Doing some research on lenses I have come across the following from Cristopher Perez on the hevanet website:

"After performing this test, I believe I begin to understand why old photos can have those qualities. Small blade number apertures can produce rapidly changing dark to light transitions that can be perceived as "harshness". On the other hand, old lenses tend to have many many aperture blades that define a nearly round aperture shape. This is the single most important influence on out of focus area rendition. Further, I believe it is possible to duplicate this effect with modern optics by simply mounting them in multi-blade apertured shutters."

So a simple question.
As far as these visual affects are concerned what is the number required for the 'many aperture blade' effect?

7?
10?
etc,
And then how old a shutter would one need to put the lens in to achieve this.

Thanks,

Marc