This
post is about Mode
Dependent Control Dials. These are dials without inscription. Their
function depends on the currently set capture mode. I will call them Control Dials in this post.
In Capture Phase of use they are second only to the
shutter button in the hierarchy of UIMs (User Interface Modules). Therefore all
aspects of their design are of the utmost importance to camera operation.
They change primary exposure parameters in Capture Phase and
can be used for scrolling in Setup and Review phases.
They are distinguished from Set and See dials which
are inscribed with various settings. The function of set and see dials is always the same and the current setting can be
seen by looking at the outside of the camera (you don’t have to look in the
viewfinder or at the monitor). Their settings can be seen even if the camera is
switched off.
Set
and see dials are most useful for Prepare Phase actions,
especially changing main capture mode, focus mode and drive mode.
Traditional-vs-Modern
Control Systems
This post refers to modern control systems based on the [Mode
Dial + Control Dial(s)]
configuration. Several modern
cameras use some variant or hybrid of the traditional system based on the [Aperture
Ring + Shutter Speed Dial + Exposure Compensation Dial] configuration.
I have extensively analysed, compared and reported elsewhere on this blog the
ergonomic effectiveness of the two systems and concluded that a well
implemented modern system (many are not well implemented) is decisively
superior.
Haptics This post is mostly about the location and
configuration of control dials but that is not to neglect the huge importance
of haptic issues in dial design. Control dials need to be easy for the
operating finger(s) to reach and operate
yet not be subject to unwanted operation, for instance by being bumped while
carrying out some other action.
Serrations on the dials need to be sharpish and
‘grippy’ for the operating finger(s).
Dials need to stand proud from the adjacent body sufficient
for easy operation without excessive risk of inadvertent movement.
The required amount of turning force on the dial needs
to be carefully calibrated to the finger(s) which are intended to operate it.
I have owned and used cameras the dial(s) of which
were so difficult to operate that I had to wonder if the maker had ever tried a
working mockup prior to production.
Worst was the Panasonic G3, the rear dial of which was almost completely
buried in the body. To operate the dial the user had to pull the right hand
away from the body of the camera, sharply flex the thumb so as to apply the tip
of the thumb just below the nail onto the dial in order to turn it. It was nigh
on unusable.
The good news is that Panasonic’s designers are learning.
The GH3/4 and FZ1000 have excellent rear dials.
The
left hand and fingers There are eight ways by which the left hand
and fingers might interact with the camera/lens. These are defined by
* Eye level vs monitor viewing
* Landscape vs portrait orientation
* Over lens vs under lens left hand position
(2x2x2=8)
This means the left hand/fingers could come in contact
with and interact with the lens anywhere around its circumference.
In consequence left hand controls for Capture Phase
operation must be circumferential rings around the lens with lands or
serrations all the way around.
It is not feasible for the left hand to operate control
dials in Capture Phase. It can operate
various levers, switches, buttons etc on the body or lens in Prepare Phase when
the user can drop the camera down from the eye.
On the other hand (literally) the right
hand/fingers are, or optimally should be,
always in the same place in relation to the camera parts.
Therefore I have and most camera makers also have
allocated control dials to operation by the index finger and thumb of the right
hand.
Throughout
this discourse I
assume the camera will have an ‘Auto’ mode for snapshooters who do not care to be bothered by all this business
of control dials.
A
study of functional anatomy
forms the basis of my work on control dials and their operation.
The
right index finger is
the only one of the ten fingers which has exclusively operator duties with no
gripper duty. Starting from the optimal
‘half closed relaxed’ position of the hand/fingers, it can flex by movement of
the interphalangeal joints about 30mm and can move side to side at the
metacarpo-phalangeal joint about 20mm.
Obviously the
actual amount of possible movement depends on the flexibility of each
individual’s joints and the presence of arthritis or other sources of
restricted movement. But the figures
given above are a working guide for design considerations.
The
right thumb has
to undertake both gripper and operator duties.
The primary gripper function of the thumb is achieved
by a movement called ‘opposition’. This allows the tip of the thumb to touch
the ends of each of the other fingers and is enabled by rotation at the carpo-metacarpal
joint. Opposition allows humans to hold
a camera and of course, many other things.
Without unduly disrupting opposition the thumb can,
while continuing to hold the camera, move side to side, about 25mm each way, at
the metacarpo-phalangeal joint and can flex at the interphalangeal joint.
These
possible movements of the index finger and thumb have guided my search for the optimal
location and configuration of control dials.
If
you look at the actual
positions of front and rear control dials on various cameras you might be
excused for thinking that ‘anything goes’, with dials scattered about like
confetti at a wedding.
The fact that users manage to make some of these
creations work is a testament to human dexterity not laissez-faire design. In many cases users make cameras work
despite bad design, not because of good design.
In the case of a single
dial camera should the dial be
located in front, for the index finger to operate, or at the rear, for the
thumb to operate ? Perusal of existing
cameras reveals there is no industry consensus about this at all.
Even within the model line up of most manufacturers, there is no consistent
approach.
Yet the answer is perfectly obvious when the question
is analysed ergonomically.
The index finger is the only one without gripper duty
and it has the greatest range of free movement provided an optimal handle design is utilised,
as described in my previous post.
So
a single control dial is optimally located for operation by the index finger.
Note:
Some commentators, bloggers and respondents
to my posts and apparently some manufacturers (based on their actual products)
take the view that the thumb should optimally operate the control dial while
the index finger is poised over the shutter button ready to capture the
picture.
But that is brain logic.
Ergonomics requires finger logic which says that
shutter button and the control dial always operate sequentially, never
simultaneously. So if they are located
close together (not too close) and correctly designed we have the ideal
configuration.
Next question: Is
there a ‘best’ position and if so where
?
Review of actual cameras shows control dials in three
main locations in relation to the shutter button:
1. In front of, high/low
2. Concentric with
3. Behind, near/far
Please refer to the photos for examples of these
dispositions.
Guiding
principles
1. The right hand and fingers should be most
comfortable and relaxed in the position in which they spend most time in
Capture Phase. That is with the index finger on the shutter button. When I make mockups I put the shutter button
where my index finger wants to find it then figure out optimum positions for the adjacent control modules.
Look at the pictures of Mockup #13. That shows where
my fingers told me the shutter button needs to go after I shaped the handle for
comfort and secure grip. Then I added
the control dial and adjacent two buttons,
guided at each step by my fingers.
2. The control dial should be positioned close enough
to the shutter button that it can easily and reliably be located and operated
by the index finger by feel, without any need to look at the controls.
After much experiment I have settled on a horizontal
distance of 12mm between the center of the shutter button and the center of the
control dial. This to some extent depends on the width of the shutter button
but 12mm is in the optimum range. Any less is likely to be insufficient for
functional separation. Any more is just forcing un-necessary side to side
movement of the index finger.
Many cameras utilise excessive separation between the
shutter button and control dial which serves no useful purpose but demands an
uncomfortable amount of lateral movement which may for many users only be
accomplished by shifting grip completely with the right hand.
3. The top surface of the shutter button and the
control dial should both be at the same height relative to the natural movement of the index finger. This does not
mean relative to the ground or any other fixed reference. It means that the
index finger travels across an inclined plane as it moves from the shutter
button to the control dial and that inclined plane is the height reference.
Sports car drivers will understand this. They want the
accelerator, brake and clutch pedals at the same height so moving from one to
the other is fast and reliable.
4. The control dial should be positioned and aligned
on an axis so that flexion of the interphalangeal joints of the index finger
bears directly on the dial. See the
photos for further reference.
5. The upper surfaces of both the shutter button and
control dial should be quite large and strongly textured (each very
differently) so they are easy to locate and operate by feel.
Bring
all this together and what do we get ?
Basically, mockup #13.
The shutter button is located forward just where it wants to be. The control dial is close, but not too close,
behind. In addition this configuration
of shutter button and control dial on top of an inverted L style handle enables
the provision of the highly efficient quad control set.
Does
any existing (actual real working) camera utilise this optimal front dial position ?
Some get quite close. The Panasonic GH3/4 almost make
it but there is un-necessary separation between the third and index fingers due
to the shape of the upper handle. This makes the buttons behind the control
dial very difficult to reach without shifting grip with the right hand.
Some Sony and Pentax DSLR style cameras with the
control dial in front of the shutter button almost make it but again there is
un-necessary separation requiring a stretch between the index and third
fingers. In addition the two are at different heights and the control dial is
on an axis away from that which would line up with the index finger.
I have trawled through many cameras present and past
on the Digital Photography Review website and have managed to locate only two
which come very close to the optimal configuration for shutter button /front
dial design. As a bonus each has a quad control set.
Samsung’s first ‘all designed/produced in house’ entry
into the ILC market was the NX10 of 2010. I bought and used one for two
years. The designers of this camera got
the relationship between the handle, shutter button and front dial just about
right.
Samsung followed up with the NX20 which is similar to
the NX10 but larger.
The NX30 and NX1 are the two cameras which I nominate
as having the handle, shutter button, front control dial and adjacent buttons
very close to the optimal as determined by my research.
Yes………...Samsung.
Now
to the rear dial
Although not optimal as a single dial,
a well executed rear dial is very useful to have on a twin dial
camera. A camera with twin control dials
can allocate one to aperture and the other to shutter speed for quick
adjustment in Manual Exposure mode. One dial can be allocated to direct control
of Exposure Compensation in P, A or S
Modes. Twin dials greatly speed up
scrolling zoomed files in Playback.
Rear dials diagram referred to in the text below. The orange blob is intended to represent the thumb in neutral position. |
Existing
cameras have rear
dials all over the place. My research
has led me to the view that there is one optimal location for a rear dial with
the rest being suboptimal or worse.
Please
refer to the diagram
with my apologies for its poor quality. I find it easier to make things
than draw them. But it illustrates 6
locations where rear dials can be found on various cameras.
Referring back to my little discourse on functional
anatomy the diagram shows that the thumb can move side to side as shown by the
arrows, without unduly disrupting the base of the thumb and its grip on the
back of the camera. The end of the thumb (terminal phalanx) can also flex
forward into the area occupied by #4 dial in the diagram. The movement more relevant to rear dial
position is the side to side one.
Notice that the thumb cannot move up or down
without releasing grip on the camera.
Analysing the benefits or otherwise of each rear dial position:
Photo courtesy of Digital Photography Review Olympus EM1 with rear dial in position 1. The right hand has to release grip and move up to operate this dial. |
1. Several cameras have a rear dial here. I have owned several of them. In order to
prevent the thumb from bumping into it all the time it must be set forward. Thus located it cannot be operated unless the
thumb rises up to get a purchase on it. But for that to happen the user must
release grip on the camera with the right hand, support the camera with the
left hand, move the right hand up, work the dial then put the right hand back
down again.
I call this juggling. Support for and control of the
mass of the camera has to be juggled from one hand to the next while shifting
grip with one or both hands.
Photo courtesy of Digital Photography Review Nikon D5300 with rear dial in position 2. Notice the small thumb support pushed over to the right as required by this dial location. |
2. Again, several cameras have a dial here. I have owned a few. The problem is that you
cannot have both a decent thumb support and a dial in this location. In order for the thumb to bear effectively
onto the dial it must lift over the thumb support, which therefore must be very
small and located way to the right side which, as I discussed in the previous
post, provides a suboptimal thumb position.
Photo courtesy of Imaging Resource Samsung NX1 showing rear control dial in position 3. This is not bad but there is plenty of space on this camera to put the dial in the optimal position 6. |
3. Here is a somewhat favourite spot also. This
position is not as ergonomically problematic as the previous two but is not
optimal either. I have owned several cameras with a UIM here.
It is rather too high and wide to the left for
comfort. The round module marked X on
the diagram is located where the thumb wants to go. There is no space for a
control dial here but I used the spot for a JOG lever in Mockup #13.
In practice operating a control dial in position #3
means moving the right hand position a bit. That’s not the end of the world but
there is a better way…..read on.
4. I have seen and used some cameras with a dial here.
This location is ergonomically absurd. The dial cannot be used for functions in
Capture Phase as the thumb is on it all the time.
Several cameras, mostly from Fuji, which do have a dial here benefit from an
after market thumb rest which slots into
the hotshoe, keeps the thumb off the
dial and allows the thumb to take on the desirable angled position.
Fuji would do its customers a huge service by simply
designing its cameras properly in the first place so owners don’t have to
resort to aftermarket handles and thumb rests to achieve some level of
ergonomic integrity.
5. Lots of cameras have a dial down here. It works
just fine for Setup, Prepare and Review Phase tasks but is not desirable for
Capture Phase as the thumb must be released completely from the camera in order
to access the dial.
6. At last we have arrived at the optimal location.
The control dial is embedded in a moderately prominent angled thumb support.
The dial has sufficient projection and serration that it is easily operated by
the thumb.
The thumb can easily swing right to operate the
control dial or left to operate the JOG lever without disrupting grip with the
base of the thumb.
Easy. Very small cameras probably lack the horizontal
width to incorporate a dial here but the solution to that is to use a front
dial, not a rear dial in a suboptimal position.
How
many cameras have this rear dial location ? Not many as it
happens.
Sony’s A77 and A99 do although the control panel on
both these cameras is very cluttered with buttons.
The enduring mystery at Sony is that some model lines
have a completely different control system from others. All models are used by
humans with the same hands and they all have to perform the same functions so
why the difference in controls ??
The Panasonic GH3/4 and FZ1000 have well positioned
rear dials which operate nicely. The A77 and FZ1000 have a strange cutaway
thumb support beneath the control dial for reasons which elude me.
Nothing I could find at Canon or Nikon fits the bill.
Summary Existing
cameras have front and rear dials scattered about as if the chosen location
were the consequence of whimsy or habit.
Ergonomic analysis shows that there is in fact an
optimum location for a front dial and an optimum location for a rear dial, just
as there is an optimum design for the handle and thumb support.
Many recent market reports are describing a dramatic
and accelerating fall in sales of all kinds of cameras over the last few years.
A major problem with many cameras is their ergonomics.
Some are quite good, many are suboptimal and some are horrible.
Camera makers, designers and product development
personnel need to get serious about ergonomic issues. They need to stop
dithering around with model variations which make no sense ergonomically and
start making cameras which are a pleasure to own and use.
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