1.What is the Linear Optical Technology?

Linear Optical Technology® is a patented optical design innovation that corrects the fisheye (barrel) distortion that is inherent in wide and ultra-wide angle lenses. The resulting lens is called a rectilinear lens – it keeps straight lines straight and removes the fisheye look. Learn more about our family of ultra wide angle no distortion lenses.

2.What is the Fisheye or barrel distortion?

Fisheye distortion is another term for barrel distortion – the rounded, curved image you see when using a wide-angle lens. Lines at the edge of the image that should be straight will appear curved. A fisheye lens can image a full hemisphere or more, creating a round image on your camera. Learn more about Theia's patented technology that corrects fisheye or barrel distortion optically.

3.How is the resolution is defined and calculated?

‘ Resolution' has many definitions including:

The number of pixels (vertical lines or total number of mega-pixels) in the sensor

The level of detail a lens/camera combination can capture usually expressed as line pairs per millimeter (lp/mm) or MTF (modulation transfer function)

The required number of pixels across an object (a person or a letter/number), is usually expressed in pixels/m.

A more detailed discussion can be found in the white paper “ resolution calculation”.

4. What is IR correction ？ Do I need an IR corrected or a Day/night lens?

Many cameras use near-infrared (IR) illumination from LEDs around the lens or separate IR lights to light a scene at night or for special IR-sensitive applications. This IR light is invisible to people so it is useful for stealthy illumination of a scene, or finding defects not visible to the human eye. However, it may also require the camera to be “day/night” capable (the “night” being tuned to see the IR illuminated scene) and the lens must be IR corrected (also known as ‘day/night'). Using IR light makes the scene brighter for the camera at night but makes color rendition very inaccurate so most cameras with a “night” mode will display the image in black and white. More information is available from the white paper “Day/night demystified”.

5.How do I select a len for my application?

There are many variables that must be considered when choosing the correct lens for your camera and application. Generally, people start with the lens field of view which is directly correlated to lens focal length (for a given sensor size). This determines how much you can see.

Next, there is lens resolution, which should match or exceed the sensor resolution. And for wide-angle lenses, how much lens distortion is acceptable? This determines how well you can see. The higher the resolution, the more detail in the image and the easier it will be to pick out a person or license plate or barcode from a given distance.

Beyond that, lens selection is guided by your application and could include f/# (how much light is required for an image), mount style (C, CS, M12, etc.), motorized zoom/focus/iris, visible/IR light correction, physical size and of course lens cost.

Theia provides a helpful tool for exploring the interaction between field of view, object distance, and resolution in our “image resolution simulator and lens calculator”.

6. How do I select the right lens for my application?

Theia offers a wide selection of lenses from wide angles without distortion using our patented Linear Optical Technology® to telephoto and in between. You can narrow down your selection.  

7.Does Theia offer any lens accessories?

Theia offers motor control boards for our motorized lenses, filter mount adaptors, and set screw kits for many of our lenses.