From: Chuck Cole [mailto:firstname.lastname@example.org]
Sent: Wednesday, May 13, 2015 9:39 AM
To: 'FSSP Camera Club'
Subject: Portrait filters and soft focus effects
In his excellent talk on portraiture, Leon only mentioned the diffusion filter as if it was the only type (note: not "diffraction filter" different type that sometimes has similar effects). Perhaps in this day of using extensive Photoshop manipulations, one filter is enough, but there are about a dozen types and they have different image effects. I won't attempt to describe all, but Chris Weston's book on filters can often be bought as "new, old stock" for under $10 from eBay and such. Chris describes all types and their differences. The Tiffen filter book is good also. Tiffen is a high-quality US brand typically used by Hollywood film makers.
Two simple DIY techniques were commonly used in film photography days instead of commercial filters.
A "lumpy" coating of Vaseline on a UV filter has softening effects that can be "adjusted" by the amount and "lumping" of the Vaseline. This is messy but can be washed off. A variant of this is to put clear nail polish on a UV filter, and make that "lumpy". This is not messy but not as easy to wash off so often left on an inexpensive filter.
Placing a woman's stocking over the lens and holding it in place with a rubber band is a good and popular technique that comes off easily.
The many portrait filters include ones with central spots and some that cause vignetting effects and so on. Minolta once made a portrait filter set that had several degrees of softness. Those sets are prized rarities today. The advantage of using filters instead of Photoshop is being able to see or select or adjust the effects at the time of shooting. Much has been written about soft focus photography, and much is online.
I think "classic darkroom effects" like vignetting and dodging look better that most filter or Photoshop effects, but circumstance and personal opinions must rule :-)
Soft focus in a lens is usually achieved by having excess or adjustable spherical aberration in the optics... which is something one usually pays more to get rid of :-)