Things to Consider When Buying a Digital Camera
Corey Satten, Corey @ u.washington.edu, 11/21/04

When I was shopping for a digital camera, I found comparing them to be really hard and it took some time just to discover what to compare. There are probably hundreds of models and the set of features and misfeatures to compare for each is large. I've written this mostly because friends keep asking for my advice and because there are some things I didn't discover until after I bought my camera that I wish I'd learned earlier. By sharing my experience, I hope to help you spend less time and end up happier with your choice.

Taking good pictures is part skill and part luck and with enough of either, I think any camera can take a good picture. The more skill you have and the more help you get from your camera, the less luck you need (on average). With that in mind, here is a very long list of things you may (or may not) want to consider when choosing a digital camera.

If you're picky, you probably won't find a perfect camera (at least I didn't). You will probably need to decide for yourself which features are most important to you and which cameras have the most of those features. Here are some links which may help with that: http://www.dpreview.com, http://www.imaging-resource.com, http://www.steves-digicams.com, http://www.dcresource.com. Also, I bought my camera from a local store because they offered a 2-week trial/exchange period (and I was glad I did because I traded my initial choice for a different make and model).

Aspects of Both Digital and Film Cameras

• Lens quality

  • Distortion (pincushion, barrel, chromatic).
  • Maximum aperture (smaller f-numbers let in more light).
  • Maximum aperture at telephoto is often significantly worse.
  • Resolution and sharpness. (Take pictures of newspaper classified ads to test sharpness--you can do this in the camera store).
  • Range of optical zoom. (Digital zoom is not really zoom--it is just cropping and magnifying--you can do the same thing in the computer after you take the picture).
  • Is there "image stabilization" (which can help compensate for camera shake when using a telephoto lens with insufficient light)?

• Exposure meter accuracy and intelligence (spot/average/matrix/etc.)

• Time lag between pushing shutter release and taking picture (may be dominated by slow autofocus on digital cameras).

• Full auto mode (point and shoot).

  • Not all models make good choices about what shutter speed to use. (The Nikon 3100, for example, will choose a 1/15 sec shutter speed on a telephoto shot rather than boost the effective ISO. This will probably result in a blurry picture.)

• Semi-manual mode (mostly auto with some manual overrides)

  • Aperture preferred: you set aperture, camera sets shutter speed.
  • Shutter preferred: you set shutter speed, camera sets aperture.
  • Focus and/or exposure lock (usually by pressing shutter-release half-way).
  • Scene modes can be like partial manual overrides if you can tell what they're doing (if the camera shows shutter and aperture settings the camera plans to use).

• Full manual exposure and focus control mode.

  • In manual focus mode, can you zoom in to focus accurately or does it just show distance in feet or meters?
  • Is it easy to use the built-in light metering in full manual mode or only in semi-manual?

• Focus accuracy and feedback (camera tells you what it autofocused on).

  • Some cameras indicate with little squares which areas are "in focus" but in my experience, the camera can lie about this (get the distance way off--especially for low light or low contrast subjects).
  • On the other hand, digital cameras tend to have much smaller lenses so they have better depth-of-field and focus, especially at wide-angle, may be less critical.
  • The Canon A70 lets you first autofocus and then press one button to transfer into manual focus mode at that distance setting. I find that very useful.

• Built-in Flash.

  • What is the maximum range of the built-in flash.
  • Can you use an external flash if you need more range?
  • For red-eye reduction, pre-flash works better than a steady light.
  • But red-eye is generally pretty easy to fix on a computer later.

• Close-focusing "macro" mode.

  • Some digital cameras can focus extremely close--some as little as 2 cm (1 inch) from the lens.
  • This is of more use than you might think. (You can take pictures of small parts you need to order or insects you need to identify etc.)

• What is the slowest shutter speed (for night photography)?

• Tripod socket? Is it metal? Would using it block anything important?

• Protection to keep the lens (and view screen) from scratching.

• Camera size, weight and ergonomics.

  (Smaller/lighter is generally better except small displays can be hard to read, small cameras tend to have fewer or smaller buttons and controls which may make them harder to use or more fragile.)

• Auto exposure bracketing.

  (Camera automatically takes 3 pictures at different exposures increasing the chances one will be good).

• Is there a real "off" switch or is there just a "deep sleep" where some power is still consumed checking whether the "power on" button has been pressed? If the camera has only a "deep sleep" mode, how much power does it use? Some cameras use enough when "off" that they'll run down an expensive set of lithium batteries in a year of sitting on the shelf. (You won't find this listed in the specifications for any of them).

• A self-timer mode (or remote control) for getting into the picture yourself.

• Weather resistance--some are much more tolerant of getting wet than others.

Aspects Mostly of Digital Cameras

• Purple Fringing!!!

  • Dark objects with strong backlight may be incorrectly colored purple (or blue)! Example.
  • This is one of the biggest disappointments I have with my Canon A70 camera.
  • There is a big difference between camera models on this. You've been warned!
  • It can sometimes be corrected with GIMP (free) or PhotoShop (expensive) but it takes lots of work.
  • It can usually be reduced by forcing underexposure (which is often easier to correct later).

• Megapixels

  • Remember it takes 4 times as many megapixels to make an 8x12 print as sharp as a 4x6 print.
  • You need 12.8 megapixels to get double the resolution of 3.2 megapixels.
  • You might not be able to see much difference in a print made from 3.2, 4, or 5 megapixels.
  • You can make a surprisingly large print from a 3.2 megapixel image.
  • Experiment for yourself by displaying part of a picture on your computer monitor and calculating how large a print it would make at that magnification.

• Digital Sharpening

  • Most digital cameras will "digitally sharpen" pictures before saving them.
  • A little bit of sharpening is usually a good thing but it introduces visible artifacts so some cameras let you control how much or little sharpening is done.
  • You can always sharpen later with software on your computer--you can't as easily unsharpen to remove the artifacts.
  • There is considerable variation between cameras in the amount of sharpening done by default.

• Are the colors accurate?

  • Can you adjust the white balance and color saturation?
  • Can you set the white balance by pointing the camera at something white and telling it to adjust accordingly? (That can give a more accurate white balance than any of the presets).

• What resolutions and JPEG compression levels are supported?

  • Higher resolution and lower compression both lead to better quality.
  • Can you use no compression at all (save in RAW or TIFF format)?

• Battery usage

  • Digital cameras use A LOT of battery power (much more than film cameras)! This seems to be largely due to the amount of computation required to capture and save the image after you take a picture and to continually update the display before taking a picture.

  • Although they all use a lot, some models use much more than others. Be sure to check how long a charge (or set of batteries) will last.

  • Can you save power by turning off the display? If so, is the camera sill usable?

    • Will it still briefly display the picture after you take it?
    • Do all the shooting modes still work with the display off?
    • Does it slow down camera operation to have the display off?
    • Can you change camera settings with the display off?

  • Does the camera use standard AA batteries?

    • If so, can you use standard (cheap-to-replace) NiMH rechargeable batteries?
    • In a pinch, can you also use alkaline or single-use lithium batteries?
    • The fastest AA NiMH battery chargers take only 10-15 minutes and charging batteries outside the camera means you can still use it while charging if you have another set of batteries.
    • Does the camera correctly detect the kind of AA battery in use and adjust the low-voltage threshold accordingly? (For example, the Nikon 3100 has a low-voltage threshold set for single-use lithium batteries. If you use NiMH batteries, after just a few shots are taken, it says the batteries are low and soon after refuses to use them).

• How complicated is the menu system? (Remember, a feature which is too awkward to enable won't get used.)

  • Are there shortcuts for common features/settings?
  • Can you bind settings to buttons or dials for simpler access?
  • Is the font legible (or too small to see)?
  • Is the display legible outdoors in bright light?

• Viewfinder type, accuracy, usability.

  • How accurate is the viewfinder?
  • What information about camera settings is visible in the viewfinder (if any)?
  • If camera settings can only be seen/changed on the screen, consider how useful the viewfinder will be if you can't see the screen without your glasses or in bright sunlight.
  • Some viewfinders are optical (like on film point and shoot cameras) and some are miniature screens behind an eye-piece (like video cameras).
  • Optical is clearer but usually less accurate.
  • Video is typically low-resolution, slow to update but more likely to show camera settings and be usable in bright light.

• Playback Magnification

  • After you've taken a picture, can you zoom in on the display enough to check if the focus is good or if there is purple fringing? (About 10x playback magnification is needed for that).
  • Assuming you can magnify 10x or more, is it reasonably fast to do so?

• Some cameras let you zoom and crop a photo you've already taken into a new photo (in the camera). This may be useful if you're going to print directly from your memory card but it may be more useful as a way of gaining more playback magnification (if the camera doesn't have enough to tell if a picture is really in focus).

• Which camera settings persist after you turn off the camera?

  • Are the choices sensible? (If you always want to take pictures at the highest quality, can you set that once or must you reset it each time you turn on the camera?)
  • Will the settings persist if you take the batteries out to charge them? If not all settings, at least the time and date?
  • Some cameras have a separate watch battery for keeping settings while the main batteries are out.

• Is there a panorama mode?

  • This lets you take several pictures which overlap and later "stitch" them into one (more or less) seamless picture on your computer. (Seamlessness takes care and effort).
  • Does the panorama mode help you compose your panorama by showing you a piece of the previous picture on the screen so you can line-up the next component picture?
  • Does the camera come with "panorama stitching" software which will run on your computer?
  • Does the software refuse to stitch pictures not taken in panorama mode (such as in manual or some other scene mode)? Some Olympus software has this limitation.

• Is there EXIF header display?

  • In playback mode, can the camera display all the modes and settings in effect when the picture was taken? Usually they're all recorded in the "EXIF" header in a JPEG file but not all cameras let you see the values on the screen.

• Effective ISO

  • Many cameras can automatically increase the effective "film speed" when subject is slightly beyond the range of built-in flash.
  • Do you get any control over this for other situations?
  • How much ISO boost is available? (Canon A70 goes from ISO 50 to 400)
  • How much ISO boost can be used before noise becomes unacceptable?
  • Some cameras have much less noise than others at boosted ISO.

• Is there a "best shot selector" mode?

  Some Nikons have this and it is fantastic. It lets you press and hold the shutter release and take 10 pictures in rapid succession and the camera will automatically choose and keep only the sharpest. If you're not using a tripod or flash and you need to use a slow shutter speed, this is much faster than taking a picture, reviewing it, deleting it, trying again and again until you get lucky and one is sharp enough.

• Some cameras let you attach voice memos to your pictures. This may be handy, though I haven't used it (because it is too awkward to do on my camera).

• Can one set the camera to take a series of pictures as long as the shutter release is pressed? If so, how fast can it take them? (Usually depends on size and compression settings).

• Can the camera take any pictures using just its built-in memory? Can the built-in memory be used to transfer pictures from one memory card to another?

• What USB protocols does the camera support?

  • USB 2.0 allows much faster data transfer than USB 1.1 (but either will work).
  • "Picture Transfer Protocol" (PTP) is supported on Windows XP and Macintosh OSX but not so well on older OS versions or Linux/Unix.
  • With the right software, some cameras can be operated (remotely) from a computer using PTP.
  • "USB mass storage" (which makes the camera look like a disk drive) works for all computers with USB and is also what you get if you take the memory card out of the camera and put it in a card reader.
  • Using a card reader also means you won't need to run down your batteries while transferring pictures from (or to) your memory card.
  • (Card readers cost as little as $10.)

• Video output

  Some cameras have video output so you can view your pictures on a TV (at low resolution). If the camera has this feature, it may also have a "slide show" setting where it will automatically cycle through the pictures. (This can be nice at Grandma's house if she doesn't have a computer.)

• Some digital still cameras can take short low-resolution video clips. If this is of interest...

  • Is there sound too?
  • Can you edit them in-camera?
  • What is the resolution, frame rate and maximum recording length?

• Type, size and speed of memory card

  • Whatever format you use, it may be wise to get two half-sized cards rather than one giant card so you have a better chance of not losing all your pictures at once if your card gets damaged or corrupted.
  • Flash memory has a maximum read and write speed usually given as 4x or 12x. Faster is better until the camera (or card reader) becomes the limiting factor. (I think x=150kB/s like CD speeds).
  • Some people think the older/larger "compact flash" is more robust and less likely to get damaged than some of the smaller formats (especially "smart media").
  • Occasionally airport X-rays can corrupt data on your memory card. A card format which you can carry through the metal detector (avoiding the X-rays) may be worth some consideration.