Nikon Metrology EDF20031 3x Measuring Microscope objective

Description

Nikon Measuring Microscope objectives, also known as Measurescope Objectives, Toolmakers objectives, TM objectives, or just MM objectives, in this case the MM 3X.
The Nikon MM series objectives offer great image quality and are really simple to set-up and thanks to a long working distance, lighting is really hassle free so they are very easy to use for macro photography. These are my personal favorites,
MM 3X Key Features
Ultra Long Working Distance:
the MM 3X gives you 75mm of WD to light your subject,
Shock-proof and Dust-proof Design:
Nikons MM series are the only objectives that I have ever heard designated as shock-proof.
Telecentric design:
With this lens light rays are parallel to the optical axis in object and image space. This means that magnification is nearly constant over a range of working distances, so perspective error is eliminated so objects farther away appear to be the same size as closer objects. You can turn off scaling adjustment when using stacking software with a telecentric lens.
Image Quality:
The MM objectives are consistent center and corner performance. They are not the sharpest in the center due to the conservative NA but they so make a nice image.