Donut Lenses

Do you like the out of focus look of mirror lenses? The donut look of out-of-focus spots of light and the translucent tube look of lines is because of the donut shape of the mirror lens. If there is a similar iris shape in any lens there will be the same look to out-of-focus background shapes. To do this, place a dot at or very near the iris of any lens. You will get the same look. Back in the 30's a guy by the name of Garuzzo (sp?) did this to get more depth of field. His lenses sacrificed the light coming through the center of lenses but gave more depth of field. Those were all hard lenses. (Any more information about Garuzzo would be appreciated.)

The dot can be supported on clear or skylight gel or by very thin threads. You can punch dots out of black tape. Regular hole punches work. Put the tape on clean hard plastic when punching. Peal off for use.

When you do this you have a slower "T" stop lens and you also have a problem as the iris is closed down. The iris adjustment becomes much more sensitive and it very quickly stops all light when the iris diameter reaches the dot diameter. So you have to calibrate the "T" stop ring mathematically or with a through the lens light meter.

Measure the dot and iris opening area when you put in the dot. The "T" stop is now slower by the area reduced by the dot. Calculate the area of each stop before modification and calculate what the stop of each calibration would be with the dot.

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