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!


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