The Rear Dial: Optimum Configuration

G7  This is my right thumb in position to work the rear dial. I have lifted the thumb away from the camera body  a bit so you can see the relationship between the thumb and the various camera parts. The thumb support is shaped so that I can turn the dial without having to release grip on the camera with the right hand  and without needing to hitch the thumb up to get purchase on the dial.

I embarked on a study of camera ergonomics several years ago. I had found some cameras easy to use while others proved frustrating. I wanted to find out why.

I happen to have for study right now several cameras which I will use to illustrate different implementations of the rear dial. I will show that some get it right and others get it not-quite-right.

To a casual observer the rear dial treatment on each camera might appear much the same. But there are detail differences and good ergonomics always involves getting the details right.

I am trying here to illustrate an aspect of the way in which the user physically engages with a camera. This can only be fully appreciated by actually having the camera(s) in hand and working through the action sequences.  But that obviously is not possible in a blog so words and pictures must suffice. 

Let’s get right into it  starting with:

Panasonic Lumix G7

Please refer to the photo above. Previous iterations of the “Just G” Lumix cameras explored various implementations of the rear dial. 

The G5 and G6 had the dial set into the thumb support. But these cameras are quite small with a narrow control panel (the part of the camera back to the right of the monitor).

There simply was not enough space to implement this design properly. The dial had to extend around the right side of the thumb support which proved an awkward arrangement in practice. In addition the serrated teeth on the dial were too soft and rounded making the dial difficult to turn.

 The G7 has a full twin dial configuration which is optimal for a camera designed to be driven by an expert user.

Implementation of the rear dial is quite clever. The thumb support is only 2.5mm high (that is, 2.5mm above the thumb pad).  This is sufficient for a light camera. The cutaway shape of the upper part of the thumb support is critical to the operation of the rear dial. It allows the thumb to flex at the interphalangeal joint so the ball of the thumb can bear onto the rear dial and the thumb can move side to side to operate the dial without needing to shift up or down.

So although the control panel is only 30mm wide an efficient rear dial implementation has been realised.

Nikon Coolpix P900

P900  This is the hand/thumb position which gives me best purchase on the rear dial and freedom of movement to turn it. The magenta line indicates the relationship between the metacarpo-phalangeal joint and the control panel. It is 14mm higher than you see in the photo below.

P900 This is what happens if I try to work the dial by swinging  my thumb to the right. I cannot reach the dial.

This is quite a large camera due to the 83x zoom lens. At 910 grams it is not exactly lightweight either. So it needs substantial holding arrangements. These it has but the implementation could be improved.

Just concentrating on the rear dial for now please refer to the photo above.

To the casual eye the rear dial on the P900 might appear to be almost identical in configuration to that on the G7.

But there are detail differences which make for a different user experience.

The thumb support on the P900 has a height of 4.5mm above the thumb pad. This is high enough that it obstructs the thumb from moving side to side as it tries to operate the rear dial.

In order to get the thumb onto the dial and confidently rotate the dial the right hand has to release grip on the camera and shift 14mm upwards.

So what ?  Do I hear you ask ?

Well, so quite a lot as it happens. This is a single dial camera so every time you want to adjust the aperture in A or shutter speed in S you need to turn that dial. And every time you want to turn the dial you have to release the camera with the right hand, support it with the left hand, hitch up the right hand 14mm, turn the dial then release the hand again to drop it back to the start position.

So the task of turning the dial requires several actions, each complex and requires support actions from the left hand.

Note:  It is possible for me to turn the P900 dial without hitching up the right hand. In this case the thumb must be flexed at both the metacarpo-phalangeal and interphalangeal joints and the tip of the thumb brought to bear on the dial. This is possible but awkward.  The dial is more difficult to move with the tip of the thumb and I find it often requires several short mini turns to make an adjustment.

By comparison turning the G7 rear dial requires a single action by one digit with no requirement for support actions.

The P900 has a control panel 50mm wide which is plenty of space for a much more ergonomic layout of the thumb support and rear dial, such as that found on the FZ1000.

Panasonic FZ1000

FZ1000    In this case there is no need to shift grip or to flex the thumb joints. The dial is embedded in the thumb support. It is easily operated by simply swinging the thumb side to side at the carpo-metacarpal joint, an action easily accomplished without disrupting grip on the handle.

This camera has about the same width and almost as much height as the P900. Its control panel is actually slightly smaller at 45mm wide but more efficient use is made of the space available. The thumb support is 4mm high.

The wider thumb support allows the thumb to take up a more angled posture across the back of the camera. 

This is stronger and more relaxed than the more upright thumb posture required by the P900.  

The rear dial is embedded in the upper part of the thumb support, has just the right amount of exposure and nice grippy sharpish teeth.

This is the optimal location for a rear dial on a camera wide  enough to fit the dial into the support.

The thumb needs only to swing from side to side at the carpo-metacarpal joint to engage and turn the dial. 

The task of working the dial requires only one action which is simple and does not require any support actions.  The lower right corner of the camera stays in place on the ball of the thumb.

This is good ergonomics.

Silver Mockup

Mockup  This embodies some advanced ergonomic concepts such as the handle canted back 10 degrees, the JOG lever and the rear dial embedded in the thumb support in a small camera. Rear dial operation requires a single simple side to side movement of the thumb.

I made this mockup as a proof of concept for several of my ideas about ergonomics.

Quite by chance it happens to be the same width and height as the G7. The control panel is 42mm wide and the thumb support 9mm high.

The rear dial is embedded in the thumb support. This provides a rear dial operation experience similar to that of the FZ1000 but in a smaller body. The penalty for this is that the monitor has to be smaller.

It is 78mm wide while that on the G7 is 92mm wide. You can see in the photo the mockup also has a JOG lever in the top right corner of the monitor area, for super rapid shifting of the AF area.

Summary

There is a limited number of optimal ways to implement a rear dial and many suboptimal ways. This post briefly analyses some of these with reference to some actual cameras and one of my mockups.