Optical system options for Zaber Nucleus microscopes
By Mike Fussell, Life Sciences Product Manager
Published on Dec. 17, 2025
Objective selection is the first decision to make when configuring a Nucleus microscope system. Their optical and mechanical properties drive subsequent component options and will have a major impact on the overall performance of your microscope system.
Objectives are NOT included with Zaber microscopes.
Figure 1. A selection of Zeiss, Nikon and Olympus objectives
Supported Objectives
Zeiss ICS, Nikon CFI60, Edmund 120i and Olympus optical systems use infinity corrected objectives. The optical performance of high-end Zeiss, Nikon and Olympus/Evident objectives is essentially equivalent. Nikon and Olympus systems differ from Zeiss by where in the optical path they perform aberration compensation. The Zeiss ICS system corrects the lateral chromatic aberration from objectives in the Zeiss-specific tube lens, whereas Nikon CFI60 and Olympus objectives correct for all aberrations in the objectives without relying on additional optics. This difference prevents Zeiss ICS lenses from being interchangeable with objectives from Nikon or Olympus. Using 3rd party objective lenses with a Zeiss tube lens is not advised.
While matching objectives and tube lenses is highly recommended, since all aberrations are corrected at the objective lenses in the Nikon and Olympus optical systems, these objective lenses are interchangeable - with a few caveats. Firstly, the objective parfocal distance of Olympus objectives is 15 mm shorter than Nikon. This means that the stage height relative to the objective height needs to be adjusted by 15 mm if the objectives are to be interchanged. Secondly, the nominal tube lens focal length is 10% shorter in the Olympus system than in the Nikon system. As the final magnification of an objective is dependent on the ratio of its focal length to the tube lens focal length, this results in the final magnification of Olympus objectives being reduced by 10% if used with a Nikon tube lens.
| Optical System | Tube Lens / Camera Mount | Tube Lens Focal Length | Parfocal Distance | MKR Supports | Objective Thread Type | Objective Adapter |
|---|---|---|---|---|---|---|
| Zeiss | MTC90C/D* | 165 mm | 45 mm | AB249 | M27 | AM171M |
| Nikon | MTC90N | 200 mm | 60 mm | AB176 | M25 | AM172M |
| Olympus | MTC90L | 180 mm | 45 mm | AB249 | RMS | AM173M |
| Mitutoyo | MTC00N** | 200 mm | 95 mm | N/A | M26 x 36 TPI | AM174M |
| Edmund Optics | MTC00M** | 120 mm | Objective-specific | N/A | C-Mount | AM175M |
*MTC90D is required for Zeiss optical system with MJB25 junction block
**Upright Nucleus configurations with MTC00 tube lens and camera mount assemblies are required to accommodate the large size of Mitutoyo and Edmund Optics objectives.
Mitutoyo objectives are frequently used for industrial application and many can provide exceptionally long working distances. These objective use the 200 mm Nikon tube lens. The large size of these objectives means they are generally not recommended for use on inverted configurations. Please contact the Zaber Applications Engineering team if you want to use Mitutoyo objectives on an inverted system. There is no such restriction for upright microscope systems.
Olympus/Evident objectives are frequently selected by Nucleus users with microfluidics applications. At the time of writing, Olympus has the best selection of high performance long working distance objectives which allow users to focus on channels inside a microfluidic chip.
For an overview of objective selection the Zeiss Objective Assistant, Nikon Objective Selector, and Olympus Objective Finder are very useful resources.