This is a very fine, lightly used Japanese-made Seiwa APO 10x 0.23 M Plan (Correct Tokyo). It comes with a plastic tube case. It works properly. It’s clean inside and out. It’s similar to a Mitutoyo product.

The Seiwa M-Plan APO 10X 0.23 is a precision-crafted apochromatic objective lens designed for high-resolution imaging in visible light applications. Here’s a breakdown of its key specifications and features:

Technical Highlights

Feature Specification

Magnification 10x

Numerical Aperture (NA) 0.23

Working Distance 38.9 mm

Focal Length 20 mm

Resolution 1.5 µm

Depth of Field 5.2 µm

Image Circle 24 mm

Compatible Tube Lens f = 200 mm

Mounting Options M26 or RMS thread

Weight ~215 g