Lenses Archives - 1stVision Inc. - Machine Vision Articles

June 4, 2025June 4, 2025

Collimated lighting important with telecentric lens

LTCLHP Collimated Light – Courtesy Opto Engineering

Machine vision practitioners, regardless of application or lens type, know that contrast is essential. Without sharp definition, features cannot be detected effectively.

When using a telecentric lens for precision optical 2-D measurements, ideally one should also use collimated lighting. Per the old adage about a chain being only as good as its weakest link, why invest in great lensing and then cut corners on lighting?

WITH collimated light expect high edge definition:

The cost of the light typically pays for itself relative to quality outcomes. Below see red-framed enlargements of the same region of a part being imaged by the same telecentric lens.

The left-hand image was taken with a conventional backlight – note how the light wraps around the edge, creating “confusion” and imprecision due to refracted light coming from all angles.

The right-hand image was obtained with a collimated backlight – with excellent edge definition.

Conventional backlight (left) vs. collimated backlight (right) – Courtesy Opto Engineering.

It all comes down to resolution

While telecentric imaging is a high-performance subset of the larger machine vision field in general, the same principles of resolution apply. It takes several pixels to confidently resolve any given feature – such as an edge – so any “gray areas” induced by lower quality lighting or optics would drag down system performance. See our blog and knowledge-base coverage of resolution for more details.

Collimated lighting in more detail

Above we see the results of using “diffuse” vs. “collimated” light sources, which are compelling. But what is a collimated light and how does it work so effectively?

UNLIKE a diffuse backlight, whose rays emanate towards the object at angles ranging from 0 to almost 180°, a collimated backlight sends rays with only very small deviations from perfectly parallel. Since parallel rays are also all that the telecentric lens receives and transmits on to the camera sensor, stray rays are mitigated and essentially eliminated.

The result is a high-contrast image which is easier to process with high-reliability. Furthermore, shutter speeds are typically faster, achieving necessary saturation more quickly, thereby shortening cycle times and increasing overall throughput.

Many lights to choose from:

The video below shows a range of light types and models, including clearly labeled direct, diffuse, and collimated lights.

Several light types – including clearly labeled collimated lights

[Optional] Telecentric concepts overview

Below please compare the diagrams that show how light rays travel from the target position on the left, through the respective lenses, and on to the sensor position on the far right.

A telecentric lens is designed to insure that the chief rays remain parallel to the optical axis. The key benefit is that (when properly focused and aligned) the system is invariant to the distance of the object from the lens. This effectively ignores light rays coming from other angles of incidence, and thereby supports precise optical measurement systems – a branch of metrology.

If you’d like to go deeper on telecentrics, see the following two resources:

Telecentric concepts presented as a short blog.

Alternatively as a more comprehensive Powerpoint from our KnowledgeBase.

Video: Selecting a telecentric lens:

Call us at 978-474-0044 to tell us more about your application – and how we can guide you through telecentric lensing and lighting options.

1st Vision’s sales engineers have over 100 years of combined experience to assist in your camera and components selection. With a large portfolio of cameras, lenses, cables, NIC cards and industrial computers, we can provide a full vision solution!

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June 4, 2025June 4, 2025

HCN130x0 Hypercentric Nano lenses for cavity inspection

Nano hypercentric lenses designed for the inspection of small cavities and hollow parts with diameters from 0.75 to 10 mm. That’s the diameter of a drinking straw – and narrower!

HCN13010 and HCN13040 Nano Hypercentric lenses for small cavities – Courtesy Opto Engineering

Hypercentric lenses once more with feeling

Recently we introduced Opto Engineering’s HC hypercentric 360° lenses. They image cavity interiors from the outside by utilizing a specialized optical path that allows light to pass through bottlenecks and narrow openings. The variable iris provides maximum flexibility and a wide viewing angle to clearly image the fine details of the object. Their unique design facilitates complete internal surface inspection with no need to use a probe, rotate the object or use a complex multi-camera system.

HC 360° Series applications across whole lens family

HCN Hypercentric nano lenses inspect tiny cavities from the outside

Consider cavities as small as 0.75 mm (0.029 in) ranging up to 10 mm (0.39 in), for items in the order of a drinking straw diameter (and smaller). These interiors can be inspected from the outside looking in, with the HCN Series lenses.

2 minute overview of lenses for hollow-part inspection – Courtesy Opto Engineering

March 14, 2025March 26, 2025

Considerations in using an F-mount vs. a threaded mount

For machine vision purposes, we generally advise against using F-mount. We don’t have a dog in the hunt for leisure or artistic photography, but for reliability in many machine vision applications there are shortcomings with F-mounts.

EMERALD series F-mount lens – Courtesy Schneider Optics

Even our premier partner Schneider Optics, produces very fine F-mount lenses – the optics are first class! But just as a reliable auto dealership would counsel against buying a compact sedan to tow a heavy boat, we would hope to engage you in dialogue about your imaging application – and help you choose the best lens.

There are many lens mounts available

The wide range of lens mounts is, generally speaking, a very good thing. It permits camera designers and manufacturers to specialize in what they are good at; and likewise for lens designers and their own production facilities. The former is electronics while the latter is about optics.

By defining standards for lens mounts, we all benefit from market competition, which drives quality, feature, and price differentiation.

Some mounts are for large-format sensors. Some for small sensors. Some for “quick change”. Some for stability. Some can fit several niches. Some can in theory but shouldn’t be pushed in practice. Below we provide examples.

Lens families from a single manufacturer by sensor size and pixel size – Courtesy Schneider Optics

What should we consider with F-mounts?

If you are a sports photographer, F-mount may be an excellent choice. The bayonet mount design is ideal for quick lens changes, and the “money shot” may require a quick lens swap. If shooting at really short exposure times, inherent instability in the mount design may not have an impact on image quality.

While the F-mount name traces to the famous Nikon F camera series, one might also think of it as for “Fotographie” – the German work for photography – if you like mnemonic hints.

But for machine vision applications, one typically mates the lens to the camera “forever”, so quick-change benefits are of little value. And compared to screw mounts, for example, it’s clear that the bayonet mount, with just two securing points, might suffer in a high-vibration environment. Whether on the factory floor, a traffic camera gantry, or a moving vehicle, the lens and camera should act as one. Stability is key.

For the record, F-mount defines a standard Flange Distance of 46.5mm from the mounting surface of the camera to the sensor, as well as standardized mechanics on the size and position of the male pins on the lens and the female receptors on the camera body. For those cameras or lenses with electrical contacts as well, there are variances. But mechanically and optically and F-mount is an F-mount.

What about the M42 lens mount?

While the M42 lens mount came into existence for “photography”, when computers and then machine vision emerged, M42 has become one of many popular lens mounts. The threaded screw mount design provides a very secure connection that binds along several turns of the screw – so it’s very resistant to vibration.

But while the conceptual design is great, M42 isn’t really a “full standard” in two important ways…

M42 doesn’t define flange distance

Every lens must precisely focus light rays onto the sensor surface. Camera makers position sensors a precise distance from the shoulder of the mount, a distance referred to as the flange distance, or flange focal distance. Curiously, there isn’t universal agreement on what that distance should be – though there is some convergence on a couple of de facto conventions.

The M42 lenses may need to have an extension tube added so that they can image on a camera sensor. Thankfully an extension tube is an inexpensive but effective accessory – but it’s important to note focal distances and source components accordingly.

M42 doesn’t define thread pitch

The second caveat with M42 mounts is that there are at least two common thread pitches offered: both 0.75 and 1.0.

Annotated snapshot of 1stVision lens selector tool.

If we use the 1stVision lens-selector, the Lens Mount dropdown shows both M42x0.75 as well as M42x1 options (as well as many other lens mounts). So if you know the camera mount specifications, you can find lenses that will thread correctly – but one needs to pay attention!

All the mounts we offer

To the left is a snapshot from the 1stVision lens-selector, showing the dropdown for all lens mounts we offer. If one chooses “All” it yields some 200 lenses across more than 10 manufacturers.

By specifying the lens mount, for the camera you are considering, one need only select a couple of additional dropdowns like sensor format, and focal length, to home in on candidate lenses for your application.

Each mount has its role. While a camera designer sometimes has options relative to sensor size, intended market, and price : performance decisions, there are good reasons why each mount type exists. And while some cameras are available with two or more mount options, generally speaking the camera you choose will dictate the mount – and hence the lens options.

Don’t fixate on the mount

While we’ve discussed certain aspect of lens mounts in this blog, you can generally trust that camera designers have chosen a suitable one for any particular camera – after all they want to maximize the number of cameras they can sell. There are many other considerations in machine vision lens selection. You can read all about it, or just…

February 13, 2025February 13, 2025

Moritex ML-M-HR 2/3″ Format Lenses

Superior vibration resistance and mechanical design

Two of six available ML-M-HR lens models – Courtesy Moritex

Value Engineering

Every field with diverse product offerings has its own broad mix from which to choose. Some offerings are generalized; some fit a specific niche. When designing a machine vision application, and choosing components like cameras, sensors, lenses, lighting, etc., each component has to be at least slightly better than “good enough”, but need not be more than needed. The whole field of value engineering has evolved to guide practitioners in achieving required functionality while also respecting budgetary goals.

Larger FA series design goals which ML-M-HR series share- Courtesy Moritex

Moritex ML-M-HR lens series

The Moritex ML-M-HR series is part of Moritex larger FA Series of lenses. The “FA” stands for Factory Automation, which suggests points including:

Robust mechanical engineering
Quality designed to deliver reliable results and stand the test of time
Priced to permit volume purchases by achieving return on investment

Of course, the lenses are not constrained to factory automation, and you may purchase as few as you need. The factory automation insight just helps to understand their design heritage and largest market.

Specifics:

Key attributes of the Moritex ML-M-HR lens series

Pixel size and resolving capacity

Designed for 4.5 µm pixels, the lenses may of course also be used with larger pixels, but aren’t suitable for smaller. So they are an ideal fit for Sony Pregius 3rd generation sensors.

See Moritex lens families for other pixel sizes and lens types. The Moritex ML-M-HR lenses resolve to 130 line pairs / mm. See our Knowledge Base article Key Considerations in Machine Vision Lens Selection for generalized guidance on concepts.

With wide-range anti-reflective (AR) coatings, the lenses provide consistent transmission from visible (Vis) through near infrared (NIR) wavelengths, i.e. 400 ~ 1100nm.

Six member family

There are six choices in the Moritex ML-M-HR series, spanning from focal lengths 8mm – 50mm, at typical intervals. The link in the previous sentence takes you to the detailed table – and quote request buttons.