Calibration of
the Zeiss M35 Photomicroscope Calibration of
the Zeiss M35 Photomicroscope
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The magnification of an image on film in a photomicroscope is
NOT a simple matter.
It depends on the inherent Magnification of the OBJECTIVE,
The Distance between the Objective and the Film in the Camera,
the Magnification of any other lenses (Optivar Lenses or Projection Lens) between the Objective and the Film.
There is a 16X Projection Lens that resembles an Ocular in the Photo-tube of the Zeiss M35 camera system.
However, the correct Magnification can NOT be determined by multiplying the magnifications of the Projection Lens and Objective!
The best way to determine the image magnification is to use a Stage Micrometer.
Stage Micrometer
This contains a finely etched scale of precise intervals.
The Scale represents "The Known" or Constant measurement which does NOT change.
This Scale is 2.0 mm in total Length. It is divided into sections of
0.1 mm. The latter are subdivided into 0.01 mm units. Remember that 1 mm = 1,000 microns.
Pictures of the Scale are made with the various objectives.
Distances between known points on Photos of the Scale are measured with a fine ruler on the resulting Negatives or Prints. These will be called Measured Distances!
A Measured Distance is divided by the Known or Constant Distance to determine the Magnification.
Procedure for a Print
A Stage Micrometer with a finely etched scale of 2mm in total Length (with Divisions of 0.1 & 0.01 mm) is Photographed.
The Distances between Divisions of the Stage Micrometer are Constant.
The length between the Scale divisions on the print changes depending on the magnification of the Objective.
The Measured Distance is obtained with a ruler.
This is divided by the "Known" or Constant Distance to calculate the Magnification of the Print.
Example
If the Measured Distance on a print is 200 mm between
the 0 and 2.0 mm markings on the Stage Micrometer Scale,
the Magnification is therefore 100X
(200 mm/2 mm = 100)
The Picture of
the Scale is 100 X greater than its actual size
(200 vs 2 mm).
Calculate the
magnification of a print if the distance
between
0 & 2 mm = 600 mm?
Magnification = 600/2 = 300X
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