Specifications:

• Infinity Plan Achromatic Objective
• 4X Magnification Power / Numerical Aperture 0.10
• Working distance is about 19mm
• RMS thread

The Infinity Objective lens can only work with a tube lens. You can use 180mm focal length lens as a tube lens. The magnification will vary if you use a different focal length. For example with a 250mm lens the magnification will be (250/180)*4=5.55

By using this formula as a reference the Depth of Field = 0.55 / (0.10 x 0.10) = 55 μm

Testing image using 4X Infinty Plan Objective with raynox 150 reversed, 35 micron step length, 22 pictures focus stacked. Resized only.