calculate the focal lengthof a lens of power -2.5 d

Focal lengthof lens formula

The performance of a filter is based on what happens to light passing through the filter. The apparent color of light reflected off the surface is not a reliable way to judge the filter's capabilities. Batch-to-batch difference in the apparent color of the coatings or filter substrates can often be easily seen when looking at two examples of the same filter type. The color of the coating does not indicate a disparity in performance. Filters 62mm and greater have a surface quality tolerance of 60/40.

Commonly used in fluorescence applications, a BN532 filter is suitable for use with lasers and laser diodes and is less sensitive to angle of incidence variations than traditional interference filters.