When you put an anamorphic lens onto the front of your camera lens, you hope to double the width of the image. (Nothing happens to the height, it's not like a fisheye converter.) The type of lens on your camera, though, is crucial. For one thing, the front element should be smaller than the rear element of the anamorphic. As you zoom back to the wider settings, you'll very likely start seeing the inside of the anamorphic unit... vignetting at the corners of the frame. To lessen this effect the anamorphic should be as physically short as possible. And the zoom lens should be small, like the little Switar or Pan-Cinor Compact lenses, or the smaller TV lenses.
Or use fixed focal length prime lenses with their front elements as non-recessed as possible. I've found that 35mm still SLR lenses can work well on a 16mm movie camera. Also they are easy to join to the anamorphic because their front doesn't rotate during focusing. It is of course essential that the anamorphic stays vertical at all times, unless you're looking for drunken effects.
For 16mm filming the widest possible focal length is about 16mm, depending on all the above factors. That's effectively like 8mm of course in the horizontal plane. Pretty wide. You won't get as wide coverage though with a zoom lens. But don't forget, even long-focus tele images can look very effective in widescreen Scope. The 50mm SLR lens shown on the Bolex below is good for 2-shots of your actors talking, blurring the background. Also effective for distant landscapes such as mountains. Many of the great shots we remember from the widescreen movies have been taken with long focus lenses. Omar Sharif's debut emerging from the mirage in 'Lawrence'... and so on.
Whichever way you fix the anamorphic it must be really rigid and square with the backing lens. The Bolex is fairly easy to adapt using the turret holes for supporting posts. Or a simple bracket from the base of the camera will work. It's also important to have as little air space as possible between the two lenses... it helps stop vignetting and improves definition. Also the gap should be light-tight, maybe use an old rubber lens cap or something. On the set-up shown, it is not strictly necessary to use turret posts or a bracket, as I've made a separate adaptor to hold the anamorphic onto the non-rotating SLR lens. But it needs to be really firm.
For focusing I usually estimate the distance and set both lenses accordingly. Then check the image in the reflex finder. I am constantly amazed at the image sharpness obtained with the Kowa. If there is a difference in quality when using it I can only discern a slight lessening of contrast. Otherwise it looks like a normal sharp unsqueezed image. However, it does tend to reduce the depth of field. So correct focus is a must. Exposure: I normally allow about a third of a stop for light absorption within the anamorphic. A large lens shade is good to avoid flare. The Bolex matte box is ideal.
You will of course see a squeezed image through the reflex finder. Usually, composing the picture is not harder than normal. But it's handy to have another "director's finder" to decide the composition before filming. This can be masked for Scope.
Projection can be done using longer anamorphics, as the backing lens is usually not that wide an angle. A simple bracket can hold the anamorphic precisely in position. Set the anamorphic's scale to the screen-distance. Then focus the projector normally. Make slight adjustments if necessary. A good projector lens is essential as any defects are magnified.
