Smallest Dimension

Smallest dimension is frequently not an issue except in certain industries, but it defines the complexity of the lens design.

An over simplistic way of thinking about resolving power is the ability to distinguish an object from its surroundings. Due to optical properties of the lens, as detail gets smaller, the image of the detail, softens (or blurs). The lack of resolving power is where the object essentially "blurs" into its neighbors and there is no discernable edge, therefore you can't "see" it.

Just before this final blurring is a critical size called threshold resolution (anything smaller and it disappears). The resolution of many lenses are specified as "line pairs per mm". The line pair is one dark band and one light band, and threshold is where one band (depending on the type of target) blurs to almost fill in its neighbor. Not a crisp image, but viewable, and the dark band is the limit of resolution of the lens.

Note: it is important to remember that, at this fine of a detail, the taking lens will pick up the detail, but due to the blurring, it will appear at nearly double size to the rest of the lens system (a one micron object would appear to be 2 microns entering the zoom system). This phenomenon only applies to the very fine detail. Also, any detail smaller than the threshold will expand to the same doubled threshold (a 0.5 micron object would also appear to be 2 microns).

The second part of "seeing" is that, once the lens system has picked up the object, it must magnify it to the point where it covers at least 2 pixels on the sensor. The smaller the object, and the larger the pixel, the higher the magnification must be. Conversely, an excess of magnification will "smear" the object across many pixels, creating a low contrast image.

CCTV lenses, forced to work close, are limited to about 5 microns resolution, and generally work at less than 1X. If a 2X extender is added to the back of the lens, and the sensor has 5micron pixels, then it may be possible to "see" the limit.

Navitar zoom lenses, operating in the macro mode, can go down to 2.4 - 1.6 microns, depending on the model, and 0.6 microns in the micro mode. A major advantage of the zoom lens is that it lets you see a larger field to locate the object and then zoom up to cover the two pixels to resolve it.

Just for reference, 1 micron is .001mm. The human hair is about 100 microns (.100mm) in diameter.

The default value is .05mm (50microns). If there are no specific requirement for resolution, one can leave the default. Each option offered by the Wizard will include the actual resolution limits.