Thumb supports

 

The camera which set the shape and style of SLR's and DSLR's to the present day was the Canon T90 of 1986. This had a prominent handle with a control dial behind the shutter button, an ergonomically practical arrangement which you will find on Canon DSLR's to this day. Turn to the rear and you will find another innovation in the form of an early type of thumb support together with an upper and lower row of buttons.

The thumb rest at the rear complements the handle on the front to make the camera secure and comfortable to hold without strain. If well designed and positioned the thumb rest also positions the thumb so it can move easily to adjacent user interface modules (UIM's).

On digital cameras the monitor takes up the lion's share of available real estate on the back squeezing the control panel into a relatively small space on the right side. Therefore the position and shape of the thumb support and the location and design of its adjacent UIM's is of critical ergonomic importance.

I identify two main types of thumb support: the angled and vertical as illustrated in the photos. My experiments with mockups and my experience using actual cameras indicates clearly that the angled type is ergonomically preferable.

This hand has adopted the half closed relaxed posture which I regard as the most effective for holding a camera. It is both strong and relaxed. Both the thumb and index finger are free to move from side to side. The index finger is also free to curl or straighten.

My concepts about the functional anatomy of camera ergonomics start with the half closed relaxed posture of the hand as shown in the photo. This is the natural position the hand adopts when relaxed. From this position the fingers and thumb can function most effectively. When I develop mockups I shape the timber until it fits in my hand with the hand in this position. The hand comes first. The camera shape has to fit the hand. When I shape a camera this way the thumb support always ends up being the angled type. This allows the hand to adopt a strong/relaxed attitude when holding the camera ready for action.

This is the hand/finger posture required to hold a camera with vertical thumb rest located at the right side of the body. This is not as relaxed or strong as the posture in the upper photo. The thumb can only move sideways to the left. The index finger's movements are restricted in both planes. The reader can confirm this by personal examination.

When a camera is fitted with a vertical type thumb support close to the right side of the body the hand is forced into a cramped/squeezing attitude. This is less effective at supporting the camera and restricts the possible movements available to both the thumb and index finger in the service of operating interface modules.

This camera has an angled thumb support, allowing adoption of the half closed relaxed hold position. The thumb is free to move from side to side in order to operate adjacent UIM's, these being the control dial on the right and AEL/AF button on the left.  The hand, wrist and forearm all adopt a natural position.

 

This camera has a vertical type thumb support. The thumb is cramped up against the base of the index finger. It can only move to the left but this camera gives it no UIM to operate if it does move that way. The rear dial is awkward to operate with either the index finger or thumb. The vertical thumb rest forces the hand to sit upright on the right side of the camera. This in turn makes the elbow drop down if the user wants to avoid having to sharply cock the wrist upwards.

 

Summary Good ergonomic design is just as easy to implement at the design and construction stage as suboptimal design. The difference to the user experience can be very substantial.