Slides are usually of inferior quality to current digital photographs. For this reason, only those slides whose image content is either of historical value or irretrievable should be digitized. Other motifs should be photographed using the latest technology. 
Technically, photography via DSLR and macro lens works very well, and the subsequent RAW development can even surpass the original visual quality.

Macroscopic images of cytological specimens 

Microscope slides can be photographed quickly and in good quality with the existing equipment as well as diapositives.