There are many ways to achieve the soft focus effect. There are lots of soft effect filters of all kinds, the more expensive (Zeiss Softar comes to mind) ones cost almost as much as a cheaper soft focus lens. So, as you can see, you can get soft effect from very cheap to very expensive. In the olden days as a poor student, I made my own soft focus filter by applying a light coat of Vasoline on a UV filter. Still others use a stocking to cover a normal lens to soften the light. Which way should you choose to go? Vasoline is messy, soft filters are a nuisance to carry around and use, dedicated soft focus lenses have a narrow application and expensive.
There is a nice compromise.
Enter the Sima SF 100mm f2 soft focus lens. The lens comes with 3 filters that goes in the front of the lens. This filters makes the lens f4, f5.6 and f8. Without the filter, it's f2. This is one of the cheapest, yet the most fun lens I have. Very often turns up on eBay and can be had for about $25. Very cheaply built, this T-Mount lens is made entirely of plastic, even the mount. The lens comes in two parts as tubes. The focusing part has the lens element, and is smaller. It goes into the other, larger tube which has a lens mount. The lens element is very deep into the tube and very hard to clean. The good thing is that this is a soft focus lens, a bit of dust will just add a bit more softness to the pictures! If you must clean it, just put it in the dishwasher, and it will come out nice and clean. Probably the only lens I know of that can be washed without fear.
The lens element is un-coated, and uncorrected, thus giving you lots of aberration -- the colours captured with this lens is unprodictable. What you see on the view finder is almost never what you get. It's kind of a nice surprise, sometimes.
Next part, we will talk about how to use this wonderfully cheap lens.
Sima SF 100mm f2 plastic soft focus lens in its basic parts. Left is the outer tube that houses the inner tube with the lens element (middle), and on the right is the lens filter made of plastic. Larger Picture.