The Brunel Westbury microscopes are ideal for those who need a microscope for fish disease identification that is also suitable for more wider applications. The Westbury microscopes will not diagnose diseases that the much cheaper SP22 will fail to see, however it is more sophisticated in the way it works and it has the potential for other uses such as for example dark ground microscopy (with accessories) that are not essential for fish disease identification but useful should you wish to extend your knowledge and application of microscopy.
The SP30 is monocular and the SP40 binocular, but in all other respects the microscope stand is the same. The difference in price is caused by the complex prisms needed for a binocular head.
The SP30 has a fully rotating monocular head with x10 widefield eyepiece and the SP40 a pair of eyepieces with full independent eyetube focus and distance adjustment.