How much is the difference between a lens with only two aperture blades and a lens with only 6 aperture blades?

First of all, the apertures of common cameras are divided into cat-eye apertures and iris-type apertures; the 2-element aperture you mentioned cannot be the same as the 6-element aperture.

The cat-eye aperture consists of a metal sheet with an oval or rhombus hole in the center divided into two halves. The two metal sheets with semi-oval or semi-rhombus holes are arranged opposite each other and moved relative to each other to form a cat's eye. type aperture. Cat-eye apertures are mostly used on simple cameras. An "iris" type aperture is composed of multiple overlapping, arc-shaped thin metal blades. The clutching of the blades can change the size of the central circular aperture. Some cameras can change the size of the aperture by turning a ring on the lens barrel, while some cameras use a microprocessor chip to control a micromotor to automatically change the aperture. There can be up to 18 curved thin metal blades. The more curved thin metal blades there are, the more circular the aperture will be. By designing the shape of the thin metal blades using an electronic computer, it is possible to obtain a nearly circular aperture using only six thin metal blades.

So, two-blade apertures and six-blade apertures cannot be the same type of aperture. Cat-eye apertures are generally used on ordinary digital cameras, while iris apertures are generally used on SLR camera lenses or some relatively high-end digital cameras. If it is an iris aperture, if the aperture is to form a circle, at least 5 blades must be used with current technology. I can’t imagine what effect the two pieces would create!

In addition, the two-piece aperture lens cannot be the same as the six-piece aperture lens. The two-piece aperture is generally used on some ordinary relatively low-end digital cameras. This type of aperture generally does not show the What special effects can only be determined by the size of the aperture and the amount of light passing through.

It won’t produce any out-of-focus diffusion effect (it’s okay at macro)

I can tell you accurately that if these two apertures are really the iris aperture of a SLR, it would be really strange; If it were taken from an ordinary digital camera, there would be nothing strange about the light spots in the night scene, really!