Selecting the best lens resolving power for your camera's pixel size

Selecting the best lens resolving power for your camera's pixel size 
It's crucial to take your industrial camera's pixel size into account when choosing a lens which matches the lens resolution. Line pairs per millimeter, or lp/mm, is used to express the lens resolution. This guarantees optimal performance of your industrial. The concept of lens resolution in line pairs per millimeter (lp/mm) is explained in this article along with how to determine if your industrial camera is compatible.


Pixel size and lens resolution, measured in line pairs per millimeter (lp/mm), are significant factors in digital imaging. You can gauge a camera or lens system's spatial resolution by counting the number of line pairs per millimeter. The physical dimensions of a single pixel on an image camera sensor are referred to as pixel size.

If there is any way we can help you choose a good lens for your industrial camera, please don't hesitate to contact us.

What is the lens resolution?

The quantity of distinct black and white lines per millimeter of image space is known as the number of line pairs per millimeter. The lens resolution is this. The spatial lens resolution increases with the number of line pairs per millimeter (lp/mm). This makes it possible for the industrial camera or lens system to capture images with finer details.

A lens that has a lens resolution of 100 lp/mm, for instance, can resolve up to 100 pairs of white and black lines for every mm of image space. Even at ten microns apart, objects can be distinguished by the industrial camera. This is a theoretical value, the physical performance may vary. Click on this link for a complete overview of our c-mount lens portfolio.

What is pixel size?

The physical dimensions of a single pixel on the image sensor of an industrial camera are known as pixel size. Micrometers, or μm, are used to measure the size of pixels. The resolution of a camera is determined by the total number of pixels. The MER2-160-227U3M camera, for instance, has a resolution of 1440x1080 = 1.555.200 pixels = 1.6MP. You will require a lens with a higher number of lp/mm if your pixels are smaller.

Relationship between lens resolution and pixel size

The following formula can be used to determine the relationship between the lens resolution and pixel size:

ξ = (1lp/(2*s)) * (1000µm/1mm)
with s = actual physical pixel size

For instance, the spatial lens resolution of our 9MP camera (ME2P-900-43U3M), which has 2.5 micron pixels, is 200 lp/mm.

Lens table

Refer to the lens table to determine the lens resolution (lp/mm) that corresponds to the camera's pixel size. For a detailed list of every lens in our portfolio, along with its lens resolution, please visit our Download Page.

Lens series

Minimum Pixel size

Center Pairs (lp/mm)

Edge Pairs (lp/mm)

1/1.8" 5MP

3.45μm

160

125

1/1.7" 12MP

2μm

250

160

2/3" 5MP

3.45μm

160

100

2/3" 10MP

2μm

250

160

1.1" 10MP

3.45μm

160

100

1.1" 20MP

2,5um

200

125

1.1" 25MP

2μm

250

160

4/3" 20MP

2,5μm

200

125

1.1" 12MP Macro

3.45μm

160

100

1.4" 45MP

2μm

250

160

 

Lens resolution in the center vs. edge

The difference between the number of line pairs per millimeter (lp/mm) at the lens's edges and center is displayed in the above table. The industrial camera's image likewise reflects this lens resolution; it is marginally sharper in the center than it is in the corners. The lp/mm of the center is typically used to determine the proper lens for the camera's pixel size.

Recommendations to match a lens with an industrial camera

To match the pixel size of your industrial camera with the lens resolution, or the number of lp/mm, use the lens table above as a guide. In certain circumstances, a lens that has fewer lp/mm than necessary is suitable for the pixel size of your industrial camera sensor:
- When purchasing a lens with a higher lens resolution (more lp/mm) is out of your price range.
- It is necessary to have a very light-sensitive lens with an aperture of F1.8 or less; higher resolution (higher lp/mm) lenses are not available.

A lens with a lower resolution may, under certain conditions, produce an image that is marginally less sharp; nevertheless, this may be acceptable for your intended use. If we can still help you on calculating the lens resolution, kindly get in touch with us.