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How can to focus a view camera?

An introduction to view Camera

Focusing the view camera, has a variety of techniques, that depending on experience of photographer, can be change. The small format cameras and some medium format, essentially lens axis is perpendicular to the film surface. The other hand, junction of the lens (lens mount) is parallel to the film surface. So the only way to Focusing the subject in these cameras is lens focus ring. Also aperture ring must be used to control the depth of field. However, use a small aperture, creates other problems such as diffraction phenomenon. So to get maximum depth of field, the camera lens should be set at a hyperfocal distance.

In the large format camera due to ability to movement of lens mount (front standard) and film surface (rear standard), regardless of the size of the aperture, can be increased depth of field. But usually due to increased image quality, in addition to movement, must be used a small aperture.

In the view camera, optical axis and the focal surface of lens (surface that is perpendicular to the optical axis of the lens, or lens mount), can be change relative to axis and surface of the film. One of the most important changes that are considered in this section, is creating a angle between the focal surface of the lens to the film surface. This rotation can be relative to the horizontal axis (Tilt) or vertical axis (Swing).

If the subject was located on a horizontal surface, such as a view of the plains and mountains in distant, Tilt will apply. And if the subject was located on the vertical surface, such as, a subject who is a rock wall, Swing will be used. In some situations, both methods should be used. However, to better understand the above, i will explain a bit about the view Camera.


The view Camera

Principally, large format cameras or view cameras, are built to many species. But the most traditional is the monorail and flatbed cameras.

Monorail view Camera

In the monorail, there are two parts, front (lens) and rear (film holder) that are attached to a horizontal rail. The front part of camera, that lens is attached to it, called the front standard and the rear section, that film is put to it, is called rear standard. These two parts are attached to each other by the accordion-like cover, which is called the bellow. Bellow, in addition to preventing the penetration of light into the camera, provides flexibility needed to movement front and rear standard. By moving front and or rear standard, you can to focus the camera.

In the some cameras, front and rear standard will rotate, around a horizontal axis, which is passing the optical axis of the lens. This type of rotation is called Axial Tilt. In the other types of cameras, front and rear standard will rotate, around near the bottom, or about one-third lower optical axis of the lens. This type of rotation is called Base Tilt. Thus, rotation front or rear standard, to up or down, while the camera rail is horizontal, called Tilt. But if the front and rear standard to rotate around the vertical axis, which is called Swing. Also both front and rear standards can movement horizontally to the left and right, this move is called the shift. And the vertical movement, the front and rear standard, to up or down, is called Rise/Fall.

Basic view camera terminology
Basic view camera terminology
Lens axial tilt theoretically
Lens axial tilt
Lens base tilt theoretically
lens base tilt
Lens swing theoretically
Lens swing
Linhof M679 monorail camera
Linhof M679 monorail camera

Flatbed camera

The flatbed camera, front and rear standard, attached to the bottom plate of the camera. Bottom plate of the camera, have hinges to close the camera. So after closing the camera, the set is small and portable. Of course, this feature will limit some camera movements. In some cameras, front and rear standard, have a Base Tilt. The Shift and Rise/Fall movement is in the rear standard limited or not possible. So the flatbed camera some movements is sacrificed for portability. Nevertheless, movements in flatbed camera enough to completely focus on the subject, and easy portability, makes the suitable camera for a landscape photographer.

Toyo-Field 45A flatbed camera
Toyo Field 45A flatbed camera
Toyo-Field 45A flatbed camera open-close system
Toyo Field 45A open/close system
Toyo-Field 45A flatbed camera lens plane vertical shift
Toyo Field 45A lens plane vertical shift
Toyo-Field 45A flatbed camera lens plane lateral shift
Toyo Field 45A lens plane lateral shift
Toyo-Field 45A flatbed camera lens plane swing
Toyo Field 45A lens plane swing
Toyo-Field 45A flatbed camera lens base plane tilt
Toyo Field 45A lens base plane tilt
Toyo-Field 45A flatbed camera film base plane tilt
Toyo Field 45A film base plane tilt
Toyo-Field 45A flatbed camera film plane swing
Toyo Field 45A film plane swing

Basically, large format cameras (View Camera), have a high weight and size. So use a tripod is necessary for them. This issue causes the photographer, perform more attention on the subject and techniques.


View camera focusing methods

There are three ways to set the View Camera:

First method:
This instructions are very visually and depends on the experience of the photographer. In this method, the evaluation of the subject performed with the eyes on the groundglass. So performed with most of the view camera and no need special accessories. This method is quite approximate, but has a repeatability (a real adjust tilt and swing). Many photographers do these instruction based on their experience in different ways.

Second method:
In this method should have a metric scale, so that to be installed on camera rail or base. By This method, rather than to guess the focus area, we measured the best area.

Third method:
The law median, in this method, the camera will focus on the midsection of foreground and background of the subject.


Principles focusing

The Scheimpflug rule:

We all know that when a conventional camera without movement is used, such as 35 mm or medium format, all objects that are at a vertical distance from the plane of the film, simultaneously can be focus. For a rigid camera, such as 35 mm, the lens plane and the film plane are parallel (or at infinity are parallel). So, subject plane must also be parallel to the two planes. But in a view camera, the geometry relationship the plane of lens (front standard) and film plane (rear standard) are adjustable. This feature makes it almost impossible to focus on any level of the subject, even receding surfaces, or slanted.

The Scheimpflug rule says, If hypothetical lines from, the film plane, the lens plane (the lens plane that is perpendicular to the optical axis) and subject plane (the plane of subject that should be focus) to cut each other at one point, the depth of field will be maximum.

The Scheimpflug rule theoretically
The scheimpflug rule theoretically

To use the scheimpflug rule, several issues must be considered:

— This law helps to you identify external figure camera movement. For example, if you adjust your camera back vertical, and you want to focus on the ground surface, you must tilt the lens. Moreover, by visualizing the intersection of back surface the camera and the ground surface, you will be able to estimate the required limits lens tilt. For example, if you use the camera near to the ground surface, tilt will have more. Also, if you use a lens with a longer focal length, is needed more tilt.

— In cameras advertisement, camera tilt 45 degrees will be announced. But except for macro photography work, small amounts of 5 to 10° tilt is enough.

Depth of field surface is equal to the volume surrounding the subject. When we use the Tilt or Swing, this volume is not constant and depends on the distance to the camera. In closer to the camera, this volume is smaller. This volume can be visualized into a cone shape. When you're focused on the surface of the earth, the top of flowers are close to the camera may be out of focus, in case the top of mountain, will be quite obvious.

— When you get focus on a particular surface of the subject, the camera can take many forms. As the figure above, the point of intersection of imaginary line front and rear standard, with subject surface can be numerous.

— To determine the intersection point this lines is not so easy to establish the scheimpflug rule.


Which standard should be Tilt?

Most cameras have a Tilt and Swing movements in front and rear their. Esthetic considerations, will determine, Tilt and Swing in front and rear standard.

Front standard Tilt, keeps the linear structure of vertical subject.

Film plane tilt, shows the foreground, "outstanding" and larger, and in fact the near–far more impressive and will look dreamy. However, disrupts the structure of the vertical lines. And they do not appear as parallel lines. So if there are vertical lines on the subject (such as tall buildings), try avoid using the film plane tilt.

Front standard Tilt will need, greater image circle of lens than the rear standard Tilt. So, if your image circle of lens is small, the front standard Tilt to do more carefully.

Front standard Tilt, deflecting optical axis of the lens from the film center. Thus, during exposure, to the edge of the film (in this case top of film) gets underexpose.


Axial Tilt or Base Tilt ?

Usually, flatbed camera, equipped with Base Tilt and monorails, the Axial Tilt. Some cameras have both, that's a big advantage. However, this is a personal tastes and does not affect image quality.

— In Base Tilt, out-of-focus areas, is more visible. Also, if the farthest point of subject, not near the axis of Tilt, Base Tilt would be confusing.

— During the simultaneous use of Base Tilt and wide angle lens, two front and rear standard, can not be sufficiently close together.

Axial Tilt, relative to Base Tilt is less need to re-focus and re-compose.


To focus on the subject, which will move the standard, front or rear?

— In close up work, focusing with rear standard, relative to front standard keeping the magnification.

— For landscape photography, focusing will be the same for both methods, but i prefer to focusing with front standard.

 

A Note about the small format camera TS lenses

TS lenses available in Canon and Nikon cameras, do not performance Tilt and Shift method in a large format camera. In return rotating the lens will determine the Tilt axis. When the rotation axis is in the horizontal position, similar to a view camera, you'll Tilt. And when rotation axis is in vertical position, you will use the Swing. Generally, only once you set the plane of focus on the space, and then Tilt axis, is determined by the intersection of this plane with the surface plane. However, this methods is somewhat difficult in a small frame a 35 mm camera.


Describing practical method focusing in view Camera

The first method of adjusting the view camera:

This part is quite experimental, and should be done by trial and error.

When the subject is essentially flat, like a flat pond or lake, flat landscape with mountains in the distant, plane subject is clearly understood, and wide aperture will be used specifically. The problem starts when the subject is somewhat three-dimensional. For example, imagine there is a view contains a large rock foreground distance of one meter, and a great mountain at 1,000 meters. Which side of rock, or what part of the mountain, we focus? In this case there is an answer, If you create the scheimpflug rule, the depth of the subject, twice the distance from the point of focus will be in front of the camera. This is a similar case, the subject is parallel to the film surface.

If the camera is focused on top of the foreground rock, the focus is defined between two points. The first point, will be about two-thirds the distance to the top of the rock, and the second, two thirds of the distance to the top of the mountain. If there is one a tree in the distance, it will not be easy solution. And if you do not use the movement, should be much as possible to the close the aperture.

If you can not get a good plane focus, it will be because the subject is inherently three-dimensional. (eg a landscape with tall trees in the foreground) so, you should not use the Tilt and Swing. In this case, you will have a minimum depth of field level. The only way to get enough depth of field, is closing the aperture as small format camera. Sometimes it may be necessary to close the aperture strongly. Some compositions may not be focusing sharp entirely with the view camera. You must learn to find different compositions.

Adjust the tilt and/or swing and focus

— If plane of subject is horizontal, like most landscape photography modes, which should be obvious foreground and background, should only be used of the Tilt.

— If plane of subject is vertical, it should only be used Swing.

— Otherwise, you must use both. Do not adjust both simultaneously, but proceed sequentially. If at first you do Swing, you should check the Tilt, and the left and right parts of the subject, check the horizontal line. Conversely, if the Tilt was performed, you should check the Swing, and the upper and lower parts of the subject, check the vertical line.

To adjust Tilt, high/low, and to adjust Swing, please use of the left/right, front or rear to standards.

Procedure:

1- Please choose a near point (top of groundglass) also, select a point distant (center/bottom of groundglass), In this example the mountain/rock, nearest point, about two-thirds the height of rock, and farthest point is located about two-thirds of the height of the mountain. If you use of the Axisl Tilt, farthest point should be near the middle of groundglass.

2- Please focusing the camera on, the farthest point from the subject.

3- Then the focusing nearest point by using Tilt. You should add Tilt. Image composition is determined according Tilt applied (unless Axial Tilt, to be used). May need a little lift of the lens for proper composition (Rise).

4- Now, the evaluation will focus on the farthest point and if necessary re-focus. So go back to step 1. Otherwise, the work is finished. Usually a series try and error is required. In this guide, you should increase Tilt frequently, and then check the focus. If, more Tilt to do, you must repeat the steps more focus.

Some people prefer to focus on the nearest point, then perform Tilt, the farthest point. It is suitable for Axial Tilt. In case the above mentioned method is suitable for base Tilt. Everyone should be himself​​ tested, and choose the most appropriate method.

My method for planar subject, is focusing on a farthest point, and Tilt on the nearest point. Which subsequently brought down the front standard (fall), and would also control the amount of light in the center of the film.


The second method of adjusting the view camera:

In this method, a scale in millimeters similar to ruler, should be installed on the camera. So that distance between farthest and nearest points, be measured on camera. More monorails have these scale, but some of the flatbed, it must be installed. The line marking, will help you for reading. Method is very simple. By trial and error, determine the minimum Tilt, for the focus. Then with calculation will be determine the best focus point.

Toyo-Field 45A flatbed camera roller for focusing
Toyo Field 45A roller

First, you must learn not using the above method. Suppose, we have a view of some tall tree in the foreground. In this case, the subject would not be planar. So, either you can use a small aperture, or movement method of the camera.

— In the first case, the focus will be on back of the trees, and trees and the horizon will be out of focus. So, you should to use a small aperture.

— In the second case, if you do Tilt the lens, the focus is somewhere around 2/3 the height of the tree. So the bottom and top of the tree, will be out of focus, and you must re-use of a small aperture. Which two methods is more appropriate? By using of measuring Focus, near and far points, the answer is achieved.

Procedure:

Tilt Precise adjustment:

Suppose the subject include a rock, at a distance of 1 to 2 meters, and the mountain is 1000 meters away from camera. Perform the following steps respectively:

1– Recording the focus before the Tilt

1–1– Focus on nearest point of the subject (rock, in the highest point of groundglass). Record it A1, and note it's value, in the millimeter scale.This size is equal to the maximum extension bellow.

1–2– Focus on farthest point of the subject (mountain, in the lowest point of groundglass). Record it B1, and note it's value, in the millimeter scale. This size is equal to the minimum extension bellow.

1–3– Calculate the difference between A1 and B1, which is equivalent to D1.

1–4– The amount that you think is necessary, guess the Tilt, and run it.

2 – Recording the focus, after the Tilt

After the steps 1–4, again do the following steps:

2–1– Focus on nearest point of the subject (rock, in the highest point of groundglass). Record it A2, and note it's value, in the millimeter scale.This size is equal to the maximum extension bellow.

2–2– Focus on farthest point of the subject (mountain, in the lowest point of groundglass). Record it B2, and note it's value, in the millimeter scale. This size is equal to the minimum extension bellow. In this example, mountain/rock, is near and far points of subject.

2–3– Now, get the difference between A2 and B2, which would be equivalent to D2.

Method to calculate the exact size of the Tilt

— If D2, to be smaller than D1, increase the Tilt and repeat from step (2) again.

— If D2 to be larger than D1, reduce the Tilt and repeat from step (2) again.

— If D1 and D2 was equal, Tilt is correct. And focusing completely done.

 

The third method of adjusting the view camera:

Fine tuning the focus point by using the mediocrity rule

This method regardless of the movement, is used to focusing the view camera:

1– Focus on the nearest point (top of groundglass). In this example of the mountain/rock, over would be rock. On the ruler, named point A, please recorded.

2– Focus on the farthest point (bottom of groundglass). In this example of the mountain/rock, down would be rock. On the ruler, named point B, please recorded.

3– Determine the middle point A and B, it is called C, And set the camera there. In this case, nearest And farthest point is equally focusing.
This is regardless of format, lens and movement. When you focusing on the point C, the following relationship is established:

(C-A) = (1+MB)
(C-B) (1+MA)

MA is magnification of nearest point, and MB is magnification of farthest point. This point is always closer to the A up to B. Sometimes the mediocrity rule is not good method. And that is when, to be a significant difference between two magnification. For example, when you want, with a very wide angle lens to take close-up images.

If you encounter the following conditions do not use the mediocrity rule:

— The furthest point to be horizon, do not use the mediocrity rule. So, if you do movement, you are in this mode.

— If you have a parallel lines in the distant horizon, focusing should be, closer to the infinite, up to the foreground.(focusing on two-thirds of the distance between A and B, can be used effectively to determine the F-stop). In this manner, sharp focusing more, is considered to foreground. Ansel Adams recommended, if supposed to be sacrificing sharpness is better not to foreground.

Refrences:
view camera by Wikipedia
How to focus the view camera by Q.-Tuan Luong
The Camera by Ansel Adams

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