Fixed vs Varifocal vs Zoom Machine Vision Lenses: Focus Behavior, Tradeoffs, and Selection
Three lens types differ on one operational question: what happens to focus when the focal length changes? This guide covers the definitions, the tradeoffs, the prototype-to-production workflow, and catalog-verified options.
A fixed focal length lens has one effective focal length and typically gives the best sharpness, distortion control, and calibration stability per dollar. Choose it once working distance and field of view are confirmed. A varifocal lens changes focal length but loses focus with every adjustment, so it must be refocused after zooming. A parfocal lens, the true zoom, holds focus through the focal change.
Adjustable lenses earn their cost during prototyping and in systems that genuinely reframe during operation. Everywhere else, fixed focal is the production answer.
What is the difference between fixed, varifocal, and zoom lenses?
A fixed focal length lens has one effective focal length set at manufacture. A varifocal lens changes focal length but loses focus with every adjustment. A zoom lens (properly, a parfocal zoom) changes focal length while holding focus. Fixed focal designs typically give the best sharpness, distortion control, and calibration stability per dollar.
The three types answer different operational needs. The deciding question is not image quality; it is when, and how often, the focal length has to change. The table below is the reference for every decision on this page.
| Property | Fixed focal | Varifocal | Parfocal zoom |
|---|---|---|---|
| Focal length | One EFL, set at manufacture | Adjustable range | Adjustable range |
| Focus through a focal change | Not applicable; focus is set once | Lost; refocus after every change | Held through the range |
| Mid-cycle reframing | Nein | No; requires a stop and refocus | Yes, manual or motorized |
| Optical complexity | Lowest | Moderate, with one moving group | Highest, with coordinated moving groups |
| Relative cost | Lowest | Low to moderate | Höchster |
| MTF at a given focal length | Optimized at one operating point | Balanced across the range | Balanced across the range |
| Verzerrung | One profile; calibrate once | Changes with focal setting | Changes with zoom position |
| Calibration burden | Single calibration typically holds | Recalibrate after each adjustment | Calibrate per zoom position used |
| Package size and weight | Smallest (a 12.5mm M12 lens is 7g) | Larger | Largest |
| Best fit | Stable production geometry | Commissioning, then locked | Framing that changes during operation |
The pattern across the industrial market follows the last row. Fixed focal designs make up the bulk of machine vision lens catalogs, varifocal designs cluster in surveillance-adjacent formats, and true parfocal zooms are the smallest group because the compensating mechanics cost the most to build well. Availability alone pushes production systems toward fixed focal.
Many lenses sold as "zoom" in CCTV, consumer, and industrial catalogs are varifocal designs. The bench test takes one minute: set focus at the working distance, change the focal length, and watch sharpness. If the image goes soft, the lens is varifocal regardless of its label. Assume varifocal behavior unless the datasheet explicitly states focus is maintained through the range.
What is a fixed focal length lens?
A fixed focal length lens has one effective focal length (EFL). There is no zoom ring; for a given sensor the lens produces one angle of view. It is the machine vision default because the optical design is corrected at a single operating point instead of compromised across a range, and because one calibration typically holds until the lens is disturbed or the environment shifts.
The focal length you need is a calculation, not a preference. Three measured inputs (working distance, active sensor width, and required scene width) fix the answer:
A sensor with a 7.2mm active width imaging a 144mm-wide scene from 500mm needs (7.2 × 500) / 144 = 25mm. The focal length selection guide walks the full sequence, and the EFL calculator runs the same geometry in seconds. Once the number is verified on a real target, buying flexibility you will never use has no return.
Fixed focal does not mean fixed focus
Fixed focal refers to the focal length. Focus is a separate mechanical adjustment that sets the distance of best sharpness, and most fixed focal industrial lenses keep it: the engineer focuses at the working distance during installation, confirms sharpness at the target plane, and locks the ring. Some compact M12 lenses ship pre-focused from the factory; those are fixed focus lenses, a different property covered in the autofocus guide. Aperture is also independent of focal length: many fixed focal C-mount lenses carry an adjustable iris, while M12 lenses typically have a fixed aperture.
Photography calls this a prime lens. The optics are the same concept; the specification language differs. Industrial fixed focal lenses document sensor format coverage, distortion, resolution rating, and minimum working distance, the parameters a vision system is calibrated against. Beyond focal length, verify image circle against the sensor diagonal, corner MTF at the operating aperture, and distortion against the measurement tolerance before ordering.
Aperture is a separate axis from focal length
A fixed focal length says nothing about how much light the lens passes or how much depth of field it produces at a given working distance. That is a function of the iris, and the iris is an independent design choice from the focal length. Many fixed focal C-mount lenses carry an adjustable iris ring, typically spanning something like F/2.0 to F/16, so the same lens can be stopped down for more depth of field or opened up for more light with no change to field of view or focal length. M12 lenses typically ship with a fixed aperture set at manufacture, which keeps the barrel small but removes that adjustment from the field.
Stopping down an adjustable iris increases depth of field and reduces the visible blur from any residual focus mismatch across the field. It does not "compress" or eliminate field curvature or astigmatism, which are properties of the optical design, not the aperture setting (Smith, Modern Optical Engineering, 4th ed.). In machine vision, stopping down a C-mount lens is often a practical option specifically because illumination is programmatically controlled: a smaller aperture costs stops of light, and a vision system can recover that loss with brighter LEDs or longer exposure without touching the mechanical setup on the line. That tradeoff between iris and illumination is covered in more depth in the f-number guide and the depth of field guide.
"Fixed focal" and "fixed aperture" are two different specifications that happen to share a word. A fixed focal C-mount lens with an iris ring is fixed in angle of view but adjustable in light throughput and depth of field. Read both specs independently before assuming a fixed focal lens has no field-adjustable controls at all.
What is a varifocal lens?
A varifocal lens adjusts focal length by moving an internal element group, and the plane of focus shifts with it. The zoom ring and focus ring are decoupled: after any focal-length change the image is soft until the focus ring is readjusted. Varifocal designs defer the focal-length decision from the purchase order to the installation.
That deferral is the entire value proposition. Mount the camera, turn the zoom ring until the framing is right, restore sharpness with the focus ring, lock both. From that point the lens behaves like a fixed focal lens: the same working distance, the same field of view, run after run. Engineers reach for varifocal lenses during proof-of-concept work at untested mounting positions, acceptance testing where the installed geometry differs from the drawing, and multi-product stations where framing changes between production runs.
The optical cost is real. A designer correcting one focal length can target aberrations at that exact configuration; a varifocal designer balances correction across the whole range. A varifocal set to 8mm will typically show softer corners and more distortion than a fixed 8mm lens from the same price tier.
What a varifocal lens does not solve
It does not solve an unstable working distance. If the target moves toward or away from the camera during operation, the fix is sufficient depth of field to cover the travel, not a lens that requires a technician to readjust it. Varifocal adjustments are commissioning steps, not runtime corrections.
It also does not preserve calibration. Changing the focal setting changes image scale, the distortion profile, and the principal point, so distortion coefficients and pixel-per-mm factors captured at one setting are invalid at another. Stereo and structured-light systems are the strictest case: fix the focal length before calibrating and treat the zoom ring as sealed from that point forward.
What is a zoom machine vision lens?
A zoom machine vision lens changes focal length while a compensating optical group holds the image plane in place, so the picture stays sharp through the range. That focus stability is what separates a true zoom from a varifocal, and it is why zoom lenses carry more elements, tighter mechanical tolerances, and higher prices.
Inside the barrel, at least one group travels to change focal length while a second group moves in coordination to cancel the focus shift. A manual design couples the two through a machined cam track; a motorized design drives them with one or two motors (Kingslake, Lens Design Fundamentals, 2nd ed., §18.3; Smith, Modern Optical Engineering, 4th ed.). More moving surfaces mean more tolerance stack-up, which is where zoom lenses give back some of their flexibility as MTF variation across the range.
Zoom ratio is the longest focal length divided by the shortest: 6mm to 42mm is 7X. The ratio describes reach, not quality, and wider ratios force larger design compromises at the extremes. For most machine vision reframing tasks a 2X to 4X range is enough; buy the range your application actually spans.
Effective aperture is the spec that surprises integrators. On many zoom designs the entrance pupil diameter stays roughly constant while focal length climbs, so the f-number climbs with it:
Any acquisition loop that commands a zoom move must also command an exposure, gain, or illumination change. Datasheets that quote a single f-number for a zoom lens are almost always quoting the wide end.
Manual vs motorized zoom control
A manual zoom lens is set by hand at commissioning and left alone: the cam track holds the focal length and focus relationship mechanically, with no electronics involved. A motorized zoom adds one or two motors driving the same cam geometry under software or remote command, which is what makes runtime reframing possible without a technician at the lens. The optical compensation between zoom and focus groups is identical in both cases; motorization only changes who or what turns the ring.
Motorization adds failure modes a manual zoom does not have: motor step accuracy, encoder or open-loop position tracking, and settling time after a move before the image is usable for measurement. A vision system that commands zoom moves during a cycle needs to know the move has actually completed and settled (not just that the command was sent) before it trusts the next frame for measurement. Cheaper motorized zooms sometimes drive both groups open-loop with no position feedback, which pushes the repeatability question in the section below to the front of the evaluation rather than the back.
What is a parfocal lens?
A parfocal lens maintains focus while its focal length changes. The word names the focus behavior, nothing else. It is not a synonym for any lens with a zoom ring. A true zoom is parfocal by design; a varifocal is not, because it has no compensating group.
The term is applied inconsistently across the industry. In cinema optics, parfocal is a precise, tested property. In surveillance catalogs, "varifocal" often labels any adjustable lens, including a few that hold focus reasonably well. In industrial listings, "zoom" and "varifocal" appear interchangeably. The consequence for machine vision engineers is simple: confirm focus behavior from the first-party datasheet or at the bench before designing an automated reframing step around a lens. That applies to our own catalog: the CIL461 7X zoom M12 lens is a manual varifocal zoom that does not hold focus through a focal change, so set the focal length, restore focus, and lock both rings, then confirm sharpness across the range at the bench before treating it as a fixed-focus reframing lens.
Varifocal vs zoom lenses in machine vision
Both types change focal length; only the parfocal zoom does it without losing focus. Operationally that one difference decides everything. A varifocal reframe means stopping the line: adjust the zoom ring, restore focus, recalibrate, resume. A parfocal zoom reframes mid-cycle, manually or by motor command, with focus intact, though pixel-to-world calibration still only applies at the zoom position where it was captured.
If the focal length is set once at commissioning and locked, the distinction is moot and the cheaper varifocal wins. If framing must change during operation without a refocus step (sequential part sizes at one station, or software-controlled framing on a camera nobody can physically reach), the parfocal zoom is the only adjustable type that works. Price the decision accordingly: pay for parfocal behavior when the application uses it, not as insurance.
How do you choose between fixed, varifocal, and zoom lenses?
Choose by when the focal length changes. If the geometry is confirmed and stable, use a fixed focal lens. If the focal length is set once at commissioning and then locked, a varifocal works. If the focal length changes repeatedly during operation without a refocus step, only a parfocal zoom fits. Moving from an adjustable prototype lens to a fixed focal production lens should be an explicit design review item, not an accident.
| Your situation | Lens type |
|---|---|
| Working distance and field of view confirmed; geometry frozen | Fixed focal length lens |
| Framing uncertain until installation; adjusted once, then locked | Varifocal |
| Field of view changes during operation; no refocus step allowed | Parfocal zoom, motorized if commanded by software |
| Target distance itself varies during operation | Fixed focal with sufficient depth of field, not a zoom |
| High-accuracy measurement with tight distortion tolerance | Fixed focal, calibrated once at installation |
The most common workflow uses an adjustable lens as an instrument that answers one question (what focal length does this application actually need) and then retires it:
- Prototype with a zoomSweep the focal range at the real mounting position until the field of view and working distance are right. One 6mm–42mm zoom replaces a drawer of fixed candidates.
- Record the winning settingRead the focal length off the barrel markings, or measure it empirically from image scale at a known working distance.
- Verify the numberCheck the candidate focal length against your sensor and scene in the field of view calculator before committing a purchase order.
- Source the fixed focal lensBuy the nearest stock focal length; rounding shorter adds croppable margin. Verify image circle, distortion, and corner MTF on the datasheet.
- Calibrate and freezeRecalibrate on the production lens, lock the focus ring, and document the configuration. There is no longer a focal adjustment point left to drift; thermal focus shift is the residual variable, covered in the tradeoffs section below.
The expensive mistake is not choosing an adjustable lens; it is never re-deciding. The varifocal was on the prototype, it worked, and it shipped. Every unit now carries a mechanical adjustment point that vibration, temperature cycling, or an accidental bump can move, plus the optical compromises of a range design, in a system whose geometry stopped changing months ago. Keeping an adjustable lens in production is legitimate when field reframing is a requirement; as a default it is an unpaid liability.
Why do fixed focal lenses often outperform adjustable lenses?
A fixed focal lens is corrected for one focal length, one conjugate range, and one image circle, so every element curvature, spacing, and glass choice targets a single operating point. Adjustable lenses spread that correction across a range. The gap appears at the range extremes and at the image corners, exactly where measurement applications need contrast.
Sharpness and MTF
Center-field MTF on a compact varifocal or zoom is often acceptable; edge and corner MTF at the shortest and longest settings is where the compromise lands. Applications that read barcodes near the frame edge or measure features across the full field should compare corner MTF at the operating aperture, not center-field marketing numbers. The MTF guide covers how to read the curves.
Distortion stability
Distortion on a fixed focal lens is one property of one design: measure it once, correct it in software, and the correction stays valid as long as the lens is untouched. On an adjustable lens the distortion profile changes across the range, commonly from barrel at the wide end toward pincushion at the long end. Any focal adjustment in the field silently invalidates the stored correction. The low distortion lens guide covers how much residual distortion different tasks tolerate.
Mechanical drift and repeatability
A varifocal holds its setting with a friction band or set screw, which is adequate on a bench but less certain across years of vibration and thermal cycling on a production line. A fixed focal lens has no focal adjustment to drift. For motorized zooms, two specs rarely printed on datasheets decide production fitness: magnification repeatability, whether returning to a commanded position reproduces the same field of view, and centration stability, whether the image center walks laterally as the zoom moves. Test both empirically (cycle the zoom through its range, return to the nominal position, and measure the shift) before building a calibrated system around motorized reframing.
Thermal behavior across mount types
Temperature swings move focus on every lens by changing the spacing between elements and the refractive index of the glass and, on plastic-hybrid designs, the plastic elements themselves. Because plastics have higher thermal expansion and index-change coefficients than glass, a glass-plastic hybrid can show a larger thermal focus shift than an all-glass design unless it is deliberately athermalized to offset it. Rely on the lens's rated operating-temperature range rather than inferring thermal stability from construction. A fixed focal lens sees one focus shift at one operating point, and a well-specified industrial lens is designed so that shift stays inside the depth of field across its rated temperature range. An adjustable lens carries a thermal shift at every focal or zoom setting in use, and the magnitude generally differs across the range, typically largest at the long end. Because an adjustable lens is used at multiple settings and often carries more air spaces and moving groups, its room-temperature calibration may drift further from the field condition than a comparable fixed focal lens over the same temperature swing, though the actual difference depends on the specific design. That is one more reason a locked adjustable lens should be re-verified after it settles into its actual operating environment, not just after the zoom ring is set.
Ruggedization (sealed housings, extended temperature ratings, and shock and vibration testing) is a property of specific product lines within a mount family, not a property of C-mount or M12 as a whole. Neither mount type is inherently ruggedized; check the individual datasheet for ingress protection rating and operating temperature range rather than assuming the mount implies an environmental spec.
The recalibration bill
Every focal-length change on an adjustable lens in a calibrated system triggers the same sequence: refocus at the working distance, recapture intrinsics (distortion coefficients, principal point, focal length in pixels), re-verify pixel-per-mm scaling, and revalidate the inspection logic against reference parts. In a lab this is an afternoon. In production it is a documented, scheduled, quality-controlled maintenance procedure, a recurring cost that a fixed focal lens deletes entirely.
Fixed focal lenses are also the cheaper path at equivalent aperture and sensor coverage: a $39–$149 fixed focal typically replaces a prototyping zoom in production at better image quality. Commonlands stocks a broad M12 lens range in the US, roughly 70 lens models spanning 0.8mm–100mm focal lengths, so the calculated focal length usually exists as a stock part. Orders placed before 12 PM PST ship the same day from San Diego.
Do M12, CS-mount, and C-mount zoom lenses differ?
Yes. Zoom and varifocal options are common in C-mount, present in CS-mount, and comparatively rare in M12, where fixed focal designs dominate. The mounts also focus differently: a fixed focal M12 lens is a rigid assembly focused by threading the whole lens in its holder, while C-mount lenses focus through an internal cam that moves element groups.
That distinction matters more than the thread size. The C-mount cam is a compensating system: as the groups move relative to each other, they rebalance aberrations across the focus range, which makes C-mount more forgiving at short working distances. C-mount working distances vary by product, typically 100mm to infinity; the CIL532 12mm C-mount lens, for example, is specified sharp from 100mm to infinity. Many C-mount lenses add an adjustable iris, so depth of field can be tuned by stopping down, which is practical in machine vision because illumination is usually under program control. The C-mount guide covers the cam and iris mechanics.
Fixed focal M12 (S-mount) lenses have no internal moving groups: they focus by thread depth, typically carry no iris, and cover a focus range of roughly 50mm to infinity uncorrected. The payoff is size, mass, and simplicity: grams instead of tens of grams, which decides embedded, drone, and robotics designs. M12 zoom lenses exist but are exceptions; the CIL461 packs a 7X range into a much heavier barrel than a fixed 12.5mm M12 lens. Details are in the M12 lens guide.
CS-mount shares the C-mount thread with a 12.526mm flange distance instead of 17.526mm; a 5mm spacer adapts a C-mount lens onto a CS-mount camera. For zoom optics the flange margin matters: C-mount's longer register leaves more room for back-focus adjustment if the zoom mechanism lands slightly off at the range extremes. Mixing mount families under a zoom lens adds a back-focus variable to a design that already has one; the lens mount guide covers when adapting is worth it.
Why adjustable optics cluster in C-mount
C-mount's longer flange distance and larger barrel diameter give a zoom or varifocal design more physical room for a second moving group, a wider cam track, and, on motorized versions, a motor and gear train inside or alongside the housing. M12's compact envelope was never built around that requirement: the thread itself does the focusing job for a rigid single-group lens, and there is little room left over for a second group to travel independently. That is a packaging fact, not a judgment on either mount. M12's small size and low mass are exactly why it dominates embedded, drone, and robotics designs where a C-mount zoom assembly would not fit or would add unacceptable weight.
The CIL461 is the exception that proves the pattern: a 7X zoom compressed into an M12 barrel, many times the mass of a fixed 12.5mm M12 lens but still far lighter than a comparable C-mount zoom assembly. Where the application can accept that weight and size premium for reframing flexibility in a small form factor, an M12 zoom is worth evaluating before defaulting to C-mount purely because zoom optics are more common there.
Selecting C-mount or M12 answers a packaging and working-distance question. Selecting fixed, varifocal, or parfocal zoom answers a focus-behavior question. The two decisions interact (adjustable optics are more available and more mature in C-mount), but neither should be decided as a side effect of the other. Confirm mount by size, weight, and working distance first; confirm lens type by how often the focal length needs to change second.
Fixed and zoom lens picks compared
Commonlands stocks one manual varifocal zoom for bring-up and a set of fixed focal lenses for production, across M12 and C-mount. The table ranks them by how an integrator reaches for each: the CIL461 6mm–42mm zoom to find a focal length, then a fixed focal lens to lock it in. The fixed picks run $39 to $149 and hold a single calibration; the zoom trades that stability for a 7X framing range.
How we picked: every lens here is stocked and spec-verified against the live Commonlands catalog, and each row reuses only the focus, distortion, and recalibration behavior described earlier on this page. The ranking follows the prototype-to-production workflow, zoom first for framing and fixed focal once the geometry freezes, not raw image quality.
| Rank | Type | Lens | Mount and EFL | Calibration and repeatability | Best fit |
|---|---|---|---|---|---|
| 1 | Zoom (varifocal) | CIL461 | M12, 6mm–42mm, F/2.5 | Refocus and recalibrate after any focal change. Lock both rings once the framing is set. | Bring-up: sweep the range at the real mounting position to find the focal length. |
| 2 | Fixed | CIL059 | M12, 5.9mm, F/1.7 | One -4% distortion profile. Calibrate once and it holds while the lens is untouched. | Wide, locked production geometry on 1/1.7-inch sensors up to 8MP. |
| 3 | Fixed | CIL125 | M12, 12.5mm, F/2.4 | No focal adjustment to drift, and a 7g body keeps mounting stress low. | Telephoto framing on weight-limited embedded, drone, and robotics builds. |
| 4 | Fixed | CIL522 | C-mount, 12mm, F/1.4 | The iris tunes depth of field, not field of view, so a stored distortion correction stays valid. | Faster-aperture C-mount for lower light at 4.2µm pixel pitch. |
| 5 | Fixed | CIL532 | C-mount, 12mm, F/2.0–F/16 iris | Stopping down changes depth of field only; the fixed EFL keeps calibration stable, sharp 100mm to infinity. | 2/3-inch 12MP production work that needs iris control on the line. |
| 6 | Zoom (varifocal) | CIL436 | M12, 4mm–9mm (2.25X) | Refocus and recalibrate per setting. Carries -65% barrel distortion at the wide end. | Wide-angle reframing during bring-up; correct the distortion before any metric task. |
For motorized C-mount zoom, vendors like Computar and Fujinon carry deeper catalogs. The fixed focal picks above are where Commonlands competes, on published MTF, US stock, and price. Verify a candidate focal length in the field of view calculator before committing a purchase order, and cross-check depth of field with the depth of field guide if you plan to stop a C-mount iris down.
The workflow maps onto this set directly: the CIL461 finds the focal length during bring-up, and a fixed focal lens locks it in for production. Contact engineering for current availability on the CIL436 wide zoom. Pair the chosen lens with the right focal length selection and confirm image circle against your sensor before ordering.
Häufig gestellte Fragen
What is a fixed focal length lens?
A fixed focal length lens has one effective focal length, set at manufacture. It cannot zoom; for a given sensor it produces one angle of view. Fixed focal does not mean fixed focus: most industrial versions include a focus ring that is set at the working distance during installation and then locked.
What is a varifocal lens?
A varifocal lens has a mechanically adjustable focal length, but focus does not hold through the change. Turning the zoom ring shifts the plane of focus, so the focus ring must be readjusted after every focal-length change. The two controls are decoupled, which is what separates varifocal from parfocal zoom designs.
What is a zoom machine vision lens?
A zoom machine vision lens changes focal length while a compensating optical group keeps the image in focus. It reframes a scene without a refocus step, manually or by motor. True zoom designs cost more than varifocal lenses because the coordinated group motion requires more elements and tighter mechanical tolerances.
What is a parfocal lens?
A parfocal lens maintains focus while its focal length changes. The term names the focus behavior, not the presence of a zoom ring: a compensating group cancels the focus shift as the zoom group travels. A varifocal lens lacks that compensation and must be refocused at each new focal length.
What is the difference between a varifocal lens and a zoom lens?
Both adjust focal length; the difference is focus behavior. A true zoom (parfocal) lens holds focus through the focal-length change, so it can reframe mid-operation. A varifocal lens loses focus with every adjustment and needs a separate refocus step. Catalogs blur the two terms, so verify focus behavior in the datasheet.
Are all zoom lenses parfocal?
No. Many lenses sold as zoom lenses in CCTV, consumer, and industrial catalogs are varifocal designs that lose focus when the focal length changes. Treat catalog labels as unreliable: check whether the datasheet states focus is maintained through the range, or bench-test it: set focus, change focal length, and watch sharpness.
Does a zoom lens change effective aperture as you zoom?
Often, yes. On many zoom designs the entrance pupil stays roughly constant while focal length increases, so the f-number climbs toward the telephoto end. A lens marked F/2.8 at its wide end can be several stops slower at full zoom. Exposure or illumination must compensate after any zoom move.
Does changing the focal setting on a varifocal lens require recalibration?
Yes, in almost every case. A focal-length change alters image scale, field of view, and the distortion profile, and it shifts focus. Distortion coefficients, pixel-per-mm scale factors, and homographies measured at the old setting no longer apply. Refocus, recalibrate, and revalidate before the system makes measurements again.
Is a fixed focal length lens the same as a prime lens?
Optically, yes: both terms mean one focal length with no zoom. Prime lens is photography vocabulary; fixed focal length lens is the machine vision term. Industrial fixed focal lenses are specified for sensor format coverage, distortion, and resolution across the image circle, which photography primes typically do not document.
Can I use a varifocal lens in a production machine vision system?
Yes, when field reframing is genuinely required (different part sizes at one station, for example). Lock the rings after setup and budget a refocus-plus-recalibration procedure for every adjustment. If the focal setting will never change in production, a fixed focal lens gives better repeatability with no drift-prone adjustment point.
Lock in the right focal length
Send your working distance, scene size, and sensor part number to our San Diego engineering team, and we will confirm whether a fixed focal lens covers it or a zoom earns its place, including motorized zoom requirements. Orders placed before 12 PM PST ship the same day.