NIKKOR - The Thousand and One Nights No.17

Instruction Manual of PC-NIKKOR for Nikon F

A compact SLR camera has a lot of merits such as rapid shooting, handiness, and economical efficiency. Among them, it is the biggest merit that the subject to be shot can always be seen by the viewfinder through the shooting lens. It has been always expected that a SLR camera might probably become convenient when a tilt-shift photograph of a large-film-format view camera could be obtained by using the biggest merit. However, a compact SLR camera capable of shooting a tilt-shift photograph has not been appeared because not much space could be available and there were tough problems in the optical system. This time Nippon Kogaku K. K. has introduce the world's first PC-NIKKOR for Nikon F capable of easily shooting a tilt-shift photograph with simple handling as an ordinary inter changeable lens (patent pending).

Prenatal Story of PC-NIKKOR

In our company various kinds of trial models as shown in Photo 1 have been studied for past several years. What we aimed at did not miniaturize a conventional view camera, but made the best use of the merit inherent in Nikon F getting one step further.
The model A shown in Photo 1A was able to shift, swing and tilt as an ordinary view camera. The mechanism of this model was very interesting that the kind of tilt-shift movement was almost similar to that of a large-film-format view camera. In other words, not only the optical axis of the lens was able to be moved parallel in the direction of the length, but also the lens was able to be rotated in all directions around the principal point (patent pending).
Then, the model B shown in Photo 1B was manufactured. This model B was designed as a result of study of the model A from various angles, had an almost similar mechanism to that of PC-NIKKOR introduced this time, and had a little unsatisfactory points in optical system, the amount of shift, and some of inner mechanism.
The one shown in Photo 1C is PC-NIKKOR. This has basically different tilt-shift mechanism from that of a large-film-format view camera. The concept is similar to the polar coordinates and sufficient tilt-shift effect can be obtained in all directions with simple operations. "PC" in PC-NIKKOR comes from the first letters of "PERSPECTIVE CONTROL."

Why Do You Need Tilt-Shift Mechanism?

As the reason why you use tilt-shift, the following two objects are considered as the most basic object. One is for correcting perspective, and the other is for focusing at the imaginary plane including two points having different distances from the camera with each other. As for the latter case, since depth of focus of a lens for a small film format camera having a short focal length is extremely wider than that of a lens for a view camera having long focal length at the same f-number, tilt-shift mechanism is not so required except special cases.
As for the former case of perspective correction, it is frequently required by a small film format camera in particular.

In the case of a lens with particularly short focal length, when a subject is aimed upward or downward, perspective is exaggerated, so that people's heads become larger upon shooting downward, or the top of buildings become narrower upon shooting upward. Until now we have thought it unavoidable, so we enlarged it as it was or in order to correct distorted image, we tilted each paper holder upon enlarging. However, this correction was rather troublesome and also had a limit, so, truth is, the correction has not performed frequently. Moreover, in the case of a positive color film, when you project the color slide, you cannot correct perspectives upon projecting as performing monochromatic negatives upon enlarging, so it is necessary that the shot image is not distorted. Therefore, PC-NIKKOR has a shift mechanism for correcting perspective distortion.

Merits of PC-NIKKOR

We set the focal length of PC-NIKKOR to 35mm in consideration of indoor photographs and high-rise photographs. Although the angle of view relative to a diagonal of an ordinary 35mm lens for 35mm film format is 62 degrees, the angle of view of this lens is designed larger angle of 76 degrees. Thus, the covered angle of view is much wider than 35mm film format. In other words, to shift in PC-NIKKOR means selecting preferred perspective by moving 35mm image frame here and there within extensive field coverage as shown in Fig. 1. Accordingly, deformation of shot image can be prevented by holding the image plane parallel to the object plane
PC-NIKKOR does not require a level. Nikon F has the construction that focusing screen can be changed easily. When a focusing screen with grid patterns is used and vertical and horizontal lines of the subject are aligned with the grid lines, the subject and film plane can be kept parallel through the viewfinder without using a level.
Accordingly, since you can easily position your camera without help of a tripod, you can lightly shoot a shift photograph from anywhere such as narrow scaffolding of a construction site or a window of a car.

In a finder screen of ordinary view camera, direction of image is reversed up and down, right and left, so the reversed image is difficult to perceive. In the case of Nikon F, an enlarged erect image can always be seen with the help of eye-level finder including a pentagonal prism. When you shoot with holding your camera near the ground, you can change the eye-level finder to a waist-level finder.
Tilt-shift operation of a view camera is divided into each individual operation such as rise, fall, shift, swing, and tilt. Although amazing result can be obtained with proper operations, you have to be practiced considerably. On the other hand, in order that even a beginner may operate readily, the operation of PC-NIKKOR is carried out by turning only one knob for shifting the lens along a V-groove formed perpendicular to the optical axis. The direction of shifting can freely be chosen from any direction of 360 degrees. Accordingly, turning the single knob can carry out shifting even in slanting direction.
It is also a merit of the lens that when you do not use shifting, you can use the lens similar to an ordinary lens and is not bulky. Photo 2 is a side view and a rear view of PC-NIKKOR upon shifting. Photo 3 is a side view and a rear view of PC-NIKKOR without shifting.

Structure of PC-NIKKOR

Optical system of PC-NIKKOR has 6 elements in 6 groups as shown in Fig. 6 having the focal length of 35mm and the maximum aperture ratio f/3.5, and designed with sufficient resolving power within a proper shifting range and not producing insufficient light quantity in practical use.
The maximum value of the proper shifting amount defers in the direction of the image frame as shown in Fig. 2. The lens barrel structure shown in Fig. 3 is composed of a mounting portion to Nikon F camera, a rotating portion for setting the direction of shifting, a shift adjusting portion, a focusing mechanism, an aperture-operating portion, and lens chambers.

Shift direction can be set to any direction with regard to the image frame. For your convenience, click stops are set at every 30 degrees. Shift amount adjustment is carried out with a rotating knob and its amount is indicated on the scale marked in millimeters located upside of the lens barrel. The aperture stop is a preset aperture stop with 8 steps at even intervals up to f/32. Focusing is carried out with linear double helicoids as the same as Nikkor Auto lenses and has the close-up distance of 0.3 m.

The colors of the depth of field scales are corresponding to those of the aperture scales. The depth of field is shown in Table 1. As for the focusing screen, a grid-patterned focusing screen with a Fresnel lens is prepared.

Swipe horizontally to view full table.

Effect of PC-NIKKOR

When you use PC-NIKKOR, you can change shooting range of a subject without moving your camera. For example, when you shoot a high-rise building from the ground, the top of the building becomes narrow as shown in upper photograph of Example 1. When you shoot from the same position with your PC-NIKKOR shifting upward, all vertical lines of the building become straight without distortion as shown in lower photograph of Example 1.

Thus PC-NIKKOR can prevent distorted image. Moreover, using this function you can shoot connecting photographs of a really wide range. In conventional connecting photographs, you have to shoot changing direction of your camera, so it is difficult to connect overlapped portion. In particular, it becomes very difficult when the subject is located at close distance.

On the other hand, when you use PC-NIKKOR, you firmly fix your camera on a tripod, shoot a first image with shifting the lens in desired direction, rotate the lens to the opposite position and shoot a second image. These two photographs are smoothly connected at a certain position, so you can obtain a connecting photograph of a really wide range.

As you notice from Fig. 4, when you shift in the vertical direction (facing to your camera), you can obtain the maximum area of the subject with the minimum overlapped area. When you apply the maximum amount of shift, the connected angle of view in vertical direction is 65 degrees, and that in horizontal direction is 78 degrees. These values are really wide angles in comparison with an angle of view of each wide-angle lens shown in Table 2. Examples 2 and 3 are photographs showing these cases.

Swipe horizontally to view full table.

How to use PC-NIKKOR

As same as an ordinary interchangeable lens, PC-NIKKOR can be mounted to a Nikon F camera by placing with the mounting index of the lens to the lens mounting index in front of the camera, pushing the lens inward and twisting the lens anticlockwise about 58 degrees. At first choose exposure and set the aperture value by turning the aperture-preset ring. The preset ring can be turned with pushing the ring to the camera. The aperture ring is turned to full-open (f/3.5) side to be able to obtain bright view of your subject. After selecting horizontal or vertical framing position in accordance with the subject, turn the lens to the direction intending to shift with the help of grid patterns in the viewfinder, and correct the perspectives by turning the shift-adjusting knob. Then, focus the subject by turning the focusing ring, turn the aperture ring until the preset aperture value, and push the shutter release button of the camera. Although the maximum value of the proper shifting amount is shown in Fig. 2, the shift-adjusting knob can be moved up to 11mm in each direction. When a conspicuous subject is not there on the periphery in the shifting direction, in other words, there is the sky, the ground, or a wall, you can use the lens with exceeding the proper shifting amount without any problems.

When you shoot a connecting photograph, fixing your camera firmly by a tripod and the like without fail, you have to take extra care that the camera does not vary its shooting direction while an operation such as winding up the film and the like. When you shift the lens downward of the camera, the upper part of the field of view in the viewfinder becomes dark and wanes upon stopping down the aperture ring. This does not effect to the image on the film at all, so you should use a fully opened aperture upon framing and stop down before shooting. When you use the aperture stop as small as possible, it helps to increase resolution, uniformity of light amount and depth of field and to prevent internal reflection. When your subject is made of glass, plastic, or a ceramic tile emitting a harmful reflection light, it is quite effective to apply a polarizing filter in front of the lens. The attachment size is 52mm in diameter as the same as the other Nikkor Auto lenses.

Uses of PC-NIKKOR

As for the tilt-shift effect, although you may easily imagine an architectural photograph and a commercial photograph, it is rather useful to general photographs.

As for the architectural photograph, it is used for a meeting, an estimate and progress control of a constructor in addition to a document and a record of an architect. Moreover, it is used for a real estate agent and an official receiver for explaining a property and for recording a property before and after repairing. Anyway, it is effective for a subject to be shot easily. Recently, color transparency film tends to be used frequently in color photograph in proportion to frequent use of colorful new building materials, so a photograph exclusive for PC-NIKKOR can be expected.

PC-NIKKOR will become indispensable lens of a sub-camera for an architectural photographer. It will be one of memorable photographs for you to shot your house under construction.

As for a commercial photograph, not only a photograph that a commodity is just faithfully shot, but also a photograph that has a movement has recently been required for an advertisement or a brochure. To shoot the photograph with a movement, in other words, which requires a shutter chance, PC-NIKKOR has a big advantage to be able to use a viewfinder all the time.

Furthermore, as for a general photograph, PC-NIKKOR has wide applications such that it can prevent people's heads become larger upon shooting downward. When you shoot a person sitting in a Japanese-style room performing flower arrangement, if you shoot with lowering your camera position, a pillar and a shoji screen of the background become vertical, but a portion of the person's face tends to behind the flowers or the branches. In this case, if you use PC-NIKKOR, you can shoot with keeping your camera at high position with shifting the lens downward, so you can prevent this.

When you shoot upward a timetable posted high on a platform of a railroad station, it comes out to be a trapezoid and focus cannot be adjusted to whole surface. In this case also, if you shoot this by PC-NIKKOR with shifting upward, the table dose not distort and focus can be adjusted to the whole surface. Moreover, when you have to put a photograph of a machine or an article on the report of your business trip, you can obtain a correct shape of it with the help of shifting.

In a connecting photograph, it is very convenient to shoot a really wide subject that cannot be covered by a single shot. Not limiting to an architectural photograph, It can be applied to various uses such as a landscape photograph of a pleasant journey, a commemorative picture in a large banquet hall, and the like.

Swipe horizontally to view full table.

The eleventh Tales discussed a large-aperture, super telephoto lens NIKKOR-H 300mm f/2.8 made exclusively for news photographers. In the Tale Thirteen, I discuss about the Reflex-Nikkor 500mm f/8 (New) which will be more familiar to amateur photographers within super telephoto lenses.

In the Tale Seventeen, I discuss about the history of "PC (Perspective Control) NIKKOR", which has ceaselessly continued up to now and its representative model "(new) PC-Nikkor 28mm f/4".

by Haruo Sato