40X Infinity Achromatic Microscope Objective - 0.65 NA Black

Our review of this 40X infinity achromatic objective finds it well suited to biology labs and serious hobbyists who need a compact, precision replacement lens for infinity-corrected microscopes. The single biggest reason to buy is its combination of a true 40X magnification with an achromatic correction and a 0.65 numerical aperture, which together improve color fidelity and resolving power for routine biological work. It installs on standard RMS threads and uses a spring nosecone for safe, parfocal mounting, making it a straightforward upgrade for compatible microscopes.

Key Features

• Achromatic correction: reduces color fringing across visible wavelengths so stained biological slides and cellular detail appear more accurate.
• Infinity-corrected DIN design: fits microscopes with infinity optical systems and preserves the intended tube lens correction for sharp images.
• 40X magnification with NA 0.65: balances reach and resolution for most mid-power biological observations, offering clearer detail than lower-power objectives.
• RMS mounting thread: standard 20.32mm thread and 45mm parfocal distance allow direct compatibility with many lab and teaching microscopes.
• Spring nosecone: protects slides by retracting on contact and helps maintain parfocal alignment when swapping objectives.
• Black finish: durable coating gives a professional look and resists visible wear in routine use.

Who It's For

This objective is aimed at educators, students, and hobby microscopists using infinity-corrected microscopes who need a reliable mid-power objective for biological samples such as prepared slides, tissue sections, and pond organisms. Laboratories that follow DIN standards will find it straightforward to fit into existing objective sets without extensive recalibration.

Users who require high-end plan or apochromatic correction for demanding photomicrography or critical color matching should look elsewhere, as this lens is a well-corrected achromat rather than an apochromat. Also, it is intended for optical systems with an infinity reference; it is not suitable for finite tube-length microscopes.

Pros & Cons

Pros

• Good color accuracy for an achromatic design, improving contrast and detail visibility on biological specimens.
• Standard RMS 20.32mm thread and 45mm parfocal distance make installation simple on compatible microscopes.
• The 0.65 NA provides a solid balance of resolution and depth of field for mid-power observation.
• Spring nosecone protects slides and helps avoid accidental damage during objective changes.

Cons

• Achromatic correction is not as advanced as apochromatic optics, so the most demanding imaging tasks may show residual chromatic aberration.

Specifications

Magnification	40X
Numerical Aperture	0.65
Corrections	Achromatic
Optical System	Infinity
Reference Focal Length	180mm
Mounting Thread	RMS 20.32mm
Parfocal Distance	45mm

Our Verdict

The objective is a practical, well-made 40X achromatic lens that delivers good color correction and resolving power for biological applications at a reasonable value. Buyers with infinity-corrected microscopes and RMS mounts will appreciate the easy fit and reliable performance, while those needing the ultimate in color correction for imaging should consider higher-grade apochromatic objectives instead.

Frequently Asked Questions

Will this work on my microscope with RMS mounts?
Yes, it uses the standard RMS 20.32mm thread and a 45mm parfocal distance for compatibility with many microscopes that accept RMS objectives.

Is this objective suitable for oil immersion?
No, this lens is described with a spring nosecone and achromatic correction for dry biological use; it is not specified as an immersion objective.

Can I use it for photomicrography?
It can be used for general photomicrography on infinity-corrected systems, but apochromatic objectives give superior color fidelity for demanding imaging work.