Choosing a Digital Camera
Updated December 2004
On the morning of 26 November 2002 I was listening
to WCBS 880 AM in NYC, and they had a feature about how to buy a digital
camera. The announcer said all that mattered was pixels and optical
zoom, and then went on a brief diatribe about how digital zoom was nothing more
than cheap trickery. I grimaced and made a mental note to write this page
for my web site that very day.
If the purchasing choice were really that simple
you wouldn't have the massive model proliferation that you see in the stores and
mail-order outlets today. Right now you can open the B&H catalog (or
walk into their magnificent store if you're lucky enough to be in New York City)
and see more than 100 stocked models of consumer digital cameras from just the
top ten well-known brands. New models are being introduced literally
weekly, as the manufacturers keep raising the technology ante and leapfrogging
each other in features, performance and quality as they compete for market placement. This far eclipses, by a factor of
at least three,
the growth and diversity seen during even the most active years of consumer film
camera development.
First, let's talk about that radio feature.
I agree that pixel count definitely is
important. If your pictures will only be viewed on a computer screen, 2
megapixels is actually more than enough. 2 megapixels is also fine for
excellent 3x5 prints, good 5x7's or fair 8x10's. This statement has
to do with numbers... a camera with a 2 megapixel sensor gives you
pictures up to around 1600x1200 pixels. Most people these days have their
computer screens set to 800x600 or 1024x768, so they can't even see a 1600x1200 photo in
its entirety without scaling it down. A 1600x1200 picture printed at
300dpi (dots per inch) gives you a 5.3x4" print. 300dpi just happens
to be the native resolution of many color printers, so it translates cleanly. At 8x10 your print resolution will
effectively be only 160dpi, which is OK but not great. Never mind that your
printer advertises 1200dpi - a 2 megapixel image at that setting will produce an
image the size of an
ID card photo. So determine your printing needs
and set your purchasing goals accordingly. For the best 8x10's that will
survive close scrutiny, a 5- or 6-megapixel camera would be wise.
I agree that given a choice between optical
zoom and digital zoom, optical zoom certainly is preferable.
What digital zoom does is focus the lens' image onto a smaller portion of the
digital sensor and instruct the camera to scale up the photo back to the size
you wanted. For example, if you have a 1600x1200 pixel sensor and use 2x
digital zoom, the picture quality will really only be 800x600 pixels.
While this seems like a terrible thing to do, cheating yourself of all the available
resolution of the camera's sensor, it is still preferable to no zoom
at all. This is because your camera's auto-exposure and auto-focus
features won't be distracted by unimportant elements in the field of view when
using digital zoom. Optical
zoom is no panacea either, particularly with the more inexpensive compact cameras. All
that extra (and often just medium-quality) glass in a long, complicated zoom lens
robs light from the image reaching the sensor, lengthening exposure times or
requiring more sensor sensitivity (resulting in noisier, grainier pictures), and subjects
the images to more geometric and spectral distortions.
What else is important? Without getting
into an obsessive and unnecessarily detailed breakdown, I believe the top four
technical elements for most people (ignoring obvious starting points like
preferences for physical size and weight) would be macro ability, flash energy and
placement, shutter delay, and memory card format. Of those parameters,
only the last two are particular to digital cameras versus film.
Focusing distance: I take a lot of
close photographs of minute objects, both for artistic purpose and to post
photos of jewelry and other small items on eBay. This drove my decision to purchase a Nikon
Coolpix 950 a few years ago, which at a certain focal length can focus on objects less than one
centimeter away, so close that the camera can substitute for a good loupe or an inexpensive
microscope! The 950 could clearly photograph the manufacturer's laser
inscription on the skirt of a .5ct diamond. Try that with YOUR camera!
Flash energy: Most compact cameras
(not just digital) have relatively anemic flashes. It's terribly
disappointing to take a photo of something ten feet away only
to discover that only the foreground in front of the object was lit suitably. Pay
some attention to the flash guide number, which can give you a rough if not
wildly optimistic idea of how far the flash will reach. The distance
between the flash and the lens will also dictate how much of a problem red-eye
will be. The farther the better. Some cameras can yield an optional
pre-flash to reduce red-eye, but that rarely eliminates it.
Shutter delay: As someone who uses a
digital camera very often, I can tell you the most frustrating thing in the
world is pressing the button half-way and waiting a second or two for the green light to
actually take the picture. Unless all you photograph are fixed, inanimate
objects, shop for a camera with snappy shutter performance and cycle times.
Memory format: There are four
prevailing types of flash memory. CompactFlash (CF), SmartMedia (SM), SD/MMC
and Sony's Memory Stick. This requires some discussion...
I personally can't stand the Memory Stick just
because it's Sony's, it's proprietary and obnoxious like everything else Sony does, and as a result the memory and adapters
or readers cost at least 50% more than competing formats, without any tangible
benefits. In fact, it's inferior. The interface was slow and almost
immediately obsolete, which begat "Memory Stick Pro", and the biggest Memory
Sticks are usually one quarter the capacity of the largest Type-I CF cards yet
are only 40% smaller. If you already
own other Sony products such as a DV camera, PC, etc. then you've already
displayed your willingness to pay too much for cleverly marketed goods and you may wish to stick with a Sony
digicam just so the memory cards will be transportable. Otherwise it's
just foolish!
The remaining three formats have pluses and
minuses of their own. Prices seem relatively competitive among the
formats. CF is larger but also more durable. Because it's physically
larger, it generally can sport higher capacities. A variation called
Type-II CF is thicker and not all cameras can use it, but it can hold even more
RAM or even micro hard drives.
SM is thin and relatively fragile, and its
exposed contacts can make it more subject to oxidation and static damage, but it also takes
less space to store or simply to insert into the camera. This can help
yield smaller and better device designs.
SD and MMC cards - Secure Digital or MultiMedia
Cards, physically the same but only slightly different electronically - are even
smaller than SM but the former can support natively secured storage and some
even have tiny switches on them to make them read-only, like you would do with
floppy disks. These too have exposed contacts that can be subject to
static discharge and to oil contamination from your fingers. Now there are
xD cards as well, which are similar to SD but even tinier.
xD/MMC and SM do have the advantage that they can
fit neatly into wallets. Memory Sticks and CompactFlash cards are
progressively thicker formats that won't take their place so gracefully
alongside your charge cards.
Here's an interesting table of popular flash
memory formats, their physical size and respective largest available capacity
as of December 2004:
| Type |
Dimensions |
Overall |
Capacity |
| CF |
36.4 x 42.8 x 3.3mm |
5141mm3 |
8 GB |
| MS |
21.5 x 50 x 2.8mm |
3010mm3 |
2 GB |
| xD |
32 x 24 x 2.1mm |
1618mm3 |
1 GB |
Interchangeability of the cards between various
portable electronics may turn out to be desirable, depending on how you use
all your gadgets, so be mindful of what gadgets use which format.
Other things to think about are size and
shape, articulating camera bodies or displays, the ability to accept screw-on filters,
the ability to capture brief movies and/or sounds, viewfinder quality, USB or
Firewire or serial connection, maximum shutter speed, lens quality, light sensitivity, and
battery type. Many but not all of the parameters that follow are strictly
the domain of digital cameras.
Size and shape: Do you want a pocket-able
camera and if so, how big are your pockets and how much of a bulge are you
willing to tolerate? A design with an articulating lens and/or LCD is
great for shooting over the heads of crowds or for getting down to the floor for
infant pictures without lying down on your stomach.
Lens quality: You get what you pay
for. Period. Carl Zeiss is not God, either. You can get decent
lenses without paying for the name. The widest possible F-stop (smaller
numbers are better) is often a
fair guide of quality, if not at least a starting point, but don't rely on it
solely.
Maximum shutter speed: Think about this if
the camera will be used at sporting events, and bear in mind that it will only
make a real difference in daytime. Even bright stadium lights can't give
the camera enough light for stop action at a distance, particularly when at the
long end of a zoom, unless your camera also supports very high ISO settings
(read: ASA).
Movie capture: Video cameras make mediocre
still shots and still cameras make mediocre movies. If you're happy with
mediocrity, feel free to spend the extra money. You can get decent
quality movies from a digicam these days, but you'll still be limited to clip
lengths defined in seconds. Make note of the resolution and frame rates
available in these modes. For comparison, TV and video is ~30fps (frames
per second) and motion picture films are 24fps. You may wish to avoid digicams
that only offer 15fps.
Lens attachments: Most people interested in
compact cameras will never use filters or other attachments. Will you? Likewise for the few
consumer cameras that feature interchangeable lenses. If you think you
will, get a camera with a threaded barrel or some other facility for adding
filters and special-purpose lenses.
Optical viewfinder: Using the LCD all the
times sucks your batteries dry in mere minutes. Turn it off and use the
optical viewfinder when you can. But if the optical viewfinder gives you a
teeny, dark, muddy image then that's not a viable option, is it. Likewise if
your camera lacks an optical viewfinder altogether.
LCD viewfinder: A camera with no LCD
display at all robs you of the ability to
immediately check how your picture came out, which is one of the most valuable
aspects of digital photography. Even the teeniest digicam should have one.
A camera that has an optical viewfinder uses the LCD only when composing and/or reviewing can be a huge
battery saver.
Connections: Cameras with USB connections
offer a faster, easier way (than serial cables) to get the images from your
camera onto a PC without removing memory cards, worrying about flash memory readers,
etc. USB 2.0 is much faster if your PC supports it. Some high-end
cameras even have Firewire (aka IEEE-1394 or iLink) connections, but it is not
as widely adopted as USB and isn't necessarily going to be noticeably different
from USB 2.0.
Batteries: If the camera uses some
physically rare or unusual rechargeable battery and the cells decide they have just
taken their last charge while you're somewhere in Borneo, the natives will find
much amusement in your clumsy attempts to use a set of AA batteries, duct tape, hair
pins, a stick of Wrigley's and the sheared wire strands from an automotive
jumper cable to rig up power to your dead digicam. You can find AA and AAA
batteries anywhere, but good luck replacing some oddball lithium polymer
battery pack at the souvenir stand in Petra. No matter which way you go, always
carry spares.
Neophytes may stop here, and in fact probably should.
The brave may continue...
Ready for more details? If you are,
here are some of the finer points that I shop for. Think about JPEG quality and
the ability to save pictures in "RAW" or "TIFF" mode,
actual pixels versus "effective" pixels, burst modes, ISO range, hot
shoe or PC socket, manual focus, remote control or timer, sound with the movie
modes, program exposure modes, manual exposure control, video out and video
standards, cradle availability, tripod socket, weather resistance, LCD
display resolution, brightness and features, ease of use of the buttons and
controls, metering modes, auto-focus modes, ability to set white balance, DPOF compliance,
etc. You might also want to scrutinize the software bundle that comes with
the camera.
JPEG quality: Unfortunately this is
something that's not commonly published, and it requires some discussion for
clarity. Most digital cameras save the photographs in a file format called
JPEG, which uses "lossy compression" to reduce the files to manageable
sizes that are more economically stored. Lossy compression actually throws
away a certain amount of detail in your pictures. The lower the quality
setting of your camera, the higher the compression, and the more detail that gets
thrown away. The key point is that the quality settings on various cameras
do not necessarily compare directly. The best quality "fine"
mode on one camera could be as much as twenty percent better or worse than the
best quality setting on another camera. If you're obsessive about detail
in your pictures, compare the compression modes carefully!
RAW/TIFF: Some of the more expensive
cameras permit saving pictures uncompressed, in a few different formats such as
TIFF or RAW. The up-side is that the images are preserved completely
intact as the camera's sensor saw them, absolutely unprocessed. Truly the
moral equivalent of a film negative, but less fragile. The down-side is that these
images are up to tens times larger, take ten times as long
to save to the memory card, and take ten times as much space on your memory
cards. Some (not all) RAW modes are actually twice as efficient as TIFF to
save and store, but we're still talking five times the size of a JPEG.
Also, the TIFF format is a standard but RAW is not, so if you're comparing RAW modes you need to
shop around. Also, not all software can read all the different camera RAW
formats.
Effective pixels: Once again a short
discussion, and perhaps a painful reality check. First, the megapixel
math. Much like a megabyte, not everyone's definition of a megapixel is the same.
Technically it's supposed to be 1024x1024 (1,048,576), not 1,000,000 (one
million). Weird, I know. Plus, everyone rounds off the number one
way or another. So if you really want to know what you're
getting, dig into the specs a bit. That's when you will find out that
there are also ratings for "actual" pixels available on the camera's
sensor behind the lens, as well as "effective" pixels, which is what
the camera uses to store the final image. Naturally the manufacturers use
in their advertising whichever number is higher. On some cameras the effective
number is higher than the actual number, which I consider to be cheating.
The technical name for this is "up-sampling". In small amounts it's fairly
undetectable, but try resizing a 100x100 pixel image to 500x500 pixels, and
you'll see what I'm complaining about. Yet the horrible truth is, in spite
of my complaints about cheating, a 3 megapixel camera is in reality a 1 megapixel camera and even if
it were 3.5 actual megapixels, it's still up-sampling! The reason is that such a sensor,
at 3.5 megapixels, will
actually contain about 1.17 million pixels for each primary color. The computer inside the
camera then interpolates information between all the neighboring
"actual" pixels in order
to compute the colors on all the "effective" pixels for the final image. The
mathematical prowess involved is substantial, and you ought to be impressed that
all this is going on inside the camera in fractions of a second. The methods are voodoo
-like. Every camera does it a bit differently, none perfect, and the wisdom of those
methods translates to the differences in apparent quality of the camera's
captured images.
Burst modes: This also relates somewhat to
"cycle times". The cycle time is the time between taking one
picture and being able to take the next. A long cycle time can be inconvenient and can cause you to miss
photograph opportunities. Burst modes alleviate some cycle time
limitations, but have varying limitations of their own. Such limitations
may be the quality of the pictures taken in burst mode, how many can be taken, and how
quickly (in fps or frames per second). Often, those three parameters all
contradict each other. The best cameras allow several large, fine quality pictures in
burst mode without affecting the burst rate or number of photographs that can be
buffered.
ISO range: This is the light sensitivity of
the camera, and the numbering compares to the film speed ratings you often
see. The higher the number, the better ability to take photographs in low
light. Most cameras offer 100 to 400. Better cameras offer 800 and
up. The higher sensitivity comes with a penalty, just like the higher
speed films do. The result is a noisier, grainier picture at the higher
settings. A noisier picture also doesn't compress as well in JPEG form, so it may take 30%
or more space to store. The best digital cameras can capture noticably
cleaner images at the higher ISO settings.
Hot shoe / PC sync: Most compact cameras
are equipped with a flash that's good for no more than six to twelve feet at the
most.
This is barely enough for most dinner table shots, and would immediately show
its shortcomings at a party-size table! If you need more flash energy, the easiest path is to be
able to mount a standard shoe-mounted flash strobe onto the camera. That's
where a hot shoe comes in. A "PC sync" terminal, particularly
one that's high-voltage compatible, can be used to synchronize your camera with
other portable flashes and expensive studio strobes. Usually you will see
these only on "prosumer" (enthusiast) and professional cameras.
Manual focus: Handy in poor lighting
situations, macro photography, product photos, etc. Most compact cameras offer it
only in "steps". The more steps, the easier your job is, because
otherwise you have to re-position the camera to make up for the lack of fine
focus control.
Timer: A timer is nice to have,
especially if you want to be in your own pictures, or if you're taking low-light
pictures and can't steady the camera it can substitute for a remote control. Many cameras have a ten second
timer, which I find is a bit short. I prefer fifteen, which gives you time
to get into the composition, convince yourself to smile and get everyone else
to cooperate.
Remote: Wired remotes are good for
preventing camera shake when using a tripod. Wireless remotes are
even handier, allowing you to operate the camera from several yards away.
It can relieve you of that mad rush to get into your own picture and force a
"natural" smile. Some wireless remotes use radio waves and some use infrared light. The light
operated systems can sometimes be finicky in bright sunlight. A few
cameras can be operated from a personal computer of handheld device, usually
via serial or USB cables - helpful with things like time-lapse photography,
etc.
Sound movies: Amazingly, not all cameras
that can record movies bother to include a microphone! Unless you are
Charlie Chaplan, I think that's a bit peculiar, but make your own
decisions. A microphone also makes for a handy video dictation and
notation setup, and the EXIF/DCF specification for JPEG and TIFF files allows
for attaching
sounds clips to still photos. Likewise, not all cameras equipped with a
microphone are also equipped with a speaker, so be wary of that if you'll need
to hear your movie clips from the camera.
Program exposure modes: These are sometimes
handy preference modes that are designed to coerce the camera to prefer certain
exposure characteristics for certain broad scopes of photography, such as
sports, portraits, landscapes, etc. Skilled photographers tend to ignore
these modes, which are often just a safe compromise of settings, and use
program exposure with program shift, or priority exposure modes (i.e. aperture priority or shutter priority, where for
example you set the aperture and the camera chooses an appropriate shutter
speed), or they go for manual exposure control. That fact should not
lessen their perceived utility, however. Sometimes these "creative"
program settings are linked to other functions such as autofocus mode, so less
button-twiddling is necessary to set the camera for a particular purpose.
Manual exposure control: Allows manually
setting the lens shutter opening and shutter speed. Usually the camera will indicate
whether or not it thinks your composition will be under- or over-exposed with
the settings you choose, but
will let you do as you wish.
Video out: I don't personally know anyone
who bothers to plug their digital still cameras into televisions, but many cameras do
provide the connections to do so. And thankfully, those connectors are
(usually) not
as proprietary as the myriad variety of micro-miniature USB connectors that are
in use. If you think you'll be taking pictures in the US to show to your
relatives on their TV in Germany, get a camera that outputs PAL as well as NTSC.
Cradles: Some digital cameras come with
cradles or docks (same doodad, different terminology), which help simplify the
process of recharging batteries, uploading and printing photos, programming the
camera settings, etc. These are nice, but I feel you should still have the
option of using simple cables to allow connecting to other computers and
uploading while on the road.
Tripod socket: Do I really need to explain
this what a tripod or the tripod socket is? A convenience point needs to
be mentioned, however. Check to see if the tripod mount will interfere
with changing batteries, accessing the flash memory, connecting cables, etc.
And check to see if it's metal or delicate plastic.
Weather resistance: Don't underestimate the importance of weather
resistance. Even if you're not photographing the Brazilian rainforests, the most basic weatherproofing will help your camera repel other unwanted
liquids such as spilled soft drinks.
LCD display: The display should be as large
as practical, especially if you're nearsighted. The more pixels in it, the more
useful it will be for immediately examining the quality of your
photographs. It should be bright enough to view in sunlight, backlit to be
usable in low light, and should offer plenty of information about the
photographs as well as the camera settings. Beyond that, you might be
interested in digital cameras with LCDs that can be covered to protect
their fragile faces and manipulated to allow adjustable viewing angles and perspectives.
Ease of use: The layout and even the presence or
lack of presence of various controls and buttons can make an enormous difference
in the basic practicality of your camera. If you have to navigate through
five menu options on the LCD just to turn the flash on or off, you're going to
want to throw the camera into the garbage inside one month. Just the same,
the controls that are provided should be easily manipulated. And if you live in a
cold place, think about whether or not you can operate the camera's controls
while wearing gloves.
Metering: The camera can meter the lighting
and exposure conditions either through the lens ("TTL"), or using an
external sensor on the camera body. TTL is more accurate, particularly on
a camera with a zoom lens, since it's more reliably sensitive to the composition
of your photo. Metering can also have several modes, such as
"spot" or "average", or "center weighted".
These modes help the camera determine the correct exposure (or best compromise)
for tricky compositions, such as a backlit subject. The number of zones in
the viewfinder on which metering acts, and the pattern in which those zones
are laid out, varies among cameras. The number tends to be a selling
point.
Auto-focus: Most cameras are
auto-focusing. Some cameras have more than one
zone in the viewfinder, on which auto-focus reacts. This can be helpful
and sometimes, detrimental. The number of zones here too is a selling
point. Beware, the more you rely on fancy auto-focus, the
more that can go wrong. But as your subjects become more complicated it
definitely can be useful. Another thing to check for is whether or not the
camera has a focus assist lamp, to help the auto-focus work in low light.
Even if it does, remember the lamps only help for close-by subjects.
White balance: Digital photography has
brought the process of developing to the home computer. The down-side is
that people find out the hard way how much effort (hopefully) goes into the
color and exposure correction aspects of film developing. Digital imaging
sensors, just like film, can be influenced by certain light wavelengths in a way
that is not consistent with human vision. The result is that unadjusted
digital photos sometimes appear hideously discolored. The effect is
particularly noticeable under fluorescent lighting, for example. Many
digital cameras can compensate for much of the undesirable influences of certain
lighting, by allowing you to manually set the white balance. This employs
a process of showing the camera a purely white card under the lighting
conditions you'll be shooting in, before taking your shots. Many digicams
attempt to automatically set white balance, but do so with greatly varying and
mostly unpredictable results.
DPOF: Stands for Digital Print
Order Format, which is the standard that allows you to use your camera to flag
photos for printing, hand the memory card to a digital developer, and get your
photos printed to order. Nearly every digital camera now allows this.
EXIF 2.2: Stands for EXchangeable
Image Format, also relates to DCF, or the Design rule for Camera File
system. The EXIF standard describes how a digicam may store many kinds
of information about the photograph, the camera, its settings, sound clips,
thumbnail versions of the photograph, etc. right within the picture's file
itself. Version 2.2, a.k.a "EXIF Print", began to take hold in
2003, and is specifically notable because it offers color matching capability
when used with printers and software that supports the EXIF Print
standard. This goes a long way toward ensuring that what your camera
recorded in terms of brightness, contrast, color balance, etc. is what your
screen will display and your printer will print. EXIF 2.2 supercedes
Epson's PIM, or Print Image Matching standard, which never achieved universal
acceptance.
PictBridge: An established standard for
establishing communications between digital still cameras and printers, to
allow printing directly from the camera ("Direct Print"), typically via a USB cable.
PictBridge makes use of
DPOF to identify the photos to be printed. By itself PictBridge does not have any color matching
functionality. If you buy a camera and a printer that both support the
EXIF 2.2 and PictBridge standards, a little attention to your camera's white
balance setting at picture time is all that should be necessary for perfectly
rendered photographs, no PC intermediary or extra software necessary!
Software: Since your computer is
now going to be your digital darkroom, you should have software that
facilitates things like color and contrast correction, image repair and
modification, sharpening and softening, and perhaps some special
effects. Especially if you don't already have suitable software for this
purpose, you should shop for a digicam that bundles good image manipulation
software, such as Adobe's Photoshop. Other value-added software to look
for would be to help you upload images to web sites, print photo albums,
stitch together photos to create panoramas, etc. Watch out for the
difference between introductory, demo, and "retail" versions of the
bundled software packages.
I HOPE that I have given you a few things to
think about without completely confusing you. There are more aspects of
digital cameras that I have not covered, and plenty of detail has been left
out of the points I've covered, but I feel those points shouldn't need
explanation to people who need this kind of instruction.
If I haven't done a good
enough job or if you find errors, or even if you want to thank me, please find my Comments page on this web site and drop me a note.
And I can't say enough good things about Imaging
Resource, whose web site provides detailed and concise reviews on so many
digital cameras and which serves as my primary reference for all my purchasing decisions and
recommendations. Also highly rated is Steve's
Digicams. Try 'em both! You won't be disappointed.
FINALLY, a word about MONEY. Oh
yes, the nicer features will cost you. I know most people have budget
constraints to adhere to, but you may wish to exercise some flexibility there
and achieve a workable compromise between your budget and your desires.
Choose the features you really need and come up with the cash.
The few extra dollars you spend will be well worth the lessened frustrations.
Happy shopping!
