White papers

The trade-off between image resolution and field of view: the influence of lens selection

Image resolution tradeoff

“I want a lens that can cover the whole parking lot and I want to be able to read a license plate.” Sound familiar? As a manufacturer of wide angle lenses, Theia Technologies is frequently asked if we have a product that allows the user to do both of these things simultaneously. And the answer is ‘it depends’. It depends on several variables - the resolution you start with from the camera, how far away the subject is from the lens, and the field of view of the lens. But keeping the first two variables constant, the impact of the lens field of view becomes clear. One of the important factors to consider when designing video surveillance installations is the trade-off between lens field of view and image resolution.

How to calculate image resolution

Parking lot surveillance

The detail in an image is determined by resolution. The shorter the lens focal length, the wider the field of view. Greater than about 90° most lenses start to show curved, barrel distorted images that compress the image at the edges. Rectilinear lenses such as those using Theia Technologies' Linear Optical Technology® don't exhibit barrel distortion and thus maintain image resolution out to the edge of the image.

Improving Image Resolution with Wide-Angle Lenses

Theia Technologies provides a detailed explanation on how users can avoid falling for one of the many marketing hypes out there. Also, this article (A&S Jan. 2014) explains in detail the benefits of using a rectilinear lens and how users can utilize wide-angle lenses to their advantage in suitable environments.

Despite inflammatory media accounts proclaiming the end of the megapixel race in the security industry, recent conversations with camera OEMs suggest otherwise. In fact, camera companies appear poised to up the ante and are moving forward with plans to increase camera resolution, following the lead of cellphone and digital camera companies before them. 

Key considerations in lens selection

SL940 focal length comparison

What should be considered when selecting a lens for a particular application?  Far more than just the field of view.  Other considerations include the lens resolution.  A megapixel lens and camera can improve the detail that can be recorded but increasing the field of view to cover a larger area will decrease the detail.  There are tools available to demonstrate this effect and to help end users and installers avoid the "CSI" effect of infinite zoom-in and enhancement.

Also consider things like day/night, f/#, and lens/camera resolution compatibility. This paper discusses the issues that should be considered when specifying a lens for a particular application.  

Why do you need a megapixel lens?

It's an exciting time in the security department. You've finally received approval to migrate from your installed analog cameras to new megapixel models and expectations are high. As you get together with your integrator, you start selecting the cameras you plan to install, looking forward to getting higher quality, higher resolution images and, in many cases, covering the same amount of ground with one camera that, otherwise, would have taken several analog models. You're covering the basics of those megapixel cameras, including the housing and mounting hardware. What about the lens?

Translated into Russian Что такое мегапиксельный объектив и для чего он нужен

Day/Night demystified: Understanding Day/Night cameras and lenses

...those cameras considered true day/night can physically switch the IR filter out of the light path allowing the camera to see both naturally occurring and artificially created IR light. These cameras require day/night lenses to keep the scene in focus both day and night. Day/night lenses are generally more expensive because of the added complexity of focusing a broader color spectrum (from visible through IR) onto the sensor.

Case study: Theia and Arecont secure high school hallway

Arecont Vision and Theia have delivered an undistorted, detailed view of a Salem, N.J. high school's hexagonal hallway. The megapixel cameras by Arecont, and the wide angle lenses by Theia provide school administrators with a clear view of the school's three wings.

...The solution came by combining megapixel cameras from Arecont Vision with wide-angle lenses from Theia Technologies. Merging the capabilities of both technologies enabled the high school to significantly reduce the number of cameras it needed, and to get superior images in the process.

Eliminate distortion in wide angle images

Today’s megapixel cameras have many advantages as long as you have the right lens for the job. When that includes covering large areas or reducing cost by installing fewer cameras, that lens is a wide angle lens. Until recently only fisheye lenses were available for an ultra wide field of view. Fisheye lenses create a curved and distorted image which no one seems to like. This significant distortion causes loss of resolution at the image edges.

In the past year a new rectilinear lens giving a different ultra wide view without the barrel distortion or loss of edge resolution of fisheye lenses has been developed. This report is an overview of wide angle lens technology and how we overcome fisheye distortion using Linear Optical Technology®.

New lens technology enables better school security

...Despite the limited budgets of so many state and local governments across the country, communities are finding ways to upgrade their security systems and use the latest technology to support their security plans. Upgrading to security systems using megapixel IP cameras with ultra wide angle lenses can be cost effective by reducing the number of cameras to be installed and maintained and eliminating cabling and DVRs without sacrificing video surveillance area.

One example is the Murrieta Valley Unified School District. At one of the district’s high schools a security system upgrade will remove all 170 existing analog cameras and replace them with just 43 IQeye megapixel cameras with ultra wide angle lenses from Theia Technologies.

Theia Technologies' megapixel ultra wide low distortion lenses

Theia Technologies was started along with Japanese manufacturing partner Nittoh Kogaku KK. Nittoh Kogaku is a well respected lens manufacturer with plants in Japan and Indonesia...

Theia Technologies has introduced the world's first ultra wide rectilinear lens for the security and machine vision markets. Theia's proprietary Linear Optical Technology® allows the design of ultra wide angle lenses with fields of view of up to 135° while almost completely eliminating barrel image distortion. Straight lines remain straight in the image. Distortion correction is achieved optically in the lens; no additional de-warping software is required, allowing.