Nikon 2177, 1987 user manual Exposure factor, Effective f-number variation P, Setting the aperture

8. Exposure factor

The f-number of a lens indicates brightness of the image formed by the lens set at “infinity” shooting distance. The higher the

En reproduction ratio is, the more the brightness of the image will decrease. The actual brightness of the image is called the “effective f-number,” and the exposure compensation value for the change of the effective f-number is called the “exposure factor.”

9. Effective f-number variation (P. 146)

With this lens, the higher the reproduction ratio is, the more the brightness of the image on the film (image sensing device) will decrease and the effective f-number will increase (the amount of light that comes through the lens´ aperture will decrease). This variation is automatically compensated for by the camera´s exposure meter, so the user can determine exposure or operate TTL flash shooting without having to consider the exposure factor.

The f-number displayed in the camera´s LCD panel or viewfinder is the value automatically compensated.

10. Setting the aperture

Set the aperture on the camera body. When exposure (or shooting) mode is set at “A” (Aperture Priority auto) or “M” (manual), the camera will control to maintain the predetermined f-number (up to approx. 1.6 stops) as the effective f-number varies with shooting distance.

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