Measuring Field of View (FOV)

[NikonUser]

For low magnification it is relatively simple to use a mm ruler to estimate the FOV.
At higher mag. the 1mm spacings on such a ruler are not very accurate when measuring anything except integer numbers.
Edmund Optics catalog has illustrations of the scale patterns on its glass reticles.
Once calibrated, these scales are a convenient way to estimate the FOV for any lens/extesion.

I photographed one of these printed scales using a Nikon 4x objective on 33cm of extension.
As shown below in the full frame image the FOV covers 7.5 'units' on the printed scale.
Thus the FOV for this lens with this amount of extension is 2.7mm; on the 23.6mm sensor this represents a mag of 8.7x.
This printed scale is divided into units of 0.36mm, a lot better than the 1mm units on a ruler.

NU09228

[LordV]

Cor that takes me back - used to do a lot of photomicroscopy with either Olympus or zeiss photomicroscopes in my younger days. Often made use use of calibration slides. Used to use a wonderful high resolution black and white film called microneg pan B if I remember correctly resulting often in 5 minute exposures when doing fluorescent work .
Brian v.

[NikonUser]

I have a micrometer slide that has divisions as fine as 0.01mm. Markings very pale but works fine on a microscope stage with a microscope setup.
Almost impossible to locate the scale when using high magnification with a camera/bellows/ lens setup.
This printed scale is easy to locate.