Hello there,
This is Part 9 of my series of notes and comments on digital cameras for bird
photographers.
In this part I will discuss Power (mainly batteries).
Note: This has been the hardest part of these notes to write due to the
potential dangers involved with the nature of the materials used in batteries
and the possibility of injury and/or harm to the user, equipment or the
environment if the batteries are misused and/or inappropriately handled or
disposed of.
It is quite amazing what damage these innocuous looking devices can cause if
mishandled or mistreated.
Take care with batteries!!
Probably the major 'Problem' area for digital cameras, both pro and consumer
types, is "Power".
Digital cameras are POWER MAD and LOVE batteries!!!!!!!!
Bird photographers (as well as other 'nature' photographers) will probably be
affected by this problem more than 'studio' or 'happy-snapper' photo takers.
Bird photographers often seek out their subjects in remote locations and
they also will often need to spend more time with their cameras switched to the
'ready' mode.
For these reasons they will put great demands on the camera's power supply.
With the exception of the optical viewfinder in some models, everything a
digital camera has and does requires power from the internal power supply.
For example:
- the image sensor needs power unlike film which is 'powered' by the light
entering the lens;
- the zoom lens is driven by an electric motor (even the 'manual focus ring' on
the lenses of a couple of the better cameras is really just an electric switch
for a motor that moves the lens);
- the shutter button is really an electric switch for an electronic 'relay';
- in some situations (e.g., low light) the autofocus system may be assisted by a
visible or invisible beam of light from the camera;
- the storage card requires electric power;
- the LCD viewing screen is power hungry;
- most cameras come with a built-in flash;
- most of the shooting options and camera settings are accessed via an on-screen
electronic menu;
- etc, etc......
But.....due to the apparent fetish camera manufactures seem to have with
miniaturisation, the small size of most digital cameras means small batteries as
well.
Generally speaking digital cameras use one of two forms of battery:
- one-piece box-shaped units;
- standard cylinder shaped pen-torch type.
Technically the box-shaped units are the best.
They are usually Lithium-ion types (Li-ion) such as are used in many video
camcorders, some even being the same models.
If you already have a Digital Video camcorder you might want to check out the
Digital Still cameras that use the same battery.
You might be lucky and find something that suits you.
But, even so, due to size restraints batteries that fit the battery compartment
of still cameras may fit battery compartments of video cameras but not vice
versa.
Lithium-ion batteries are rechargeable, don't have 'memory' problems and have a
high capacity for their size.
They also have a high price.
They self-discharge at a noticeable rate.
They start to age from the moment they are made regardless of whether they are
used or not.
They also require a special charger.
Cameras that come with this battery should come with a suitable charger,
however, you might want to check out the option of a charger that operates
from a car cigarette lighter.
The 'genuine' model will be expensive and may only charge the battery while it
is in the camera.
A better option is an after-market model that is capable of charging a variety
of battery shapes and sizes as well as operating in the car or from mains power.
These batteries can often be 'fast-charged' in a couple of hours.
However, if possible, leave these batteries 'on-charge' for at least another
hour after the charger indicates they are 'charged'.
This ensures the battery is fully charged.
The 'Charged' indicator may not actually indicate a full charge but rather a
degree of charge sufficient to operate the camera for a 'reasonable' amount of
time.
This state of charge is sometimes called the "Normal Charge"......interesting.
Only use a battery-charger that is specifically designed for the battery you
are using.
Also, STRICTLY FOLLOW THE CHARGING INSTRUCTIONS that come with the battery;
incorrect charging techniques with Lithium-ion batteries have caused DEVASTATING
problems in the past.
Lithium-ion batteries should be available from most camera outlets anywhere but
don't expect to pick one up at a road-house in the middle of 'No-Where'!!
Cameras that use this type of battery probably can't use other types of
batteries but should have a socket for an external power supply.
Note: Check the battery voltage and pin polarity of the external power socket
before connecting an external power supply!!
Most 'consumer' type digital cameras are powered by the 'pen-torch' batteries
such as the common AA size cell.
Such cameras will use either 2 or 4 cells.
These cells come in a variety of 'flavours', e.g.:
- Carbon-zinc (standard and heavy duty; non-rechargeable);
- Alkaline (non-rechargeable and rechargeable);
- Lithium (These can be single cells or twin-packs; usually non-rechargeable).
- Nickel-cadmium (Ni-Cad; rechargeable);
- Nickel Metal Hydride (NiMH; rechargeable);
The AA type cell is the most practical type to use and is the most readily
available, in one form or another.
Some cameras may work with the carbon-zinc type but they are not recommended
mainly because of their very short life when used in digital cameras.
If you are desperate you could try them; they are not likely to harm the camera.
Alkaline batteries are suitable but the non-rechargeable types are not very cost
effective and my experience with rechargeable alkalines indicates that, to be
kind, the technology is far from proven.
The big advantage that Alkaline batteries have over the rest is their ready
availability.
They also have a very long shelf life having a very low self-discharge rate.
Lithium batteries have far greater capacity than Carbon-zinc or Alkalines but
are quite expensive, are non-rechargeable and are not the same as Lithium-ion
batteries.
Lithium batteries work well in extreme cold conditions.
True rechargeable batteries are the only way to go and the pick is the NiMH
type.
NiMHs do not have the 'memory' problem that Ni-Cads have (I know there is an
argument about this but I am satisfied it exists) and they generally have higher
capacity than the Ni-Cads.
Briefly, the 'memory' problem occurs when the battery is only partially
discharged before being recharged a number of times.
The battery 'remembers' this discharge point and develops the characteristic of
'switching off' when it discharges to this point subsequently thus effectively
reducing the capacity of the battery.
To avoid this problem, Ni-Cad batteries should be fully discharged before being
recharged.
I could go into a technical discussion about discharge characteristics of the
various types of cells but it really is not necessary.
The only characteristic worth knowing is that NiMH cells (and Ni-Cads)
often reach their 'discharged' point suddenly.
The camera monitors the battery status and should warn the user when the
batteries are nearly discharged, however, my experience has been that this
warning often is missed by the user or comes a milli-second before the camera
shuts down.
This can happen in the middle of a shot meaning that you probably have missed
that once-in-a-life-time picture.....sorry!
The lens may remain extended and you won't be able to 'close' the camera until
you insert a charged set of batteries.
So.....you should have a few spare charged sets in your kit.
It is impossible to say how many shots a set of batteries is good for because of
the variations in the way the camera is used.
Things that can affect the 'life' of a set of batteries include:
- how long the camera is in the 'sleep' or 'ready' modes; bird-photographers
will probably set the camera to a long 'ready' period (it really is frustrating
to find the camera has gone to sleep just as that bird has finally
co-operated!!);
- use of the zoom;
- use of the LCD for reviewing shots;
- constant deleting of 'bad' shots;
- picture quality setting;
- use of the inbuilt flash;
- constant use of 'burst' mode (taking a number of shots with one operation of
the shutter button);
- whether or not the camera is set for 'always focus' or not (in this mode the
auto-focus will be reacting to everything the camera 'sees' all of the time the
camera is switched on causing a great deal of lens activity whereas when this
feature is turned off the camera only focuses when the shutter button is
depressed to half-way).
- the age of the battery.
It is therefore very necessary to have several sets of charged batteries
available during a shoot.
The capacity of a battery cell (the quantity of electricity the cell is capable
of providing before being considered 'flat') is usually stated in the form of
Ampere Hours or, in the case of AA size cells, milli-Amp Hours (mAh).
This is basically a theoretical calculation involving the amount of time a
battery will supply a constant current to a set 'load'.
There are people who need to know and understand this (I used to work with big
batteries and had a fair idea what it was aboutthen, but now.......) but to the
average digital camera user it is meaningless guff.
However, manufacturers of NiMH and some Ni-Cad cells are now stating a capacity
rating on the labels.
Although these manufacture's ratings may be open to debate it is probably
worthwhile going for the ones with the highest rating.
I have NiMH cells ranging from 1200 mAh to 1700 mAh.
I have assessed subjectively that the 1700 mAh ones last longer than the 1200s
before requiring recharging so the labelled rating may really mean something
after all.
By way of comparison, the Ni-Cads I have are labelled 600mAh.
NiMH and Ni-Cad batteries each require their own special type of battery
charger.
Use of the wrong type of charger can cause damage to the battery or a failure to
produce a full charge.
The best method of charging both of these types of batteries is using a small
current over a long period of time, up to 14 hours.
However, the most common method is by means of a 'fast-charger' which will do
the job in 1 to 2 hours.
This probably shortens the overall life of the battery but does seem to be
viable and is certainly the most convenient method.
Once again, it is worthwhile looking for a battery charger that works off mains
power as well as in the car.
Some chargers will charge both NiMH and Ni-Cad batteries; read the instructions
carefully.
NiMH and Ni-Cad batteries self-discharge even when not being used so it is wise
to recharge your batteries prior to every photographic 'session'.
NiMH cells are fairly expensive initially and are not universally available.
The most likely places to find the best varieties of these cells is at camera
shops or electronics stores.
All rechargeable batteries will gradually lose the ability to attain and hold a
full charge.
Don't be surprised if you don't get the full number of 'recharge cycles' quoted
by the manufacturer; their tests will have been done under optimum conditions
which probably bear little resemblance to how you use the batteries in the
field.
Digital cameras that use AA type cells may also have a socket for an external
power supply.
Check the voltage and the pin polarities of this socket before connecting an
external power source.
Low voltage electronic circuits are sensitive things and are often designed to
suit the discharge characteristics of the batteries used therefore it is
essential to use ONLY the types of batteries recommended in the user manual and
DO NOT use any other even if they fit.
If you are considering carrying a supply of batteries on your next photographic
trip and plan to fly, it might be an idea to check the airline's policy on
carrying batteries on your person or in your luggage.
Believe it or not this has just been an introduction to the subject of digital
camera power supplies!
I have probably missed some worthwhile points but the info above should keep you
spellbound for a little while at least.
In the next part of these notes I will discuss external flash for digital
cameras, not good news unfortunately.
Cheers
Bob Inglis
Woody Point
Queensland
Australia
(Disclaimer:
Please note that these are my personal opinions gained from personal experience
and observation; other people may have other opinions and different experiences.
What I have written above is not intended to be absolute.
Anyone contemplating purchasing a digital camera for any reason or purpose would
be advised to seek advice from other sources as well.
Note that, except where a particular model of digital camera is mentioned, these
comments and notes are meant to be general by nature.
These comments and notes are not intended to be an endorsement for or a
statement against any particular brand or model of digital camera or other
product;
they are intended only to be a point of discussion for those people who may be
considering purchasing and/or using digital cameras for bird photography.
It should be realized that changes are occurring seemingly daily in this field
and therefore features and usability of digital cameras are changing also.
The types of digital cameras will change regularly as will the quality of image
produced.)
Birding-Aus is on the Web at
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