Understanding Inverted Images: Calculating M and f Ratios

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Shackleford
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How do I know the image is inverted?

Reporter photographs an actress. The ratio of the actual height of the actress to the height of the image on the film is

M = hi/ho = .00471

f = .220
 
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Magnification and focal length can both have signs (+ or -). The fact that these are + should tell you things about where the object/image are located (on the same or different sides of the optic) and what type of optic is used (converging or diverging). There's also information available just by being able to say there's an image on film... is such an image real or imaginary? Image orientation (upright or inverted) relates to this.
 
physics girl phd said:
Magnification and focal length can both have signs (+ or -). The fact that these are + should tell you things about where the object/image are located (on the same or different sides of the optic) and what type of optic is used (converging or diverging). There's also information available just by being able to say there's an image on film... is such an image real or imaginary? Image orientation (upright or inverted) relates to this.

M = hi/ho = -di/do

The negative threw me off when doing the calculations.

An image on film is real. This also means that the di is positive. Also, the problem didn't specify whether the image was inverted or not. The professor said I was supposed to know that the image was inverted since it was on the film. How do I know this?