Calculating the magnification of an optical microscopy system

Question

I have a microscopy system that is set up as follows :

• DSLR with a crop factor of 1.6x ( equivalent to magnification, I believe )
• An adaptor optic, for attach the DSLR to the microscope, listed as a 2x magnification
• An objective on the microscope, currently set at 4x magnification

I've photographed a 2mm object, and found it to be 14.24mm on the sensor ( 3618 pixels long on a 5184-pixel wide sensor with length 22.3mm ). With this, I calculate the whole system's magnification to be 7.12x. I divide by 4 to remove the objective, leaving 1.78, and then divide that by 1.6 for the camera's crop factor, to get 1.113.

This is far below the 2x listed by the adaptor. In addition, the adaptor also states, "depending on your camera, you'll get between 12x and 16x magnification", which is very ambiguous, because the microscope objectives range from 4x to 100x or more.

So, I'd like to know if I'm doing something wrong, why I'm not getting 2x for the adaptor, and where this "12x to 16x" comes from.

Any help much appreciated !

Answer 1

The crop factor does not count in the magnification (it simply reduces the field of view, but the size of objects is the same on the detector).

From your numbers, I do not obtain the same magnification. I obtain 7.78 instead. Dividing by the x4 of the objective makes 1.95, pretty close to the advertized x2 of the adaptor optics.