Swivel Tip
Perhaps the most useful aspect of the Frazier lens is its dual swivel-tip design, which allows for unlimited 360-degree global orientation of the taking lenses. Simply put, the lens can be pointed in any direction, even back at the camera operator. The swivel tip incorporates heavy-duty bearings, which make the system extremely rugged and mechanically precise, and consists of two right-angle pivot points which can be turned independently and continuously in either direction. Internally, the image is relayed through the swivel via a mirror and an amici roof-edge prism. "On any piece of optics with a roof-edge," reveals Neil, "the roof has to be made very accurately. Otherwise, you can end up with a double image on the film. The roof angle should be 90 degree plus or minus three seconds of arc, which is very small. Normally, these types of prisms are used in binoculars and other types of instruments that are used by eye. And the eye is actually quite forgiving. In the case of the Frazier lens, however, the amici's roof-edge images to film, so it has to be very accurate."
Naturally, the Frazier's ability to swivel in any direction allows for a great deal of filmmaking flexibility. "There are obvious situations in tabletop work where it can be a difficult matter to even look through the viewfinder," relates Frazier. "But with the swivel tip, it's easy to leave the camera in a conventional setup and put the lens where you need it. Additionally, if you imagine the lens to be like your hand and arm, you can get the lens wherever you can put your hand. I've seen some extra-ordinary things done with the lens just for the comfort of the cameraman!
"You also have added freedom in that the camera itself doesn't have to be level," he adds. "For example, you can even get a level image if the camera is turned on its side under a car, simply by adjusting the image rotator. This system was designed to free up the difficult aspects of cinematography that are either too expensive or time-consuming. You don't want to have a jackhammer cutting holes in the floor to get a lens in a certain position. You can also save the costs of renting additional equipment like Panatates, dutch heads, low-angle prisms and hotheads. I have gotten reports back from other cinematographers that by using the Frazier lens, they've been able to literally chop days off their shooting schedules."
Image Rotator
The Frazier lens system is the first ever to offer an image rotator, which can be operated manually or by motor. Its ability to rotate the image a full 360 degrees or more — both clockwise and counterclockwise — can be used in a number of ways, ranging from a simple dutch to a complex tabletop move that simulates aerial banks and yaws, or a dramatic crane shot. However, the device is also useful for various practical applications, such as leveling the camera on a hill without tweaking the tripod or dolly, or correcting the image orientation when the Frazier's head is swiveled.
"Rotating an image with a prism is not a new thing," Neil concedes, "but by putting that function in this system with its large depth of field and a fully adjustable swivel tip, you create a new range of options. The image rotator is actually what is called a pechan prism. A pechan prism is common in other optical instruments, but in this case it had to be made to very tight tolerances. One reason for that, of course, is image quality, but another is that we have to keep the boresight constant. If you rotate the prism, you don't want the picture to spiral around too much."
Filter Slot
One feature that was added to Frazier's original prototype is an in-line filter compartment that accepts standard 40.5mm glass filters. With a separate rotating filter holder, one can even externally adjust a polarizing filter.
"Every lens has to have some sort of filtering capability," states Neil. "However, if you put a filter in front of the Frazier's taking lens, you have to be careful about dust. I'm talking about things like tiny carpet filaments flying in the air that are attracted to the glass due to static charge. Therefore, with the Frazier lens, the best place to put a filter is inside the system, within the relay optics. The Frazier's filter slot is also a sealed unit — there are two glass windows inside to prevent dust from traveling up or down the tube — so you can have dust go into the filter compartment without producing spots on the film."
Into the Infinite
The Frazier lens system has become a popular device not only for tabletop work and commercials, but for music videos and features as well, including such films as Titanic, Small Soldiers, Mouse Hunt, Men in Black and Saving Private Ryan. And by covering the Super 35 aspect ratio, the system can be used for a wide range of film work. "Covering Super 35 was a main objective in our design," Neil expounds. "Since we presently don't have a true anamorphic version of the Frazier lens, we felt it was important for this lens to cover all of the regular spherical formats, including Super 35 and Academy. That way, if you're shooting an anamorphic film, you can extract the 2.40:1 frame from the film. However, the system doesn't completely cover full aperture.
"There is a good reason for not having the lens cover the full aperture," he expands. "For every little bit of extra image size that's required, you need a proportional increase in the size of the pechan and amici prisms. The pechan has a certain geometric ratio between the vertical, the horizontal and the thickness, so if you want to increase the image size by 20 percent, you're actually talking about increasing the prism's volume by 73 percent; which is close to doubling its size."
With the existing inventory and continued manufacture of more Frazier lens systems, Panavision can support an increasing number of customers who wish to rent the lens anywhere in the world. Additionally, Panavision and Frazier are making further enhancements to the system, beyond merely adding more lenses. The company is currently working on a motorized version of the lens which will control the pan and tilt of the swivel tip, operation of the image rotator (which will be interlocked with the swivel tip to provide image-orientation correction while swiveling), and focus and T-stop adjustments. Neil notes that this motion-control model should be available later this year. Frazier also reports that he is currently working on several significant enhancements to make his invention even more versatile and "address the needs of present and future cinematographers around the world and into the next millennia."
A version of this story will be available on the ASC Website featuring Quicktime movie clips demonstrating the capabilities of the Frazier Lens.
AC would like to thank Dan Hammond and Jim Roudebush of Panavision, Rosemary Pierson and Curt Cressman of Eastman Kodak, and Bud Stone, Beverly Wood and Paul Alcott of Deluxe Laboratories for their generous cooperation in completing this story.
© 1999 ASC