Soft Focus: this simple technique can take much time to master, but can be experimented with simply and cheaply, either with photo excising software or using standard fi1m techniques; and can lead to impressive results.
But let’s start by clearing what I mean by soft focus: Soft focus is the effect by which the edges of the subject(S) in an Image appear III be slightly blurred, or as tile name suggests, softer. A “soft focus” Image is normally composed of a slightly out of focus Image combined with a sharp normally focused Image. It is the combination of these two Images which gives the soft focus effect.
This combination can be obtained both while taking the picture, or as I digital after effect.

The analog technique

I called the technique that does not use a computer “the analog technique” because It is performed on the picture as It Is taken, in the analog world so to speak. This being the case, it allows the technique to be used for both digital and film cameras.
The three pictures below, Figures 1-3 are crude examples of a homemade soft focus filter. Commercial soft focus filters (such as the Cokin A-091 and A-092 filters) are available and their prices range from the very cheap to the very expensive. Whilst they are perfect if they are set to produce the exact effect you want, they are often static, meaning that their properties cannot be changed.
But let’s continue with this basic: homemade Soft focus filter:
A piece of cling film, which whilst not having the mast fantastic optical properties, will do for our purposes, was stretched across a Card frame and then a small amount of washing up liquid was smeared onto the center. The first example, fig 1, was taken without the homemade filter in front of the lens. The second shot, fig 2, was taken by smearing the washing up liquid in a circular motion. While the last photo, fig 3, was taken by smearing the liquid in straight lines across the cling film.
As you can see the effects are quite different.
Please note that when using the filter I am only creating the blurred Image. To create the composite Image manually, you would simply leave a small hole in the middle of the cling film, without any liquid on it. By varying the size or the hole, the balance between soft and hard Images can be controlled and therefore the overall effect can be adjusted. This balance is rather tricky to perfect and even more so when using house hold Items but a wide range of effects as possible.
How did the washing up liquid affect the Image entering the camera? The answer is that the filter “diffused” the light in different directions, much as a light diffuser for lighting equipment does. The liquid that was added on the cling film changed its optical properties making it react slightly differently to the incoming light. The digram below, fig 4, shows how this occurs.
With the first filtered example, the Image is softened in all directions. Take a closer look at the door handles and notice the glow surrounding them. As the diffusing liquid was smeared in a circular fashion, the light was bent in all directions.
In the second filtered Image, the diffusing liquid was smeared only in one direction, horizontally. This had the effect of bending light in the vertical direction, but largely unaffecting light in the horizontal direction. Again, look at the door handles to see the effect.
By varying things Ike tile liquid used, the amount used, smear directions and central hole diameter, you can create a wide range of filters to suit your needs. It is worth trying out this technique if only to satisfy your own curiosity. It takes only half an hour to create the filter and start taking some shots with it.