Frequently Asked Questions

Edmund Optics offers a wide selection of fixed focal length lenses, also called FA (factory automation) or prime lenses, in many different focal lengths options, for different sensor sizes, and in a variety of types with additional machine vision utilities.

The TECHSPEC C Series Fixed Focal Length Lenses is the flagship family versatile and adjustable imaging lenses designed for compact use in most machine vision applications and features focal length options from 3.5mm to 100mm. This family of lenses is also available in a wide range of other useful versions. The TECHSPEC Ci Series Fixed Focal Length Lenses are mechanically simplified and streamlined versions of the C Series that are industrially ruggedized for instrumentation integration. The TECHSPEC Cr Series Fixed Focal Length Lenses are stability ruggedized versions of the C Series with all optical elements glued in place and featuring a C-clamp focus ring for reduced pixel shift and improved focus stability. The TECHSPEC Cx Series Fixed Focal Length Lenses are modular and have flexible mechanics for integrating accessories such as liquid lenses, fixed apertures, and more. The TECHSPEC Cw Series Fixed Focal Length Lenses are IPX7 and IPX9K waterproof versions of the C Series.

Additional fixed focal length lenses adjacent to the C Series family include the UC Series (ultra-compact), designed for ≤2.2μm pixels, the 2/3” and 1.1” HP Series (high-performance), and the CA Series for APS-C format sensors. All fixed focal length lenses at Edmund Optics can be found here.

Imaging lenses feature a wide variety of lens mounts, all of which offer different benefits. For a more comprehensive breakdown of these types and what they are useful for, read Lens Mounts. The most common mounts used in machine vision are the C-Mount, S-Mount (M12 mount), F-Mount, TFL-Mount, and TFL II Mount. The C-Mount, S-Mount, TFL-Mount, and TFL II Mount types offer robust stability for machine vision systems whereas the bayonet-style mount of the F-Mount lends itself better to non-industrial, photography-type applications. However, the most useful mount type depends on the size of the machine vision camera sensor being used as well as the optical abilities of the imaging lens.

Edmund Optics offers a series of TECHSPEC® Double Gauss Imaging Lenses optimized for electronic imaging applications that use high-resolution cameras. They use a modified basic double gauss lens design in order to create a high-performance multi-element lens that will exceed the performance of typically available fixed focal length lenses. The symmetrical design corrects for many optical aberrations, including a distortion that is kept below 0.3%. Conventional lenses often use the same designs that were originally used for photographic objectives. A typical ½" CCD high-resolution monochrome camera (like the Sony XC-75) has a cut-off resolution of 55 lp/mm. Even when focused at infinity, our Double Gauss lenses will have a better resolution than the camera. Their expanded performance yields image resolution greater than 100 lp/mm. After inspecting the MTF curves for 50mm lenses at f/4 and a 400mm working distance, our Double Gauss lens has a much higher contrast (70%) than a typical fixed focal length lens (35%) at 55 lp/mm.

Our TECHSPEC® Double Gauss Imaging Lenses provide high-performance, support large sensor formats, have low-profile compact housings, and an exceptional value. We offer two series of these lenses, Fixed Focus and Focusable. Focusable versions have set screws to lock both manual iris and focus rings in place. Lens Prescription Data is available for qualified optical designers.

The TECHSPEC^® CA Series Fixed Focal Length Lenses feature a TFL Mount and have been designed specifically for new large sensor formats.

A telecentric lens is a video imaging lens that optically corrects for perspective errors due to parallax. Telecentric lenses yield constant magnification over a range of working distances, virtually eliminating viewing angle error. Objects in the field of view of a telecentric lens maintain their perceived size no matter where they are located. These lenses are widely used in machine vision systems that require accurate measurements of three-dimensional objects with slight height variations. By eliminating the perspective errors and magnification errors inherent in conventional lenses, telecentric lenses yield dimensionally accurate images that are easily interpreted by software. For a more detailed look at telecentric lenses, view The Advantages of Telecentricity.

Edmund Optics^® offers Liquid Lens Telecentric Lenses with Primary Magnifications (PMAG) of 0.15X, 0.24X, 0.37X, and 0.75X. You can find more information on the product family page.

Yes, we can make customized Liquid Lens Telecentric Lenses tailored to your specific application. For more information, please contact our application support engineers.

Yes, we can integrate liquid lenses into other types of lenses as a custom request. We also offer the modular Cx Series Fixed Focal Length Lenses, in which you can integrate interchangeable accessories including liquid lenses, fixed apertures, and internal filter holders.

Since we have not tested the other two lubricants that you mentioned (mineral oil and lithium grease) on our VZM™ Imaging Lenses we cannot say what they will do. We use a combination of brass and metal material to hold the optics, so there should not be a major problem with using either of those two lubricants. However, there is still the possibility of corrosion or deposition.

To be safe, using the lubricant originally used on the VZM™ lenses - NYE NYOGEL 779 - would be the best option. We recently looked inside the lens tube of one of our VZM™ lenses and could not see any issues with corrosion on the internal workings.

While there are different types of colored filters that will work for imaging applications, generally colored glass filters or films are the best choice. Dichroic color filters are not typically recommended for imaging use. The color separating that is done by dichroic filters is angularly dependent. As the angle of light coming into the filter increases from the filter's center, the colors that the dichroic filter transmits shifts from the design wavelengths. The effect is that light in the center of a red filter will pass through as red, but light at a large angle (i.e., at the edge of the filter) may pass through as orange or even yellow.

What you are describing is a common issue people have when removing IR cut filters from cameras to do IR photography. Mainly, it is assumed that since the filter itself seems to have no optical power then removing it will have no effect on focus. This is not the case because even though the filter is has no optical power, it still changes the optical path length by refracting incident light. This in turn changes the point of focus. The problem can be easily corrected by simply replacing the filter with a clear piece of glass that is transmissive in the NIR such as BK7 or Fused Silica. It is important that this piece of glass be roughly the same thickness and index of refraction as the filter glass to simulate its optical effects without taking away from the IR performance of the camera.