Security, Sony Electronics Systems Division, Park Ridge, N.J. “Some manufacturers talk about an 8 megapixel camera and 99 percent of the time that is not the case. The processing on the camera doesn’t make up for the poor quality lens, and the display doesn’t support more than 2 megapixels anyway.”
Jeffrey Stout, director for national integrator sales, Tri-Ed / Northern Video Distribution, a distributer based in Woodbury, N.Y., agrees. “I think there is a huge race by camera manufacturers to get to whatever the next big megapixel is, to get to that next level. But the industry itself has kind of stuck on that 1 to 3 megapixel range. That is where lens manufacturers are starting to bring on all the different variants of lenses you can have. I think most people will tell you that the lens manufacturers are catching up to where the industry is shaking out to.”
Within that range, the shortage of lenses is mostly a thing of the past, and integrators and manufacturers can largely get what they need, if not always everything they want.
“Are there an adequate number of megapixel varifocal lenses? Probably not,” Abram says. “No matter how many lenses the manufacturers come out with, someone in the marketplace wants something different. But the supply is adequate for current market needs. Still, there is not the wide selection that is available in the analog marketplace.”
How Lenses Are Sold
How lenses are being provided in the HD and megapixel space is also different from the analog world. For a long time, integrators were used to choosing a lens (from a wide variety of comparable sources) for a box camera. Then dome cameras and bullet cameras started to come with lenses included and the lens mostly became a non-issue. Not so with higher definition cameras.
“Lens selection is critical for megapixel cameras because with higher resolutions the lens could potentially be a limiting factor,” De Fina says. “Integrators should not make the mistake of choosing an inferior lens for use with a megapixel camera.”
In many cases, they don’t have to choose. Manufacturers such as Pentax, Samsung, Sony, Canon and others provide the appropriate lenses with the cameras, simplifying the choice for the integrator.
Like their analog counterparts, high-definition dome and bullet cameras come with lenses included, narrowing the choices to three or four fields of view or focal lengths that the integrator has to choose from. Box cameras may or may not have included lenses.
“Our box cameras are priced with the lens not included, but can be supplied with Samsung lenses tested to ensure performance and designed to complement camera capabilities,” De Fina offers as an example.
“Today most cameras in the middle range come with lenses included,” Gasparini says. “All mini domes come with the lens because it is packaged together. With box cameras, some vendors include a lens with a certain field of view and coverage, but also allow an integrator to remove the lens and put another in to have a different result.”
Inclusive lenses can be a popular option because it is generally more cost effective and simpler for the integrator.
“It tends to be a more obvious choice with the lens included,” Karas says. “Usually the difference will be in focal length and the integrator really only needs a rough understanding of what they expect the field of view to see. Other criteria would be pre-selected or sorted by the manufacturer.”
This is the way Len Segarra, systems consultant for TEM Systems Inc., an integrator in Ft. Lauderdale, Fla., prefers to do things. “We typically buy the lens/camera package from the manufacturer because we know it will work with their camera. Years ago we had to specify lenses depending on what we wanted to see and eventually everyone went with the 2-12 combo lens,” Segarra describes. “Now things seem to be heading back to specifying the lens for the camera because megapixel cameras give you so much more information. The one-size-fits-all approach doesn’t always work today. We have tried to stay with the lenses from the manufacturer because we know those will give us a certain level of performance. If you buy a camera from company X and put company Y’s lens on there, it may not work right.”
Rick Zimmerman, director of physical security, Netech Corp., a Grand Rapids, Mich.-based integrator, addresses accountability in lens selection. “Things are simpler not having to choose a lens. Truthfully, from a business impact, I really need to hold that camera manufacturer accountable for doing their due diligence on their lens partners. If I have chosen a camera and selected on my own a different lens, it is on me. But if I take guidance on it from a manufacturer and there is an issue, I can go back to them and say ‘this is our problem, not just mine.’”
There is so much to know in the IP world, that relying on a manufacturer or distributor is often the safest way to go, Stout adds. “There are too many things that can go wrong in IP systems. The very first thing you have to get right is lens selection. That is where you determine how well the camera will see what the customer needs to see.”
How to Choose a Lens When You Need One
While many manufacturers are providing lenses designed to work optimally with their cameras, there are still plenty of scenarios that require an integrator to specify, locate and install their own lens in a HD or IP megapixel camera — whether it is a box camera sold without a lens or an application that requires a specific focus or light scenario. This is where things can get sticky.
“The selection of high-quality lenses is both difficult to identify and locate,” Witte says. “Just because someone says they have a 3 or 5 megapixel lens doesn’t mean it is high quality. Not all lenses are created equally. I have seen many rated for a certain megapixel but the corners don’t live up to those specifications.”
One of the reasons for that, Davies asserts, is that resolution and lens specs are measured in different units or definitions from manufacturer to manufacturer. “This is a confusing thing for a lot of integrators,” he says. “It makes it so lenses can’t be compared side by side. Some manufacturers specify the center of the image as their resolution while others (including us) specify corners as the minimum resolution, with the center being higher.”
Integrators need to be especially aware of distortion of the lens at the edge of the image, De Fina says. “Megapixel cameras provide the ability to enlarge any section of an image, including sections at the edges where distortion is noticeable.”
But even if you get resolution specs that say they are at the corners, that can still be misleading, Davies adds, because manufacturers often don’t specify the focal length where that resolution is met.
The best thing an integrator can do is test, test, test.
“We request a demo and evaluate it on the bench and in the conditions it will be used in, if at all possible,” Witte says. “The only true way to evaluate a lens is a shootout. Specs only go so far. And past performance is no guarantee of future results. Just because a manufacturer always made good standard resolution lenses doesn’t mean their HD lenses will be as good.
“Choose a lens based on specs, but verify them by testing. Everyone will be much happier. It will reduce callbacks, installation times and produce a better product for your customer. I don’t want to have to go back on a job because the customer is not satisfied. The easiest thing to do is put a poor quality lens on a good camera. That will take a perfectly fine camera and make it look awful,” Witte describes.
Resolution is key, but there are other important specifications to pay attention to as well, when choosing lenses to evaluate.
“The first thing they need to do is match the lens with the capability of the camera,” Abram says. “If they have a 3 megapixel camera, they should use a 3 megapixel lens.”
It is not a problem to put a higher megapixel lens on a lower megapixel camera, but the reverse can be disastrous. “If you put a 1 megapixel lens on a 5 megapixel camera, you have just dumbed down that camera to a 1 megapixel camera and thrown your money away,” Witte explains.
According to Karas of VideoIQ, there are four or five key criteria for choosing a lens. “First there is the resolving power of the lens itself, which should be equal to or greater than your camera,” he says. “Then you should make sure the lens is rated for the camera’s imager sensor size, usually between ¹⁄³ and ½ inch. Going over is not a problem, but you may pay a little more for the lens. It is a matter of doing the math and realizing how much area this camera needs to cover for its placement. Then there is the aperture, or F-stop. The lower the number, the more light it will let in. But you can go too low. A lower F-stop has less depth of field.
“So lens resolution, sensor size, focal length and aperture are the four main criteria. The fifth is when you are doing outdoor scenarios; most cameras can switch to black-and-white mode at night, allowing the camera to pick up IR light. Lenses with IR-corrected coating allow the camera to focus in both day and night mode,” Karas explains.
The Lens Market Now & Going Forward
“Five years from now people will be buying more megapixel cameras than analog and we will have better lenses,” Gasparini believes. “With an increase in sales of high megapixel cameras, the volume will mean the price will come down and you will have 5-megapixel cameras at half the price of today.”
For an integrator operating in the HD and IP megapixel space today, lens choices can be confusing. However, manufacturers and integrators alike stress that this is just one part of the overall surveillance picture.
“It is a mistake to separate lens function from overall camera function — they are complementary and interdependent,” De Fina says.
“To be truthful a lot of the focus has been on the cameras, but the more significant piece is the back end,” Zimmerman says. “Sometimes there is so much focus on network capacities and redundancies that people have lost sight of image quality. On the flip side you can have perfect imaging but you also have to deliver that content in a stable environment. As I make these decisions I would rather position it as a quality product from end to end.”
Innovation Through the Lens
IR lenses are one of the recent advancements that have improved the market, according to Brad Witte, of Will Electronics. “They are a recent and welcome feature that allows a lens to be in focus in visible light and remain in focus under infrared light.”
Along with this, current lenses have improved optics, lower F-stops, better light transmission and a smaller physical size, adds Frank Abram of Pentax. “I think we will continue to see an increase in the resolution in the future including up to 10 megapixels. I do believe that the resolution of cameras will continually increase and that will be dictated by our transmission methodology. As we go to gigabit networks, the higher megapixel cameras will become much more evident in the security marketplace. As a result, the optics industry will have to meet that with additional higher optic capability lenses.”
Sony is working on a technology designed to improve resolution without taking up more bandwidth, says Mark Collett of Sony Security, Sony Electronics Systems Division. “As the marketplace has emerged, technology originally developed for the motion picture industry has migrated down to security cameras.” The next step, he says, is 4K technology, which will allow for 8-megapixel capability at both the camera and display, while the onboard capability of the camera is doing compression so it is not taking up more bandwidth.
The Big Picture
A trend that is being seen for certain applications is a wide-angle or 360 camera, and there are some unique issues with choosing the right lens/camera combination in those cases.
“There are a couple of challenges,” says Immervision’s Alessandro Gasparini. “The first is the performance of the lens. The other is the compatibility of the solution you are putting together. Most of the traditional lenses are fisheye lenses that come in one size and one mount. When you put them on a camera, you need to have no blind spots. The footprint of the lens needs to fit the sensor size or you will have blind spots. Compatibility-wise, when you use wide-angle lenses they can create distortion, which is not user friendly when you watch it.” Proper software can correct for this, he adds.
Some manufacturers correct for distortion in the lens itself. “Where Canon has strength is even when showing that view, the lines of the subject reproduce very accurately,” says Chuck Westfall of Canon U.S.A. “There is always the possibility of using software to try to correct the distortion issue, but it is better not to have the distortion to begin with.”
When you are buying 360-deg. or wide angle cameras, it is important to be aware of how that distortion is going to be corrected, says Jeffrey Stout of Tri-Ed / Northern Video Distribution.
“You have to watch out for that fisheye effect; 360 lenses vary from manufacturer to manufacturer in how they correct for that. How do they take that image and stitch it together so there is a usable image? You really need to be aware of how the manufacturer accomplishes that and the software that supports it,” he says.