GB/T 8338-2023Camera shutters - Time measurement (English PDF)

3.1 frontshutter

Shutter inside the lens.

Note 1.The inter-lens shutter can be at the front, rear or middle of the lens assembly, and can be composed of a rotating disk, rotating slats, sliding blades, swing blades, etc. The program shutter can also be included.

Note 2.A common feature of inter-lens shutters is that the entire image area is exposed almost simultaneously.

Note 3.When the shutter and aperture are too far apart, the exposure and shutter speed will differ at different points in the image area.

3.2 focal plane shutter

The shutter in front of the focal plane.

Note 1.The focal plane shutter can be composed of a fixed or variable slit curtain, a turntable, a sliding blade, etc.

Note 2.The basic feature of the focal plane shutter is that the image area is gradually exposed, and the time required to expose the entire image area is greater than the exposure time of any point.

3.3 effective exposure

Te

The best measure of the amount of light falling within an image area.

Note 1.The effective exposure time is defined by formula (1).

te=

Eo (1)

In the formula.

te --- shutter effective exposure time, unit is seconds (s);

H---exposure, that is, the integration of illumination over time, the unit is lux·second (lx·s);

Eo---maximum illumination, unit is lux (lx).

Note 2.At any point in the image area, when vignetting is not severe, the te of the entire image area of the inter-lens shutter is usually the same. For focal plane shutter te

Will vary with W and VC. To facilitate measurement, the formula in Note 1 can be approximated as Formula (2).

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