Can you see a car from Space?

You can see the car provided its a clear day and the lens is diffraction limited!!

The mathematics also say that using the same aperture at a distance of 0.25 km the diffraction limited resolution would be 300/80mm

3mm is of the order needed to resolve a number plate on a vehicle at 0.5km!

This is of course without using sub-wavelength or sub pixel image restoring software.

Confocal Imaging

This is used in the analysis of a current problem:

How would you measure the deflection of a wing of the roof of a convertible car using a digital or photographic camera? Can this be achieved?

Problem Specification:

More information about the current work with Jaguar can be found here.

Geometric Distortion

A geometric distortion is created by the physical parameters of the lens. Distortions are characterised as:

In each case the shape of the lens has provided a limit to the resolved image.

A typical resolved image is that of a set of lines. Thus firm resolution is often quoted in terms of lines/mm. Conventional photographic film for example has a resolution from 1 to 100 line pairs/mm.
In the case of a diffraction limited lens, the wavelength of light is the limit of resolution. This is expressed as the Raleigh limit of the Abbe limit of resolution.

Although the f no. of 'conventional' camera lenses are in the range 1.8-22, these numbers have more bearing on the aperture of the lens than the their optical resolution.

Operation of Camera

Single-lens reflex, or SLR, cameras are among the most common in use today. Sing-lens reflex means that the same lens is used to viewing and taking the photograph. The movable mirror between the lens and the film reflects the image on a ground-glass viewing screen while the user adjusts the focus. When the shutter release button is depressed, a spring pushes the mirror out of the way, and the image is recorded on the film. The cameras are popular because users have the options to control elements such as shutter speed, focus and aperture manually or automatically. This option allows photographer to achieve a wide variety of effects with relative ease. The quality of the SLR camera pictures is generally superior to that so-called point-and-shoot camera.

In the SLR type of reflex camera, a single lens is used for both viewing the scene and taking the photograph. A hinged mirror situated between the lens and the film reflects the image formed by the lens through a five-sided prism and onto a ground-glass screen on top of the camera. At the moment the shutter is opened, a spring automatically pulls the mirror out of the path between lens and film. Because of the prism, the image recorded on the film is almost exactly that which the camera lens "sees," without any parallax effects.

Most SLRs are precision instruments equipped with focal-plane shutters. Many have automatic exposure-control features and built-in light meters. Most modern SLRs have electronically triggered shutters; apertures, too, may be electronically actuated or they may be adjusted manually. Increasingly, camera manufacturers produce SLRs with automatic focusing, an innovation originally reserved for amateur cameras. Minolta's Maxxum series, Canon's EOS series, and Nikon's advanced professional camera, the F-4, all have autofocus capability and are completely electronic. Central processing units (CPUs) control the electronic functions in these cameras. Minolta's Maxxum 7000i has software "cards" which, when inserted in a slot on the side of the camera, expand the camera's capabilities.

Questions for this section can be found here

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Page last modified: November 26, 2002