# Tube lens

- Focal length: 50mm
- Outer diameter: 12.7mm
- Material: glass
- Lens type: cemented achromatic doublet

The microscope is designed to use finite-conjugate microscope objectives. However, it is necessary to shorten the distance between the objective and the sensor by inserting a lens in the intervening space. This is not placed one focal length from the camera (as it would be in an infinity-corrected design) and so isn't really a tube lens - think of it as a "tube length correction lens". T

e.g. ThorLabs part number AC127-050-A