View Full Version : soft focus lens conversion

Allan Fontanilla.com
21-Jun-2000, 01:35
After reading Phil's article on soft focus lenses where perforated disks are ins erted between the lens elements (specifically Rodenstock Imagon,) I noticed that the manual that came with my Fuji f/9 240mm apparently shows a lens (f/5.6 250m m) with these disks as an option. Am I correct or is this used for some other e ffect? Can this be done with the f/240mm- to convert it from a standard to soft focus lens? The manual is written in Japanese, which I cannot read and I may b e completely wrong. I would appreciate any info from those who might know. Than ks

Bob Salomon
21-Jun-2000, 08:37
You must have misread the article.

The Imagon uses disks in FRONT of the lens. It would be impossible to put them inside the lens and if you could they wouldn't do anything.

Dominique Cesari
21-Jun-2000, 12:10
The 250 mm f 5,6 Fuji lens is a soft-focus lens. There is also a 180 mm f 5,6 soft-focus Fuji. I haven't accurate info on them, but they are probably designed in the same way as original Imagon, i.e. undercorrected doublet.

It isn't enough to add perforated disks in front of a normal lens to get a soft-focus lens. Using a soft-focus lens without its disks doesn't transform it in a normal lens : the image is blurred and you can't find a real focusing point. Basically, you need a true soft- focus lens.

N Dhananjay
21-Jun-2000, 17:09
A soft focus lens is designed to be undercorrected. That is, a good amount of spherical aberration is left uncorrected in the design. Spherical aberration is caused when light rays coming through the center of lens are brought to focus at a different point from the light rays coming from the edges of the lens. The perforated discs are used to vary the amount of soft focus effect that you can get i.e., by changing the amount of light coming from the edges of the lens. Place a disk with smaller holes in it and most of the light hitting the film is through only the center and you get a sharper image. Place a disk with larger holes in them and more light from the edges is reaching the film and there is more spherical aberration. You cannot convert a regular design lens (which has been corrected to reduce spherical aberration) to a soft focus one by tossing in these discs. You could try using Softars or the Pictrol diffusers to get a soft focus look (although a true soft focus lens produces a different look - more like haloing with a sharp image superimposed with a softer image). You can also try looking for some older used portrait lenses. Good luck. DJ