DIFFUSION AND SOFTENING FILTERS
You may have wondered what are these filters for and what is the difference between the two.
Both "diffusion" and "softening" filters are used towards the same objective: to reduce blemishes and wrinkles in portraiture. Make people look better. The soft filter is just a more elaborated diffusion lens.
Before these were mass produced, we placed a stretched fine mesh stocking in front of the lens. What this did was to bend a certain percentage of the light forming the image from its original path and thus defocused it. More recently, these can be obtained as standard optical glass filters, like the Tiffen Softnet series. These function through "selective diffusion." They have a greater effect on small details, such as wrinkles and skin blemishes, than on the rest of the image. The clear spaces in the mesh transmit light unchanged, preserving the overall sharp appearance of the image.
Instead of thinking it through (as we should have all done), it was through plenty of experimentation -and anger from our sisters watching their stockings disappear- that we discovered that the finer the mesh, the more the image area was covered by mesh lines and therefore had a greater effect. Contrast was of course reduced and for high speed B&W film photography it looked very fancy.
Another way to obtain diffusion was to place a glass, in front of the lens, smeared with Vaseline. I built several -very heavy- metal contraptions that attached to the tripod socket of the camera, extending a bracket to the front beyond the lens to hold a window frame, where a flat sheet of glass could be slided from the top. We soon found out that leaving the center clear looked even better, more romantic, by isolating the subject from its surroundings. Eventually all of this came to the ears of manufacturers and now we can buy commercial Center-Spot screw-in diffusion filters.
Hoya, for example, achieves the diffusion through an irregular uneven surface. Cokin's Diffusers 083 or 084 are other alternatives.
A popular type are the concentric ring softeners or Dutto filters; they look like water after you drop a stone into it. Examples of this type are the B+W Soft Focus 1 and 2 and the Marumi Diffuser.
CAN YOU ACHIEVE THE SAME EFFECT WITH PHOTOSHOP?
Yes, but it will take some postprocessing time and skills. I am an avocate to do as much as possible straight in the camera; I really don't have much spare time and much less to spend it on postprocessing.
Another later portrait diffusion type involves the use of small "dimples," or clear refracting shapes -in fact minute lenses- dispersed at irregular distances on an otherwise clear optical surface.
Round or diamond-shaped, these are capable of more efficient selective diffusion than the net type. They don't lower contrast, by tinting shadows, as light-colored nets do. These dimples refract light throughout their surface, not just at the edges like the center spot filter. For any given amount of clear space through the filter, which is relative to overall sharpness, they can more efficiently hide fine details than net filters. The Nikon Soft, Zeiss Softar and the Tiffen Soft belong to this type.
I have never used the Hoya Softener filter myself, but fortunately fellow Nikonian Luca Chichizola (username: Beer) has and he shows us here (above) an image of his charming wife made with an 80-200mm f/2.8 ED AF Nikkor, at about 135mm and f/4 on Kodak Echtachrome E100VS.
Randomly arranged minute lenses on the surface of the acrylic Hoya filter, create a picture with clear focus and soft gradation.
The advantage (for me) of the Nikon Soft over the Softar-type filters, is that by changing the aperture you change the degree of softness, the more open the aperture the greater the effect; the more closed down, the lesser effect. The image at the top of the first page was made at f/5.6, my favorite aperture setting for this filter. An interesting added effect is that highlights are more softened that shadows. Something to keep in mind at the backdrop.
Through optical design, the Softars maintain the degree of softness regardless of aperture so if you need varying degrees of softening, depending on your subject, you do need to keep a series of filters. Some prefer this type since the amount of softness is always the same, regardless of aperture used on the lens.
I use the Nikon Soft 1. The Nikon Soft 2 is just too much for my personal taste. The sample image shown in the previous page was taken with a 35-70mm f/2.8D AF lens with a Soft 1 filter to reduce its ultra-sharpness. This Nikon Soft 1 of mine is now called "the magic filter" by my female friends and it is especially requested, as they love the results.
Unfortunately the Nikon Soft cannot be found in 77mm diameter, so I now have a B+W Carl Zeiss Softar 1.
WHAT ABOUT PHOTOSHOP PLUGINS?
Well, yes. Imagenomic, for example, with its set of Portraiture plugins can smooth out skins from their blemishes. But you will need first to increase sharpening -preferably thorugh a deconvolution tool like FocusMagic to prevent image degradation and artifacts- so you don't loose detail where a portrait most needs it: at the eyes.
Whatever filter you choose ... or not
Have a great time
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