值標度

標在光圈調整環上表示光圈開度大小的數值.f值P通常是按平方值遞減或增加一倍的，相應的光圈面積每格減小一半.光圈的標度分格為：f1、f1。4、f2、f2。8、f4、f5。6、f8、f1、f16、f22等.開度最大時f值最小.有些鏡頭的光圈標度不一定完全相同，但一些較小的光圈數值都是相同的.專業攝影用的多透鏡組合鏡頭，由於光學鏡組本身有吸光作用，因此幾何上的f值並不能準確地反映出真正的透光量，通常用T－格值來表示一個無吸光損失的標準鏡頭的f值. Marked on the aperture adjustment ring, said aperture opening size of the value. F the value of P is usually reduced or increased by the square of twice the value of the corresponding aperture area is reduced by half for eachgrid. Aperture of the sub-grid scale is: f1, f1 . 4, f2, f2. 8, f4, f5. 6, f8, f1, f16, f22, etc.. opening the largest f value of the minimum time. Some of the lens aperture scale is not necessarily identical, but some smaller aperture value are the same. professional photography combined with the multi-lens camera, asopticallens groups have their own absorption effect, so geometry on the f values and not accurately reflect the true amount of light transmission, usually expressed in T-cell values of a non - absorption loss of the f value of the standard lens.