Olympus MPlan FL N 5x 0.15 Semi-Apochromat Objective

Update October 2018: I had a chance to test the Olympus 5x MPlan FL N against 9 other 5x lenses, you can see the results here in Closeuphotography.com: https://www.closeuphotography.com/5x-lens-test

Olympus MPlan FL N 5x 0.15 Semi-Apochromat Objective

Part Number: 1-U2M522

Official name: Olympus MPLFLN 5x 0.15 Semi-Apochromat Objective

Objective type: Industrial Metallurgical microscope systems

NA, Nominal Aperture, Effective aperture: This lens has a numerical aperture of 0.15, this is a nominal aperture is f/2.7 and an effective aperture of f/16.6

Focal length: 35mm

Parfocal length: 45mm

 Working Distance: 20mm

Mounting Threads: RMS Thread

Coverage: Field Number 26.5

Optical system: to use Infinity-corrected olympus objectives for photography, a secondary 180mm (or tube) lens is required for installation.

Image Quality

A detailed test of this objective with side-by-side comparisons of 9 other lenses is available here on Closeuphotography.com: https://www.closeuphotography.com/5x-lens-test


These objectives are available for a little less than the Mitutoyo 5x M Plan APO objectives but I would spend the extra $100 or so for the Mitutoyo and get almost double the working distance and real APO correction.

What I Like

-Small size
-Reasonable price
-RMS mounting threads

What I Don’t Like

-Semi-APO correction isn’t anything close to APO correction. Olympus should leave APO out of the model description.
-Not a common tube lens focal length 


These objectives are commonly available for about $300-800 on the used market. I paid $300 for a new lens in the box.