Lens Options

Any standard C-mount lenses with a 1/2" aperture will fit the MEGA-DCS stereo head. Lenses with variable focal lengths (zoom lenses) are not recommended, since changing the zoom will make re-calibration necessary.

We offer a selection of 1/2" lenses that will work with the MEGA-DCS. Longer and shorter focal length lenses are available on request.

The tables below are useful in determining which lenses will fit the field-of-view and range resolution requirements of an application.

Lens Characteristics

Lens

FOV
(H deg x V deg)

Weight
Grams per pair

3.5 mm, F1.8
Manual iris, fixed focus

95 x 79

140 g

6.0 mm, F1.3
Manual iris and focus

65 x 51

100 g

12 mm, F1.8 (1" aperture)
Manual iris and focus

35 x 27

224 g

16 mm, F1.4
Manual iris and focus

27 x 20

200 g

 

Range Resolution

The resolution of range images produced from stereo is a function of the stereo head optics, imager characteristics, and distance to the object. The chart below show the range resolution for three of the lenses above.

The range resolution was calculated based on a pixel size of 6.0 um, sub-pixel interpolation of x16, and a stereo baseline of 90 mm. The range resolution grows with distance squared. Even at moderate distances, though, the range resolution is excellent. For example, a wide-angle 4.8 mm lens still has a precision of about 2 cm at 5 m.

The formula for computing range resolution is:

dR = .0060 * R**2 / (16*90*L),

where R is the range to the object, and L is the lens focal length. All dimensions should be in mm.