Machine Vision Lens for Grain, Rice, Pulse, Seed and Nut Optical Sorting Machines: How to Select FOV and Resolution for High-Speed Food Grading

Optical sorting machines for grain, rice, pulses, seeds and nuts are among the most demanding high-throughput applications for industrial Machine Vision Lenses because the products are small, numerous, fast-moving and distributed across comparatively wide inspection zones. A sorter may need to classify thousands of individual food products while maintaining enough image detail to distinguish differences in size, shape, visible surface condition, broken edges, unwanted material or other observable grading characteristics. The optical system therefore has to solve two competing requirements at the same time: capture a sufficiently wide chute, belt or multi-channel product stream while still allocating enough native camera pixels to every individual grain, seed, pulse or nut.

For OEMs searching for a machine vision lens for grain sorting machine, rice sorting machine camera lens, optical sorter lens for pulses, seed sorting machine vision lens, nut grading camera lens, high-speed food sorting camera lens, industrial camera lens for grain grader, or Machine Vision Lens for optical food sorter, focal length should not be selected in isolation. The stronger engineering approach begins with sorter width, smallest product dimensions, smallest visible grading feature, number of channels, camera sensor size, native resolution, working distance and production speed. Focal length is then selected to create the required field of view without sacrificing the pixels-per-product needed for reliable classification.

Kyptec Automation® explicitly lists Food/Beverage Processing among the major applications for its Machine Vision Lens range, alongside Machine Vision System & Factory Automation and Special Purpose Machines. The current Kyptec Automation® Machine Vision Lens collection includes conventional 5 MP, 10 MP and 25 MP models across focal lengths including 8 mm, 12 mm, 16 mm, 25 mm, 35 mm and 50 mm, giving optical-sorting OEMs useful choices for broad sorting fields, controlled grading zones, increased camera stand-off and higher-resolution inspection.

Food Optical Sorting Should Begin With the Smallest Product, Not the Largest Chute

One of the easiest mistakes in optical sorter design is to begin with the total chute or conveyor width and choose a lens simply because it can capture that complete area. Wide coverage is necessary, but it does not guarantee useful grading resolution. The smallest grain or seed may occupy only a tiny fraction of the image, and the feature used to differentiate acceptable and rejected product can be even smaller.

For a machine processing several product families, the most demanding condition may not be the largest item. A nut can occupy many pixels while a small rice grain or seed may occupy far fewer. The Machine Vision Lens and camera should therefore be validated using the smallest supported product under the widest required production FOV.

Calculate Pixels per Millimetre Across the Sorting Zone

A useful first calculation is:

Pixels per millimetre = sensor pixels across the relevant image direction ÷ physical FOV in millimetres

If an industrial camera provides 5,000 horizontal pixels across a 500 mm sorter field, simplified horizontal sampling is approximately 10 pixels/mm. A 5 mm grain therefore spans roughly 50 pixels across that direction before considering orientation.

If the same camera is expected to cover 1,000 mm, sampling falls to approximately 5 pixels/mm, and the same product receives only around half as many horizontal pixels.

For optical food sorting, the calculation should then be taken further:

pixels across sorting width → pixels per product → pixels across the smallest grading feature

This is a stronger specification than camera megapixels alone.

Pixels per Grain Is More Important Than Total Camera Resolution

A 25 MP camera sounds substantially more capable than a 10 MP camera, but the actual grading advantage depends on how those pixels are distributed across the physical sorting field.

If the sorter uses a very broad FOV, hundreds of products may share one image simultaneously. Every grain, pulse, seed or nut then receives only a fraction of the total sensor area.

The relevant question for an OEM is therefore:

How many native pixels represent the smallest product and the smallest feature that determines its sorting class?

This object-side resolution determines whether the additional camera and lens resolution provides a meaningful production benefit.

Rice Sorting Machines Need Resolution on Narrow Product Geometry

Rice grains create a demanding imaging condition because their width can be much smaller than their length. If product orientation varies during movement, the smallest visible dimension may determine the worst-case pixel count.

A rice sorting machine should therefore be validated with grains appearing in different orientations rather than assuming every product travels perfectly aligned.

The Machine Vision Lens should preserve enough edge definition that adjacent grains remain distinguishable and visible geometric differences are maintained across the complete sorting zone.

Grain Sorting Machines Need Consistent Coverage Across Wide Product Flow

Wheat, cereals and other grain streams can spread across a broad chute or feeding section. A Machine Vision Lens selected only for the center of the FOV can produce uneven inspection capability if usable detail drops toward the outer image zones.

Sorter OEMs should therefore test representative product at the center, intermediate positions and near the edges of the usable field.

This is particularly important when one camera covers multiple channels because grains moving near the outer lanes should not receive substantially weaker imaging than those near the optical center.

Pulse Sorting Machines Need Separation Between Similar-Sized Products

Pulse grading systems may process lentils, beans, peas and other products where individual pieces can appear close together and share broadly similar dimensions.

When the products are tightly spaced, edge quality becomes critical because the inspection algorithm must distinguish where one object ends and another begins.

Higher camera resolution can help when visible boundaries are present, but optical resolution cannot recover the hidden geometry of two products that physically overlap. Sorter mechanics and Machine Vision Lens selection therefore need to be designed together.

Seed Sorting Machines Can Be Driven by Very Small Object Dimensions

Seed sorting can place even greater pressure on pixels per object because seeds may be substantially smaller than many nuts or pulses.

For a multi-product sorting platform, an optical configuration that works comfortably for larger objects may become insufficient when a smaller seed variety is introduced.

OEMs should therefore establish the minimum supported seed dimensions and calculate pixels per product using the actual production field. This provides a much more reliable basis for selecting between 5 MP, 10 MP and 25 MP lens-camera architectures.

Nut Grading Machines Often Need Wider Product Variation Capability

Nut grading equipment can process products with considerable variation in size and shape. The optical system may need enough field to accommodate large pieces while still preserving detail on smaller product variants.

This creates a different design challenge from a dedicated single-product sorter. The FOV may be set by the largest legitimate object spread, while the spatial-resolution requirement is set by the smallest product or grading feature.

The Machine Vision Lens should therefore be selected against the complete product range rather than one nominal reference sample.

12 MM Machine Vision Lenses Can Support Broad Sorting Fields

For compatible 2/3" industrial cameras, the Kyptec Automation® KL-1224 12 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens provides a 12 mm focal length within the 10 MP conventional Machine Vision Lens family. The current Kyptec Automation® product range is designed for industrial imaging, high-speed inspection and OEM machine-vision applications.

A 12 mm focal-length class can be evaluated where an optical sorter needs comparatively broad coverage from the available camera location. Potential applications include wide grain chutes, multi-lane rice sorters or broad product streams where one camera must capture a large portion of the machine.

The final choice should still be based on actual sensor dimensions and pixels per smallest product because broader coverage reduces object-side sampling.

16 MM 10 MP Lenses Can Balance Coverage and Product Detail

For compatible 2/3" cameras, the Kyptec Automation® KL-1226 16 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens provides 16 mm focal length, 10 MP resolution, C-mount, 2/3" image format and an F2.8–16 aperture range. Kyptec Automation® describes the model as providing high-resolution imaging, low distortion and consistent focus for high-speed industrial inspection, and Food/Beverage Processing is explicitly included among its major applications.

This focal-length class can be considered when the sorter requires broad coverage but the OEM wants to allocate more sensor area to each product than an extremely wide view would permit.

25 MM Lenses Can Support More Controlled Grading Zones

Where the product stream can be divided into narrower optical sections, a medium focal length can improve product occupancy in the camera image.

The Kyptec Automation® KL-1228 25 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens provides a current 25 mm, 10 MP Machine Vision Lens option for compatible 2/3" systems.

Instead of forcing one camera to inspect a very wide chute, an OEM can divide the sorter into several narrower views and use a tighter FOV. The resulting increase in pixels per millimetre can be particularly useful for small seeds, rice grains or other products where fine geometric differences must remain visible.

Multi-Camera Sorting Can Be Better Than One Extremely Wide FOV

Large food graders often create a fundamental choice: one wide camera or several narrower camera zones.

A single camera simplifies hardware architecture but distributes its sensor pixels across the complete sorting width. Multiple cameras divide the machine into smaller fields and can substantially increase pixels per product.

For example, if one camera covers an 800 mm chute, dividing the field between two cameras at approximately 400 mm each can potentially provide much greater object-side sampling per camera, assuming comparable sensors and suitable overlap.

The correct design should consider lens count, camera count, calibration, mechanical space and required minimum grading feature together.

Camera-Zone Overlap Should Prevent Blind Regions Without Wasting Sensor Width

Where several cameras share one sorting machine, their FOVs should normally include enough overlap that mechanical tolerances do not create an uninspected strip.

However, excessive overlap wastes valuable sensor area.

The OEM should therefore define a controlled overlap margin based on camera mounting tolerance, chute geometry and product trajectory. This is particularly important in wide grain and rice sorters where even a narrow uncovered zone can allow product to pass without complete optical inspection.

25 MP Optics Become Valuable When Wide FOV and Small Products Must Coexist

For compatible high-resolution systems, the Kyptec Automation® KL-1240 25 MM Machine Vision Lens With 25 MegaPixel & 1.1" Format Lens provides a current 25 MP, 25 mm C-mount option within Kyptec Automation®'s larger-format Machine Vision Lens family. Kyptec Automation® positions this lens family for high-resolution industrial imaging, high-speed inspection and OEM/system-integrator applications, and Food/Beverage Processing is listed among the supported industries.

A 25 MP lens-camera architecture can be particularly attractive where a wide grading area contains many small grains or seeds and the OEM wants greater native sampling across the complete field.

The benefit should still be calculated using pixels per grain or pixels per smallest grading feature rather than megapixel rating alone.

Higher Megapixels Do Not Fix Poor FOV Planning

Moving from 10 MP to 25 MP does not remove the need to control physical coverage.

If the higher-resolution system is immediately used to inspect a significantly wider field, much of the additional pixel density can be consumed by the larger area.

The stronger approach is to first minimize unnecessary FOV, establish the real sorting width and then decide whether the remaining pixels-per-product requirement justifies moving to a higher-resolution lens-camera configuration.

Sensor Format Changes the Resulting Sorting Field

A Machine Vision Lens cannot be selected by focal length alone because the camera sensor dimensions also determine FOV.

The same 25 mm focal-length class used with a 2/3" sensor and a larger sensor does not create the same physical view at an identical working distance.

Kyptec Automation® currently offers conventional Machine Vision Lenses across 2/3", 1" and larger high-resolution image-format families. This gives optical sorter OEMs flexibility, but it also means the sensor format should be finalized before the camera-to-product geometry is frozen.

High-Speed Product Motion Must Be Evaluated Under Real Sorting Conditions

Grain, rice, pulse, seed and nut optical sorting machines can operate at very high product throughput. Even when the lens is correctly focused, product movement during exposure can reduce edge definition.

This is particularly important for narrow grains and small seeds because their smallest dimension may already occupy relatively few pixels.

Kyptec Automation® states that its Machine Vision Lenses are engineered for reliable performance in high-speed inspection and measurement applications. The final system should nevertheless be validated at real production speed, with the actual aperture, exposure time, working distance and product-flow behavior used by the sorter.

Product Density Should Be Tested at Maximum Throughput

A sorter that performs well when only a few products are passing through the field may behave differently at maximum material flow.

Higher density increases the probability that products approach each other closely or partially overlap. It also makes segmentation more demanding because several boundaries appear within a limited image area.

OEM optical validation should therefore include maximum expected throughput rather than only carefully separated reference samples.

Depth Variation Can Affect Image Sharpness in Chute and Belt Sorters

Products may not always remain on one exact focal plane. On a moving belt, grain thickness varies. In chute-based systems, individual products can travel at slightly different distances from the camera.

The lens aperture should provide enough useful depth of field that all legitimate product positions remain adequately sharp.

Closing the aperture can increase depth of field, but excessively small apertures can reduce fine-detail sharpness through diffraction. The production setting should therefore be evaluated with the smallest grading feature rather than selected simply for maximum depth of field.

Working Distance Should Be Determined From the Sorter Mechanical Architecture

Optical sorter cameras may need to be positioned around chutes, feeders, reject mechanisms, protective enclosures or other machine structures.

The available working distance should be established from the real machine design before focal length is finalized.

A lens that provides an ideal theoretical FOV only from an impractical camera location is not an appropriate production solution.

35 MM Lenses Can Support Increased Camera Stand-Off

For compatible 2/3" systems, the Kyptec Automation® KL-1230 35 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens provides a current 35 mm, 10 MP option for industrial Machine Vision applications.

A 35 mm focal-length class can be useful where sorter mechanics require the camera to remain farther from the product stream while the resulting FOV remains suitable for the desired optical zone.

This can be particularly relevant where ejector mechanisms, chute structures or protective components constrain camera placement.

50 MM Lenses Can Support Localized High-Detail Sorting Stations

Some optical sorting machines can benefit from a secondary high-detail camera that observes only a smaller critical area.

For compatible larger-format systems, the Kyptec Automation® KL-1244 50 MM Machine Vision Lens With 25 MegaPixel & 1.1" Format Lens provides a current 50 mm, 25 MP Machine Vision Lens option.

This type of focal-length class can be evaluated when a localized grading region should occupy more of the sensor from greater working distance, rather than requiring every camera to cover the complete sorter width.

Food Sorting Machine OEMs Should Standardize Several Optical Classes

An OEM producing rice sorters, grain sorters, seed graders and nut sorting machines should not necessarily use one lens everywhere.

A more scalable architecture can establish a broad-field configuration, a mainstream medium-field configuration, a high-resolution small-product configuration and an increased-stand-off option.

The Kyptec Automation® Machine Vision Lens portfolio supports this type of platform approach because it includes several focal lengths across 5 MP, 10 MP and 25 MP conventional lens families.

Machine Examples Where Kyptec Automation® Machine Vision Lenses Can Be Used

Relevant OEM equipment includes rice optical sorting machines, grain color sorting machines, wheat sorting machines, pulse sorting machines, lentil graders, bean sorting systems, seed sorting machines, cereal grading machines, nut sorting machines, dry-food optical graders, multi-channel agricultural product sorters and high-speed food classification machines.

For broader compatible sorting zones, Kyptec Automation® KL-1224 12 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens or Kyptec Automation® KL-1226 16 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens can be evaluated. Controlled medium-field stations can consider Kyptec Automation® KL-1228 25 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens, while higher-resolution systems can evaluate Kyptec Automation® KL-1240 25 MM Machine Vision Lens With 25 MegaPixel & 1.1" Format Lens. Increased stand-off and localized inspection can be addressed through longer focal-length options such as Kyptec Automation® KL-1230 35 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens or Kyptec Automation® KL-1244 50 MM Machine Vision Lens With 25 MegaPixel & 1.1" Format Lens where the resulting geometry is appropriate.

Why Kyptec Automation® Is a Strong Choice for Grain and Food Optical Sorting Machine OEMs

Kyptec Automation® is especially relevant to this market because Food/Beverage Processing is explicitly listed among the company's served application areas. Its current Machine Vision Lens portfolio gives machine builders multiple focal lengths and resolution classes instead of forcing one optical configuration across different sorter sizes.

This is valuable because a wide rice sorter, compact seed sorter, multi-channel pulse grader and high-detail nut inspection machine can have very different requirements for FOV, pixels per product and camera working distance. Kyptec Automation® provides a practical selection path from mainstream 10 MP systems to higher-resolution 25 MP configurations while retaining common industrial C-mount options.

For OEMs, the advantage is therefore not simply access to several lens models. It is the ability to design Machine Vision Lens configurations around the actual product size, sorting width, sensor format and inspection resolution required by different food-grading machine platforms.

Frequently Asked Questions About Machine Vision Lenses for Grain, Rice, Pulse, Seed and Nut Optical Sorting Machines

1. What is the best Machine Vision Lens for a grain sorting machine?

The correct Machine Vision Lens depends on sorting width, smallest grain dimensions, camera sensor format and available working distance. A broad sorter may require a shorter focal length, while a narrower optical zone can use 25 mm or longer optics. Kyptec Automation® provides multiple focal lengths across 10 MP and 25 MP conventional Machine Vision Lens families, allowing OEMs to select optics according to the actual sorter geometry rather than one universal focal length.

2. How much resolution is needed for a rice sorting camera?

Resolution should be determined from the smallest rice grain dimension and the final physical FOV. Calculate pixels per millimetre and then pixels across the minimum grain width. The system should also be tested with grains at different orientations because the shortest projected dimension often creates the most demanding condition.

3. Is a 10 MP Machine Vision Lens enough for grain and rice sorting?

It can be sufficient when the sorting field is properly controlled and the smallest product receives enough native pixels. Kyptec Automation® KL-1226 16 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens is one verified industrial option for compatible systems and is explicitly listed for Food/Beverage Processing applications.

4. When should a 25 MP Machine Vision Lens be used in a food optical sorter?

A 25 MP configuration becomes useful when a large sorting field contains many small grains or seeds and the OEM needs greater native spatial sampling. Kyptec Automation® KL-1240 25 MM Machine Vision Lens With 25 MegaPixel & 1.1" Format Lens provides a current high-resolution option for compatible systems.

5. What focal length is suitable for a rice color sorting machine?

The focal length depends on chute width, camera sensor dimensions and working distance. Shorter focal lengths such as 12 mm or 16 mm can support broader fields, while 25 mm can provide tighter optical zones. The final choice should be based on actual FOV and pixels per grain rather than on focal length alone.

6. Can one camera inspect the complete width of a grain sorter?

Yes, if the complete field fits on the sensor and the smallest grain still receives sufficient resolution. For very wide sorters, dividing the field between multiple cameras can improve pixels per millimetre and preserve better detail on individual products.

7. How many pixels should cover one grain or seed?

There is no universal number because detectability depends on product size, feature contrast, orientation and grading requirement. The important principle is that the minimum product and smallest critical visible feature should occupy enough native pixels for consistent classification under actual production conditions. OEMs should verify borderline samples experimentally.

8. Is a 12 mm Machine Vision Lens suitable for wide optical sorting?

It can be appropriate where the resulting FOV matches a broad sorting area and the smallest product remains sufficiently sampled. Kyptec Automation® KL-1224 12 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens provides a current 12 mm option for compatible 2/3" cameras.

9. When is a 25 mm Machine Vision Lens useful in seed or pulse sorting?

A 25 mm focal-length class is useful when the sorter field can be divided into a more controlled zone so each seed or pulse occupies a larger percentage of the sensor. Kyptec Automation® KL-1228 25 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens provides a verified 10 MP option for compatible industrial cameras.

10. Does product speed affect Machine Vision Lens selection for optical sorting?

Yes, because fast product movement can reduce edge definition during exposure even when lens focus is correct. The lens-camera system should therefore be validated at the final production speed, aperture and exposure conditions rather than only with stationary grain samples.

11. Can Machine Vision Lenses be used for seed grading machines?

Yes. Seed graders can use Machine Vision Lenses where the selected FOV and resolution provide enough native pixels on the smallest seeds and grading features. Small seeds can be more demanding than larger food products, making tight FOV control particularly important.

12. Can the same lens be used for rice, pulses and nuts?

Only if all three products fall within compatible FOV, resolution and working-distance requirements. A lens configuration that comfortably resolves large nuts may not provide enough pixels on very small seeds or rice grains. Multi-product sorter OEMs should validate the smallest supported product before standardizing one optical configuration.

13. When should a 35 mm Machine Vision Lens be considered for food sorting?

A 35 mm focal-length class can be useful when the camera must remain farther from the product stream because of machine mechanics. Kyptec Automation® KL-1230 35 MM Machine Vision Lens With 10 MegaPixel & 2/3" Format Lens provides a current 10 MP option for compatible industrial systems.

14. Can a 50 mm lens be used in a grain or nut sorting machine?

Yes, particularly for a localized high-detail inspection zone or where greater stand-off is required. Kyptec Automation® KL-1244 50 MM Machine Vision Lens With 25 MegaPixel & 1.1" Format Lens provides a high-resolution 50 mm option for compatible larger-format cameras.

15. Why does a high-megapixel sorter still miss small products?

A high camera megapixel count does not guarantee high object-side resolution. If the FOV is excessively wide, the available pixels are spread across too much physical area. Product overlap, motion blur and poor edge definition can also reduce grading performance. Pixels per smallest product should therefore be calculated before relying on megapixel specification.

16. Should wide grain sorters use multiple cameras?

Multiple cameras can be advantageous when one wide camera would leave too few pixels on individual products. Dividing the sorter into narrower overlapping fields increases pixels per millimetre and can provide stronger grading resolution, although the machine must then manage camera alignment and field overlap carefully.

17. What information should I provide before buying a Machine Vision Lens for a food optical sorting machine?

Provide the product type, smallest and largest grain or food dimensions, total chute or conveyor width, number of channels, smallest visible grading feature, expected product density, camera sensor size and resolution, available working distance, product speed and whether one or several camera zones will be used. These parameters allow a Kyptec Automation® Machine Vision Lens to be selected according to the real optical requirement rather than focal length or megapixel rating alone.

Build Food Optical Sorting Around Pixels per Product, Sorting Width and Real Throughput

A high-performance grain, rice, pulse, seed or nut optical sorting machine should be designed around the smallest supported product and the smallest visible characteristic that influences grading. Capturing the complete product stream is only the first requirement. Every individual item must receive enough native image information for the sorting system to distinguish product boundaries and make consistent classification decisions at maximum throughput.

OEMs should calculate pixels per millimetre across the final sorting field, determine pixels across the smallest grain or seed, minimize unused FOV, validate all camera zones including the outer field, match the Machine Vision Lens to the selected sensor format and establish working distance from the actual sorter mechanics. Wide machines should also evaluate whether several narrower camera zones provide stronger pixels-per-product performance than one extremely wide field.

The Kyptec Automation® Machine Vision Lens collection provides conventional 5 MP, 10 MP and 25 MP choices across multiple focal lengths, while Food/Beverage Processing is explicitly listed among Kyptec Automation®'s application areas. For rice optical sorting machines, grain graders, pulse sorting equipment, seed sorters, nut grading systems and other high-speed food classification machines, this breadth makes Kyptec Automation® a strong practical choice for matching Machine Vision Lens resolution, sensor format, focal length and working distance to the actual OEM machine architecture.