Quote Originally Posted by Peter De Smidt View Post
Neat, Arri. I'd never heard that about the aperture shape. Did the filter lead to less of a soft focus effect?
I try to explain it, not so easy.
First we have to talk about the kind of soft focus.
The US American favorite of soft focus is in the tradition of the pictoralism, I don´t value it, it is always the view of the photographer.
The central European photographers prefer a kind of soft focus with a sharp core and an halo around it.
This halo is found only when the lens gives a sharp ground image. This is possible with a single lens but only at f/8 and below, the halo has the most beautiful shape at this aperture.
A more of stop down is only for more ground sharpness, the halo getting smaller and smaller. It can be necessary when you work in cloese ups.

This halo delivers a special DOF it is larger than an anastigmat shows.

When you use a circle round aperture with this lenses you getting an ugly halo band which looks more artificially, maybe placed by Photoshop, f.ex.
When a star form shape aperture is in use the light passes in different diameters through the lens and the halo getting more a 3D effekt, is smaller and more soft and runs smooth from the bright objects into the darker parts of the picture.

When you have a look to my picture you can see this halo right of the head, you can see that it is not like a band in one brightness, it has a stepless greyscale and seems to go into the depth and not to the sides.

Thats the reason why a star shape aperture should be use. The Imagon uses a similar system with the two rings of sattelite bores, it has the same effekt but with the advantage of a stepless setting.

This knowlegde seems to be forgotten but in the 1930th-1950th this star apertures were offen in use.

The most of the shown soft focus pictures are not really one, this pictures are offen only unsharp, foggy and weak but not soft.

I find it very interesting that the soft focus lens designs went so different ways.

The central European photographers which are in the tradidion of the "New Objectivity" never accept this all over weak pictures but they use the smooth kind of softness in the pictures.
They don´t like the 100% sharp objects in the room in front of an unsharp background and a 100% sharp picture from near to far were not the goal for all images.
The Imagon or the Perscheid lens, the Rodenstock Eurygon, the Hungarian Duto filters, the Wessely lens and the Softar filters are in this tradition.

That is the reason why you don´t find US American soft focus lenses in Central Europe.

Only in our days some phtographers want to try this lenses and buying it in USA or Japan.

I don´t like lenses like the Veritar or the French Eidoscope.

I´am more in the tradition of the Hungarian, Chech, Russian, Austrian, German and Scadinavian photographers.

Two philosophies and not always the differences are clear visible but when you know it you can see it.