Meiji MA558 Auxiliary Lens for EMZ-10 — 0.4X Magnification, 247mm Working Distance

The Meiji MA558 is a 0.4X auxiliary (supplementary) lens designed for Meiji EMZ-10 (and compatible systems noted by the manufacturer). It is typically selected to increase working distance and improve clearance for hands-on inspection—especially when operators need room for tools, tweezers, fixtures, and gloved manipulation. With a published working distance of 247mm, MA558 is a clearance-first configuration used to improve ergonomics, reduce contact events, and support scan-and-handle workflows.

Quick selection note: MA558 is commonly chosen when clearance and coverage are the limiting constraints. Because it is <1X, it typically reduces effective magnification while increasing working distance—ideal for “scan + handle” benches.

Specifications:

Accessory type: Auxiliary lens (auxiliary objective / supplementary lens)
Magnification factor: 0.4X (some listings may show 0.44X; verify to your document-control standard)
Working distance (W.D.): 247mm
Compatibility: EMZ-10 (manufacturer lists additional compatible systems by catalog; confirm to your microscope body)
Mounting: Auxiliary lenses are typically installed by threading onto the objective interface below the microscope head (system dependent)

Where MA558 Fits in Cleanrooms and Laboratories (and Why)

MA558 is a strong fit for cleanroom inspection stations and production QC benches where operators must work under the objective (reposition parts, use tweezers, manipulate fixtures) without colliding with the optics. In practice, long working distance reduces accidental contact events and makes station behavior easier to sustain across shifts.

Typical program fit: scan + handle benches, incoming inspection, packaging checks, dimensional screening setup, and assembly/rework support where clearance is a primary constraint.

Best practice is to separate roles: use MA558 (clearance-first) for scanning/handling, and keep a higher-detail “confirm” station for borderline calls where discrimination is the limiting constraint.

MA558 Features:

0.4X auxiliary lens engineered for EMZ-10 platform configurations
247mm working distance supports tool/fixture clearance and improved ergonomics
Designed for scan-and-handle workflows where operator access under the objective is critical
Supports modular system “engineering” (swap lens factor to tune clearance vs detail)

MA558 Benefits:

Maximum clearance: significantly more space for tools, fixtures, and gloved handling under the objective.
Higher throughput: fewer repositioning cycles and less “fighting the optics” during handling-heavy inspection.
Better ergonomics: long working distance can reduce operator fatigue and stabilize inspection behavior.
Cleaner workflows: reduced contact events help support cleanroom station discipline (covers, wipe-downs, controlled handling).

Common Applications:

Handling-heavy inspection (tweezers, fixtures, gloved manipulation)
Incoming inspection and scan workflows where coverage and access matter
Assembly/rework benches requiring clearance for tools under the objective
General QC screening where a separate confirm station handles borderline calls

Selection Notes (0.4X vs. 0.5X vs. 0.75X vs. >1.0X)

0.4X (MA558): clearance-first for maximum access and workflow speed (effective magnification decreases).
0.5X / 0.75X: balanced clearance and detail where operators still need room under the objective.
>1.0X: confirm/detail configurations where discrimination is the limiting constraint (clearance decreases).

Optics Cleaning (Recommended for Long Working-Distance Benches)

Long working-distance benches often run longer handling cycles, which increases the chance of airborne deposition and film residues on optics. Maintain contrast and reduce inspection noise using optical-grade swabs and specialty low-lint wipers engineered for coated glass.

Link to Meiji MA558 Product Details / Datasheet: Manufacturer Product Page | Datasheet (PDF)

Related Products Available From SOSCleanroom.com

Meiji EMZ-10 Stereo Microscope Body (Binocular) — EMZ-10 platform configuration
Microscope Illuminators — ring lights, fiber optic, and LED illumination (configuration dependent)
Cleanroom Wipers — supports station wipe-down and contamination control

Notes: Treat auxiliary lens factor as a configuration-controlled input. If benches use different lens factors, the same part will appear at different apparent size and coverage—driving inspection inconsistency.

Product page updated: Jan. 21, 2026 (SOS Technical Staff)

© 2026 SOS Supply. All rights reserved.

The Technical Vault

By SOSCleanroom

Last reviewed: Jan. 21, 2026 | Audience: cleanroom operations, QA/QC, lab managers, manufacturing engineering, EHS

Why Long Working Distance Matters in Stereo Microscopy (and How to Keep It from Breaking Your Inspection Program)

Meiji MA558 — 0.4X auxiliary lens, 247mm working distance, scan/handle bench design, and configuration control

Clearance-first configuration Scan vs confirm benches Stereo vs compound education

The one-paragraph answer

The Meiji MA558 is a 0.4X auxiliary (supplementary) lens used on EMZ-10 platform configurations to increase working distance—published at 247mm. Operationally, MA558 is a “clearance-first” tool: it enables scan-and-handle benches where operators need room for fixtures and manipulation under the objective. The tradeoff is that <1X lenses typically reduce effective magnification, so programs perform best when MA558 benches are paired with a separate confirm station for borderline calls.

Program success rule: Treat lens factor as a controlled station setting. If different benches run different factors, your inspection outcomes will drift—even when the product is identical.

Operational problems MA558 is solving

Tool/fixture collisions: insufficient clearance under the objective forces awkward manipulation and slows cycle time.
Contact events: cramped benches increase accidental touch risk (optics, parts, work surface), especially in cleanrooms.
Operator fatigue: tight spacing drives posture strain and inspection variability over long shifts.
Throughput limits: excessive repositioning to “fit” the part under the optics reduces output.

Microscopy education: stereo microscope engineering vs. compound microscope engineering

Stereo microscopes are engineered for inspection and manipulation. They use dual optical paths to provide depth perception and are designed to be modular—stands, illumination, eyepieces, and auxiliary lenses are used to tune a station to the workflow constraint (clearance, coverage, or discrimination). MA558 exists because stereo microscopy is often a production/QC tool where ergonomics and access directly impact repeatability.

Compound microscopes are typically optimized for higher magnification analytical viewing (often slide-based) using a single optical axis and transmitted illumination. Their architecture prioritizes objective/condenser performance and alignment over tool clearance—excellent for analytical microscopy, but not the default solution for hands-on manipulation workflows.

Why this matters: MA558 is not “more power”—it is more clearance. Treat it as a workflow-enabling configuration, not a defect-discrimination configuration.

Best-practice bench model: scan/handle station + confirm station

Programs stabilize when benches are assigned roles. Use MA558 scan/handle benches for coverage, orientation, and manipulation. Then route borderline or defect-critical calls to a confirm bench configured for higher discrimination. This reduces false rejects/accepts and prevents decision drift caused by configuration mismatch.

Configuration control checklist (SOP-ready)

Microscope body model (EMZ-10 series)
Auxiliary lens factor installed (MA558 0.4X)
Eyepiece model/magnification (pair-matched)
Stand type + working height (documented)
Illumination type + standard settings (reduce glare artifacts)
Optics cleaning method and interval (documented)

Optics hygiene discipline (artifact control)

In long-cycle, handling-heavy inspection, optics haze and film residues can be misread as defects. Implement an optics-care routine using optical-grade swabs and low-lint wipers, and avoid reusing loaded cleaning surfaces.

Suggested optics-cleaning SOP insert (template-style)

Remove loose particles before wiping to avoid dragging grit across coated optics.
Use a fresh optical swab/wiper; lightly dampen with minimal approved solvent.
Wipe gently in one direction; avoid heavy pressure and repeated scrubbing.
Replace the cleaning surface frequently; do not reuse loaded swabs/wipers.
Cover the microscope when idle to reduce airborne deposition.

Helpful links

Source basis

SOSCleanroom product listing context (application positioning and bench workflow language).
Manufacturer MA558 product page and datasheet (0.4X factor and 247mm working distance).
Common inspection microscopy best practices: scan vs confirm station design, configuration control, and optics hygiene discipline.

Compliance note: This Technical Vault article is provided for educational support. Always follow facility SOPs, QA requirements, and validation/qualification plans.

Document control: Rev. Jan. 21, 2026 (SOS Technical Staff)