Maximum aperture of photographic operation

The aperture value marked on the lens generally refers to the maximum aperture of the lens, and the minimum aperture is generally not marked on the lens model.

Take F 3.5-6.9 as an example, that is to say, the maximum aperture at the wide-angle end of the lens is F 3.5, and the maximum aperture at the telephoto end is f6.9. ..

In other words, if the aperture is at the telephoto end, it will not exceed f6.9 in any case. According to your question above, it is impossible for the telephoto end to reach f3.

In addition, regarding the minimum aperture of the lens, the minimum aperture of most SLR lenses is between f 18 and f36. The specific lens depends on the lens parameters, which is not obvious from the lens model. Generally, the lens can reach the aperture of f22, so the aperture of f 16 or f22 can be used normally.

Most SLR/micro-single lenses are adjustable in aperture, which can generally be adjusted on the fuselage, but some manual ptz need to be adjusted on the lens. There are also some cheap telephoto lenses, the aperture is not adjustable, that is, there is no aperture blade, and the aperture is fixed at a value.