Operating Systems

CAMERA ERGONOMICS

Part 10   Operating Systems

Author  AndrewS




Photo 1 Control dial Index finger 1

Users and cameras      In ergonomic terms there are two main groups of camera users, snapshooters and controllers. This has led to the development of two main camera types. For snapshooters there are cameras with a simplified user interface and no eye level viewfinder. For controllers there is a range of cameras with a more fully featured user interface including an eye level viewfinder.  Snapshooters can readily use fully featured cameras by selecting one of the fully automatic modes, thereby disabling many of the hard control modules and perhaps electing not to use the eye level viewfinder.  

This discussion of operating systems assumes a camera designed for full user control of all functions.  It has both monitor and eye level viewfinder and a full complement of interface modules,  allowing a high level of communication with and control of the photographic process.

Historical note       For most of the history of photography cameras have been controlled by mechanical connections between the operator and the device. This constraint limited the options available to designers. The emergence of electronic operation has brought greater design freedom but also much more complexity. Paradoxically, the electronic era has made the camera designer's task more difficult. The freedom to make a camera any shape at all, to use any kind of interface technology and to locate control modules anywhere on or off the camera forces the designer to make decisions about all these things.

Communication   Communication is a two way street.  The camera needs to clearly present status information to the user. The user must communicate his or her instructions to the camera quickly. Mechanical rangefinder and SLR cameras of the mid twentieth century era managed this task quite well. Lens aperture, focussed distance and depth of field were directly visible on the lens barrel. Shutter speed was displayed on a top dial, as was film speed.  A camera like this gave the operator a direct readout of and direct control of current settings for primary exposure and focussing variables.  

For the photographer willing to practice the skills required, a camera like this provided a very satisfying user experience and good photographs too.

Electronic cameras in the early part of the twenty first century present the operator with a hundred times as much information. They also demand a hundred times as many responses from the user with decisions about settings and image capture options.

The electronic revolution which some hoped would simplify camera operation has had the opposite effect.

Configuration   In the days of mechanical connections every button or dial always did the same thing.  On an electronic device every user interface module can be programmed to carry out any task of which the device is capable.    Camera designers need to use this capability so a user can programme the camera to operate the way that particular individual wishes. When a camera offers 500 or more options for various combinations of settings affecting every aspect of operation it is essential that the user be able to consign the majority of these to a menu and assign direct access only to those required for immediate use in the capture phase of operation. Each user will have a different idea about which items require direct access and that will change with time and experience.

My view after using many cameras over a 60 year period is that camera manufacturers in the early part of the twenty first century have been extraordinarily slow to understand the  importance of communication and configuration.

Example   Examples abound but here is one just to make the point.  In a major corporate initiative, a well known camera maker [Nikon] introduced a totally new model with a new lens mount [Nikon 1, CX]. The camera has something which looks like a main mode dial, located where it is easy to see, operate and by the way, bump accidentally. One of the options on that dial is called "Motion Snapshot". This makes a short, high speed video and  takes a still photo. On playback you get a slow motion version of the video, the still photo and  music. The same camera buries the main shooting mode and ISO in a menu. Some people might think that Motion Snapshot mode is a great idea, at least until the novelty wears off.  But then they are stuck with the manufacturer's preset dial/button function allocations which may not suit at all.  

A better approach would have been to add more items to the shooting mode dial  and allow the user to select functions allocated to the dial as well as the various buttons.

Generic user / device interface options   What kinds of generic systems  might allow the camera and user a two way exchange of data and  control ?

Voice activation  The technology exists now (2012) for cameras and users to communicate by voice. The idea may seem attractive but I have not seen any reports of actual use. One potential disadvantage of  this method is neurophysiological. It is usually faster to do something than to utter a voice command for the same thing. The reason for this is that translating a thought into words is a complex task. The thought has to be transferred to the appropriate part of the cerebral cortex, coded into words, transferred to another part of the cortex then onwards to the voice muscles.  Simply doing the thing avoids the neurophysiological data processing required to express the thought in words.

Imagine trying to steer a car by voice command.  "....turn left now car.........no, no, that's too far, come back a bit..........oops..........crash.

Eye control   Some years ago Canon developed a system by which the user could look at the part of the image required to be in focus and by so doing move the active autofocus area. This actually worked, well it worked for me anyway, but perhaps not for others because the feature did not last long in Canon's lineup.

Touch screens   The electronic corporations which make camera monitors also make touch screen devices such as smart phones and multifunction tablets. It is no surprise therefore that touch screen controls have found their way into cameras. But a camera works in a  fundamentally different way from a multifunction tablet. The user looks at the subject through the camera and operates the controls preferably without having to look at them. In this respect using a camera is more like driving a car than operating a multifunction tablet.

A touch screen is  inaccessible when an eye level viewfinder is in use. Even when using monitor view, operating controls on a touch screen poses difficulties.  The user has to remove one or the other hand from holding the camera in order to reach the screen which means the camera is no longer being held steady. Then putting fingers over the screen makes it difficult to see the subject.  And, of course you get finger grease all over the screen.

Touch screen operation might be quite feasible for a camera supported on a tripod.

Interface modules (IM)   Voice activation, eye control and touch screens sound promising but in real world use hard physical controls prove to be the most suitable for camera operation. By this I mean discrete things on which hands and fingers are laid.   These include buttons, dials, sliders, levers, lens collars, rings and JOG type devices.

As a group I call these interface modules. My apologies for this bureaucratese sounding terminology but the words do express my meaning.

There are several types of  IM. These include

* Set and See   The set and see module can be a dial, lever, slider, ring or collar. It has clearly visible markings so the user can see the current setting at a glance. Shooting Mode, Drive Mode, ISO, Shutter Speed and Exposure Compensation are typical parameters assigned to a set and see module.  IM's of this type have the virtues of direct readout  and direct user control. They are not usually visible with the eye level viewfinder in use.  However some can be readily adjusted by feel while looking through the eye level viewfinder with the set value duplicated in the viewfinder. So most are best used for adjustments in the Prepare Phase of operation but some can be used effectively in Capture Phase.

* Single function, preset   Many cameras use modules of this type. If I had any say in camera design I would abolish these completely. In my view there is no excuse in the electronic era for modules having a single function determined by the manufacturer.

* Single function, user assignable  These are slowly becoming more popular, but should be universal. More, it should be possible for the user to assign to any module any function from a complete menu of all possible functions. Electronic cameras offer such a plethora of selectable functions it is not remotely possible for the maker to guess which ones any specific individual user will want to have at his or her fingertips.  Furthermore many users will want to change their module function assignments after experience with the camera.

* Mode dependent function, preset  The task performed by one of these modules depends on the camera mode in play. The classic example is a main control dial. In Setup Phase, when working through menus, the control dial can scroll through submenus. If a Quick Menu is used in Prepare Phase, the control dial can navigate from one item to the next. In Shooting mode it will alter aperture in A, shutter speed in S, program shift in P and either shutter speed or aperture in M. In Review Phase  the main dial can scroll through images or perform other functions.

JOG Lever   Another example of mode dependent function could be a JOG type lever. This is a lever which can be pushed up/down/left/right in any direction and pushed inwards as well, for added functional capability. A well designed and positioned JOG lever is a great asset to an electronic camera. In all Phases of use there are equirements for an interface system to move something up/down/left/right. One way to achieve this is to press a button to start a process, then use a four way controller then press an OK or similar button to confirm the change. The JOG lever can eliminate most of this fiddling by directly controlling position at a touch.

Such a module can be used to navigate around a menu screen in Setup  or Prepare Phase.  It can provide size change (with one or two inward pushes) or lateral movement of AF position in Capture Phase,  enlarge then explore an image in Review Phase or start recording in Movie Mode.

* Mode dependent function, user assignable     The utility of mode dependent modules is increased if user assigned options are available.  For instance in P mode the dial could activate program shift or exposure compensation.

Juggling   This is something buskers do in the town square. Unfortunately many cameras require their users to do the same thing when attempting to operate the device. Too many cameras require the user to drop the unit down from the eye to make an adjustment. Too many demand that the user juggle the camera between right and left hand, changing grip with each in order to make adjustments to primary and secondary capture parameters.  In the electronic era there is simply no excuse for this.

Photo 2 Control Dial Index Finger 2

Unlabelled control dials, How many and where ?   Some cameras have no unlabelled mode dependent  control dials, some have three or more. Some cameras place one or more dials on top of the camera, some on the back. Some place these dials so they are operated by the right index finger, some by the thumb, some by both. There is obviously no general agreement about this matter at all. Contrast this with motor vehicles. Climb into almost any vehicle and you will find the major steer, go and stop interface modules are the same type in the same place.

Is it possible to identify an optimum arrangement of  camera interface modules, based on ergonomic principles, separate from any consideration of style, fashion, custom, or preference ? I believe the answer to that question is yes.

In Part 6 of this series I discussed hands and fingers. The ergonomic studies behind this discussion showed that in the case of a standard, generic, hand held camera of modern design the only body part not involved in holding and/or supporting the camera is the right index finger. It therefore follows that the right index finger is the best human asset for operating a shutter button and a main control dial.   

I have read opinions from some camera reviewers giving preference to a thumb operated control dial. The basis for this is usually a view that the index finger should be free to operate the shutter button. However my time and motion studies of camera operation show the index finger never has to operate a control dial and the shutter button at the same time. You never want to change, say, the lens aperture and depress the shutter button simultaneously.  A further problem is that in order to operate a control dial with the right thumb it is necessary to partly or completely release the right hand, thus destabilising the camera. A recent (February 2012) camera release [Sony NEX7] has no main mode dial, no control dial operated by the right index finger and no JOG lever. But it does have three unlabelled control dials each operated by the right thumb.  This system generates a lot of complaint on user forums about inadvertent activation of those rear dials. My concern about this system of user interface modules is more fundamental. My time and motion analysis of camera operation would suggest that the designers of this "three dial" approach have failed to grasp the fundamentals of ergonomics at a very basic hands and fingers level.

It is a general principle of functional design that a human machine interface will provide optimal control when it is provided with just enough interface modules (controls) to get the job done but no more.  My research with mockups, using the principle of  "form follows fingers" leads me to the view that the following basic arrangement of control modules will provide an effective human machine interface with minimal clutter and a very low rate of inadvertent module activation.

1. A "set and see"  Main Mode Dial with maker and user defined functions, and  a "set and see" Drive Mode dial or lever with maker and user defined functions. These two dials, located on the camera top,  provide instant visual feedback on major operating parameters which require adjustment in the Prepare Phase.

2. User configurable buttons with default functions for other parameters requiring adjustment in the Prepare Phase.  These would include AF Mode, Metering Mode,  Macro Setting,  White Balance, Quick Menu, Display options, Flash options,  and others by user allocation.

3. A JOG type lever immediately accessible to the right thumb without shifting grip with the right hand.  This needs  a comprehensive set of maker and user defined functions. This provides direct access to a range of functions in the Capture Phase and also Prepare and Review Phases.

4. One unlabelled main mode dial, operated by the right index finger and located immediately in front of or behind the shutter button,  provided that the dial is positioned and angled to match the natural movement of the index finger.

5. A cluster of four modules operated by the right index finger. These are Shutter Button, Main Mode Dial, ISO and Exposure Compensation, with some user configuration.

In Part 12 of this series I will show how this works on mockups.

Photographs 

Photo 1, Control Dial Index Finger 1   This camera has generally decent  ergonomics but the top area shown here could be improved. The main control dial is operated by the right index finger which is desirable. However the distance between the centre of the shutter button and the dial is 16 mm which is more than necessary for clearance between the two. The dial is parallel to the camera back which might look tidy but is suboptimal ergonomic practice as the finger which operates the dial falls across the upper part of the camera at an angle. Now see the ISO button behind the control dial. This is a further 12 mm back from the dial making a total distance of 28 mm from the shutter button to the ISO button. This is at or beyond the limit of side to side movement of the metacarpophalangeal joint for many people. Therefore those people will have to shift grip with the right hand to access the ISO button.  In addition the ISO button is one of four in a row, each the same size, with ISO only identified by a tiny little braille like nipple on top.

The rule with ergonomics should be "form follows fingers". This camera gets half way there but could easily have been much better.

Photo 2, Control Dial Index Finger 2  This is a substantially more compact camera but with the same basic relationship between the shutter button and the main control dial. The distance between them is 12 mm.  This is only 4 mm less than the distance in Photo 1, but it makes shifting from one to the other significantly easier. The index finger in the photo is lifted up so you can see both control modules. Again the control dial is neatly lined up parallel to the monitor even though it would better fit the finger which operates it if it were to be angled about 25 degrees.

Photo 3 Control Dial Thumb

Photo 3, Control Dial Thumb   This demonstrates what can happen when several ergonomic errors co exist. The main control dial is thumb actuated and the dial itself is almost fully submerged in the surrounding material. In consequence the only way to reliably operate the dial is to hold the thumb as shown here so the very tip of the digit, just below the fingernail, is the body part bearing on the dial. This forces the base of the thumb away from the camera and  breaks the opposition posture required to get a proper grip on the device. In addition a forceful push with the thumb is required to operate the dial so the index finger has to be removed from the shutter button and re positioned in front of the camera to resist the thumb pushing from the back.  This camera is the same size as the one in Photo 2, indicating the problems are due to poor ergonomic design and are not simply due to the small size of the camera. In this photo only the left hand and the middle finger of the right hand are preventing the camera from falling on the floor.

Photo 4 Back Button AF Start Good

Photo 4, Back Button AF Start Good    Back button AF start is desirable especially when following action as it separates AF activation from metering and capture.   This is the same camera as in Photo 1. The AF start button is obscured by the thumb. To activate AF the thumb has only to flex a few millimeters at the interphalangeal joint. Full grip on the camera is retained.

Photo 5, Back Button AF Start Bad   On this camera the AEL/AFL button can be configured to activate AF start/lock, which is desirable. However the button is incorrectly positioned.  The button is set forward of the plane of the monitor which prevents the unflexed thumb from reaching it at all.  In order to bring the thumb to bear on the button it has to be  flexed at the interphalangeal and metacarpo phalangeal joints. You can see in the photo this forces the base of the thumb and the palm of the right hand away from the camera, completely disrupting the grip.

Photo 5 Back Button AF Start Bad

This same camera has the main control dial located on the handle in front of and below the shutter button where it is covered by the middle finger as it grips the handle. The only way to access the control dial with the right index finger is by completely shifting grip with the right hand.     Note that this camera does have a well designed and located Main Mode Dial and Drive Mode  lever.

Photo 6 ISO Button Placement 

 

Photo 6, ISO Button placement   This is a 2012 professional camera release by a manufacturer with 76 years experience at making cameras. You can see the ISO button is on the top left of the camera. To change ISO the user has to drop the camera down from the eye, release the left hand from the lens, locate the ISO button by looking at it (the design makes it almost impossible for ordinary mortals to find it by touch) push the button with a finger of the left hand, return the left hand to the lens then scroll to the required ISO with the right thumb or index finger on the front or rear control dial. It would have been so easy to configure the red dot button behind the shutter button to activate ISO. Then the operator could control all the primary and secondary exposure parameters with the right index finger while looking through the viewfinder.