Calibration of the Zeiss M35 Photomicroscope-2

My Calculations for the actual Magnifications of the objectives we used in this class are given below.

These were calculated from 4 x 6 inch prints.

It is best to do this from Negatives or Slides because they have a constant size. Prints can be made at innumerable sizes but the negative & slide sizes will always be the same!

If you use prints it is convenient to make them the same size.

A 4 x 6 inch Print is approx. 4.49 times larger than the Negative.

2.5X Objective

2 mm on the Scale = 115 mm on the Print (115/2 = 57.5X)

The Magnification on the Negative is approx. = 57.5/4.29 = 13.4X

10X Objective
(This should be approx. 4X greater than the 2.5X Objective)

0.45 mm on the Scale = 100 mm on the Print (100/0.45 = 222X)

This is approx. 3.86X greater than the 2.5X Objective
However, 10X/2.5X = 4.0
(The difference between the measured and calculated values is 3.5%)

The Magnification on the Negative is approx. = 222/4.29 = 51.8X

16X Objective

0.45 mm on the Scale = 100 mm on the Print (0.45/100 = 333X)

This is approx. 5.79X greater than the 2.5X Objective.
Based on simple math, the 16X image should be 6.0X larger than the 2.5X image.
16X/2.5X = 6.4X
The differences above would lead to a measuring error of approx. 10%!
This illustrates the need to carefully calibrate the microscope you are using, rather than trusting  the supposed lens characteristics.
The Magnification on the Negative is approx. = 333/4.29 = 77.6X

40X Objective

0.1 mm on the Scale = 90 mm on the Print (90/0.1 = 900X)

This is approx. 16.6X greater than the 2.5X Objective.
Based on simple math the 40X image should be 16.0X larger than the 2.5X image.
40X/2.5X = 16X
The differences above would lead to a measuring error of approx. 7%!
This illustrates the need to carefully calibrate the microscope you are using, rather than trusting  the supposed lens characteristics.
The Magnification on the Negative is approx. = 900/4.29 = 210X

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