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Specification

Source of data

• Manufacturer's technical data.

Manufacturer description

The Sima SF Lens is ideal for a great variety of subjects and is particularly effective with portraits, landscapes, still-lifes, flowers and foliage. It is a lens you will have to experiment with to determine what type of image will most appeal to your own tastes and interpretive desires. One can become so enamoured with its effects that there may be a tendency to take everything in soft-focus, which can be a mistake! But with use, you will become more selective and will use the lens to its best advantage.

The Sima SF Lens has a fixed f/2 aperture that allows you the opportunity to work in relatively low-light conditions with even some of the slower speed films. And with each lens, there is a packet of accessory aperture discs and a neutral density filter disc to compensate for bright light situations and faster films.

The two aperture discs, an f/4 and an f/5.6, serve a double purpose: to reduce the amount of light in bright light conditions and to give a sharper image and increase the depth of field.

The accessory discs attach to the front of the lens barrel using the mounting ring. To remove the ring from the lens, simply rotate it counter-clockwise to disengage. Slip the accessory disc under one of the locking lugs. Line up the notch in the disc with the other lug, slip it under, and rotate the disc so it is behind both lugs. Then, reattach the mounting ring to the lens barrel.

The mount is designed so that both the neutral density filter and an aperture disc can be used together, if desired.

Accessories Included:

• f/4 and f/5.6 supplementary aperture discs
• ND4X neutral density filter
• Disc mounting ring
• Wallet for accessory discs
• Lens cap

From the Popular Science magazine (January 1982)

Sharpness? Forget it, with the Sima SF soft-focus lens. It's designed deliberately to produce "romantic" and "ethereal" photos. The 100-mm lens has a fixed f/2 aperture, comes with accessory aperture discs and a neutral-density filter disc - all for about $50.

From the Popular Photography magazine (July 1982)

SIMA SF LENS

It takes front disks for up to three choices of soft focus, allows close-ups to two-thirds life-size

• Single glass-element 100-mm f/2 lens
• Removable front ring for mounting f/4, f/5.6 aperture disks, neutral-density filter, all included
• Focusing to 2/3 life-size
• T-type camera mount

The 100-mm Sima SF lens allows one to turn soft, romantic mental images into actual pictures. With its two accessory aperture disks, it offers three degrees of softness.

The greatest amount of softness is obtained, of course, at full aperture, f/2, which also lends itself to available-light shooting. In the center of the picture you'll find a tiny vestige of sharpness that rapidly falls off toward the edges into artistic impressionism.

If you don't wish quite so much softness - and exposure - you can use either of two disks, one with f/4, the other with f/5.6 Waterhouse stops. Naturally, the smaller the opening, the greater the sharpness. But even at f/5.6 you still get that soft glow superimposed on some very definite subject outlines. Moreover, the lens comes with a neutral-density filter that cuts light transmission by 75 percent, the equivalent of two f-stops.

You can focus it rapidly, from infinity down to 1:1.5 or 2/3 life-size, with a push-pull of the lens barrel. You should focus carefully on that part of the subject you wish to be most recognizable ("sharpest"). It will then be surrounded by softer areas.

The disks and ND filter should be adequate for most work, but if you like some change in color rendition, you could cut acetate or gelatin filters to fit behind the front-mounting ring. As soft-focus images tend to look less contrasty than sharp ones, let me suggest that you start your experiments with subjects that have well-saturated colors and contrasty lighting.

The Sima SF looks massive - it is 147.3 mm (5.8 in.) long - but as its lens house and barrel are made of plastic, it weighs only 156 g (5.5 oz.).

Price of the lens is $49.95, and it is made by Sima Products Corp., 4001 W. Devon Ave., Chicago, Il. 60646.

From the Popular Photography magazine (March 1985)

At one time, entering the fascinating world of soft-focus photography required a considerable cash outlay for special optics.

But with the advent of the Spiratone 100-mm Portragon f/4 lens at $34.95 and the Sima 100-mm Soft + Macro f/2 at $60, you needn't break the bank to try your hand in this medium of delicate dreams. Both lenses are fitted to an SLR via a simple "T" adapter.

The Sima Soft + Macro f/2 lens is supplied with small plates containing extra Waterhouse stops of f/4 and f/5.6, as well as a 4X neutral-density filter. All of these are useful for controlling the length of exposure. In addition, the f-stop has an effect on the amount of diffusion and contrast you get. Simply put, the smaller the aperture, the less diffusion and the greater the contrast. (Neutral-density filters do not change the physical aperture size, and therefore do not change the amount of diffusion or image contrast.) The Sima lens focuses close enough to give half-life-size images on film without the use of accessories.

The absolute limit for truly soft images is about f/5.6, with f/8 reserved for pictures with an almost-sharp look.

Lenses with similar focal length