MAGUS MA20 Objective

MAGUS MA20 20х/0.40 ∞/0.17 Infinity Achromatic Objective
Infinity-corrected achromatic objective. Magnification: 20x. Aperture: 0.40.

The resolution limit of the 20x/0.40 objective is 0.69µm.
Chromatic aberrations are corrected for blue and red light, spherical aberration for green light, and field curvature for 65% of the field of view diameter.

The objective is infinity-corrected. The parfocal distance is 45mm. When observing with a 10/18mm eyepiece, the field of view diameter will be 0.9mm. The objective is designed to work with specimens with a cover glass of 0.17mm thickness.

The lower limit of the useful magnification of the microscope when observing with the 20x objective is 200x. Any magnification lower than that will not enable you to see the details of the object in the image produced by the objective.
The upper limit of useful magnification when observing with a 20x objective is 400x. Any magnification higher than that is considered useless as it does not provide new details of the specimen. We suggest using eyepieces with magnifications from 10x to 20x with the 20x/0.4 objective.

The objective is suitable for studying details of the structure of a specimen of 1µm or larger over a large field of view, e.g., for Nechiporenko urine analysis.
References and downloads


  • MAGUS Bio 230B Biological Microscope
  • MAGUS Bio 230BL Biological Microscope
  • MAGUS Bio 230T Biological Microscope
  • MAGUS Bio 230TL Biological Microscope


Lens material: optical glass

Objective class by aberration correction degree: achromatic

Tube length: infinity-corrected (∞)

Magnification, x: 20

Aperture: 0.40

Working distance, mm: 2.61

Parfocal distance, mm: 45

Cover glass thickness, mm: 0.17

Spring-loaded: -

Immersion: -

Body material: copper

Mount type: WJ 4/5"*1/36"