How to calculate microscope image size

[@Sp4ACEC4d3t]

I found it very useful specially for the calculation of the size of an image! Thanks a lot!:D

[@thischannelisdead5303]

what does it mean when the lens says 40/0.65?

[@Biomedengg]

ya

[@kofipapa2886]

Diameter is 2mm and radius also same😅?

[@amanjhariya1102]

It is looking like 10yrs old video