| Part No. | Lens description | Excl Vat |
| 54547 | Reduction lens for f = 175mm autoclavable | 281.00 |
| 54545 | Reduction lens for f = 200mm autoclavable | 281.00 |
| 54544 | Reduction lens for Retroskop microscope | 281.00 |
The virtual image produced by a wide field BIOM lens lies a short distance above the lower lens, necessitating a reduction lens to shorten the normal focal length of the microscope.
The focusing mechanism of the BIOM can then be used to adjust the virtual image to lie in the same plane as the new shorter focal point of the microscope.
Subsequent lowering or raising of the microscope will only increase or diminish the field of view without affecting the focus which is controlled by the BIOM.