Wake On Demand in Snow Leopard
Putting your Mac to sleep saves power, but it also disrupts using your Mac as a file server, among other purposes. Wake on Demand in Snow Leopard works in conjunction with an Apple base station to continue announcing Bonjour services that the sleeping computer offers.
While the requirements for this feature are complex, eligible users can toggle this feature in the Energy Saver preference pane. It's labeled Wake on Network Access for computers that can be roused either via Wi-Fi or Ethernet; Wake on Ethernet Network Access or Wake on AirPort Network Access for wired- or wireless-only machines, respectively. Uncheck the box to disable this feature.
Series: Digital Cameras '99
Arthur Bleich examines key features in today's cameras, and offers his top picks
Article 1 of 2 in series
Since last year at this time, the winds of change have swept though the digital camera industry, blowing away most of the first generation failures and replacing them with a solid base of megapixel digital cameras that are a hair's breadth away from producing film-quality imagesShow full article
Since last year at this time, the winds of change have swept though the digital camera industry, blowing away most of the first generation failures and replacing them with a solid base of megapixel digital cameras that are a hair's breadth away from producing film-quality images. If 1999 looks to be the year you choose to become a digital photographer, this article will help you make sense of this often-confusing field.
I highly recommend that you check out the articles I published in TidBITS last year, as they cover many basic digital camera conventions, such as screen and print resolution, in more detail.
Resolution Recap -- When you begin researching digital cameras, you'll likely find yourself swamped by various numbers, such as pixel dimensions and image file sizes. In most cases, these refer to a camera's resolution, simply defined as the capability of a device to record fine details in an image, like individual threads in a sweater or separate grains of sand on a beach. Images from digital cameras (and scanners) are made up of little squares or rectangles called pixels. (Pixel is short for "picture cell" or "picture element.")
A digital camera's imaging surface is made up of rows of tiny individual light sensors (the sensor array) that capture color and light information, which is then electrically converted into digital data - the cells or pixels that make up the image. If a camera is capable of capturing an image that consists of 640 horizontal by 480 vertical pixels, it is said to have a resolution of 680 by 480 pixels, or 307,200 pixels (arrived at by multiplying the two dimensions).
The total sensor array is a charge-coupled device (CCD) and is used on most digital cameras now on the market. However, some cameras are being built around complementary metal oxide semiconductor (CMOS) devices, which are more reasonably priced and require very little power compared to CCD sensors. However, under certain conditions CMOS cameras sometimes produce undesirable electronic noise in the image.
If you can pack more pixels into a given area, you increase the resolution, which produces an image with finer detail. Think of it as using graph paper to help you draw a picture: the more squares per inch, the more nuances you can render.
If you want to make prints ranging from 5 by 7 inches up to 11 by 14 inches, consider buying a camera with as high a resolution as you can afford. Reasonably priced digital cameras are now available in the 800,000 to 1.6 megapixel range that will easily satisfy that requirement. However, if your images will be displayed on a monitor (or printed not larger than 4 by 6 inches), then a digital camera in the 640 by 480 range is all you'll need to accommodate the relatively low resolutions of most monitors.
Optical versus Interpolated Resolution -- Specifying digital camera resolution has become tricky lately, because some cameras offer both optical resolution, the actual number of sensors in the array, and interpolated resolution, a software-based method to increase the resolution of the optically obtained image by artificially adding more pixels.
Depending on the camera, interpolation can work well. For example, Agfa's PhotoGenie software, which comes with all but its lowest-priced camera, does an excellent job of interpolation when images transfer to your computer. You can also interpolate a picture from a low resolution camera within an imaging program, usually allowing it to be blown it up to a larger size without losing too much quality, depending on the quality of the original image. However, you can only interpolate (or "upsample") so much before your picture turns to pixel pudding, at which point no amount of digital manipulation can make it any better.
From Autofocus to Zoom -- Even though the terms are not unique to digital cameras, let's define autofocus and fixed-focus (or focus-free). Autofocus cameras automatically and accurately pinpoint whatever you aim at and record it as the sharpest object in the picture. Fixed-focus cameras have their lenses fixed (or locked) at an arbitrary distance calculated to keep most everything acceptably sharp from a few feet to infinity.
Because lenses used on digital cameras are of extremely short focal length, they have extraordinary inherent depth-of-field, allowing subjects both near and far to remain in focus, even when the lens aperture is wide open. So if your camera doesn't include an autofocus feature, it's no big deal unless you shoot big close-ups with a fixed-focus lens or expose without flash under low-light conditions (subjects or objects in the foreground may appear blurry). To compensate, some cameras feature settings to shift the point of focus manually, depending on whether you're shooting close-ups, portraits, or general subjects.
Finally, zoom lenses for digital cameras now come in two flavors: optical and digital. To make matters even more challenging, some cameras incorporate both. On a digital camera with an optical zoom, the resolution remains the same regardless of the focal length you choose. But a digital zoom uses only part of the sensor array and, unless it is interpolated, ends up exactly as if you'd cropped the image yourself - with resolution dropping accordingly. The Olympus D340L, for example, features a resolution of 1,280 by 960, but using the telephoto mode or the sequence shooting mode produces images that are only 640 by 480. Just remember: "Optical zoom, good; digital zoom, not so good," unless you shoot only for the Web or for CD-ROM multimedia productions, in which case it usually doesn't matter.
Recharge Your Batteries -- If rechargeable batteries don't come with the camera, I highly recommend getting some. Most digital cameras eat batteries like candy (the number one user complaint), especially since they must power the flash and the LCD screen used to preview and post-view shots (if the camera has an LCD). The best batteries I've found for most digital cameras are Quest nickel metal hydride (NiMH), made by Harding Energy and now sold everywhere.
Quest batteries hold a near-constant voltage when in use, and I've found they last four times longer than standard alkalines and at least twice as long as nickel cadmium (NiCad) batteries. And you can fully recharge them anytime, since, unlike NiCads (which photographers detest), they don't suffer from memory problems whereby they remember previous power levels instead of fully recharging. Although they can take up to 16 hours to recharge (from full discharge), Quests are so inexpensive (4 batteries and a charger for $35) you can buy several sets to always have enough on hand. If fast recharging is a must, a special charger has been promised soon.
For even longer-lasting power, I recommend one battery pack above the others. The Emberley ProPower 2.45, a featherweight NiMH rechargeable powerhouse that could put the Energizer Bunny into warp drive. Lasting more than twice as long as a set of Quests, it can double as an AC adapter, (which can cost as much as $65), and sells for about $99.
Storing Your Images -- Most digital cameras now use removable storage cards, with the two main types being either Compact Flash or SmartMedia. I've found them to be equally good, although presently Compact Flash cards have higher capacities. This can be a double-edged sword, though; it would be like using a roll of film that could hold 100 pictures, handy in one way but a little risky in that all your photographic eggs would be in one basket. Furthermore, it would take a long, long time to go through those images in the camera's playback mode if you had to. The main advantage to cards with more memory capacity is that they'll be able to store higher resolution images produced by the next generation of digital cameras.
SmartMedia cards are less expensive than their Compact Flash cousins and they can also slip into a FlashPath adapter ($99) can then be inserted into the Mac's floppy drive. Images then transfer faster than through a cable connection. (Don't confuse this capability with Sony cameras which use standard high-density floppy disks.) Both Compact Flash and SmartMedia are firmly established standards, so buy your camera based on its attributes and don't worry about the storage it uses.
Whether you store images on removable cards or the camera itself, you'll soon realize after transferring them to your computer that digital photos can quickly consume hard disk space. Higher-resolution images create larger file sizes.
Fortunately, many cameras allow you to select the degree of compression depending on the ultimate picture quality you require. On the Nikon CoolPix 900s, for example, available compression ratios are 1:4 (Fine), 1:8 (Normal), and 1:16 (Basic), with lower compression yielding better image quality than higher compression. In all modes, resolution remains the same. On some cameras, though, resolution also changes, so check the specifications. If a high degree of compression is acceptable, you can store more images in the camera or on its memory card. Expect to see compressed images grow from roughly five to twenty times in size if you open them in an image-editing application.
Also keep in mind that cameras compress the images using JPEG (Joint Photographic Experts Group) compression, which is a lossy method - some data is thrown out to conserve space. When you bring the image into your imaging program, save it as a TIFF-formatted file before doing anything. This eliminates the risk of it being closed as a JPEG file (which throws out more data) and becoming further degraded each time you save it.
Don't worry if you don't own an image-editing program such as Adobe Photoshop. Many digital camera manufacturers now include their own stand-alone programs that allow downloading to a folder, and some even have limited imaging capabilities. Another possibility is Adobe's cross-platform PhotoDeluxe, which is bundled with most cameras; other good software, like Microspot's PhotoFix (also bundled as PhotoStudio), should be given serious consideration. These programs are very inexpensive (under $100), easy to learn, require only a small amount of RAM and hard disk space to run, and have many features photographers will appreciate.
Until you pick the digital imaging program you want to marry - divorce not being an easy option in this field - you can do a bit of refining with those programs and then print your results. Some cameras, such as Epson and Olympus, allow you to bypass your computer entirely and print directly to one of their photographic quality printers, but in return for the convenience, you give up creative control of the final image.
Printing Images -- Although low resolution images are fine for the Web, printing them on paper changes things drastically. A 640 by 480 pixel image can be printed as an 8.8 by 6.6 inch photo, but the results could end up fuzzy or pixelated. If you want to print pictures as large as 5 by 7 inches, the camera should have 768 vertical pixels or more. Larger print sizes will usually require a camera with at least 960 vertical pixels (the vertical pixel number is the smaller one when resolution is described). However, some cameras with lower resolutions may be able to equal the results of those with higher pixel counts depending on the quality of their lenses and other design factors. Incidentally, many cameras offer a choice of high and low resolution modes. Use the higher one if you want prints, and the lower one for Web images or for sending photos as email attachments.
Into the Next Generation -- Digital cameras have now settled comfortably into their second generation. The 640 by 480 resolution cameras are mainly for snap-shooters who want to display work on the Web or make prints up to 4 by 6 inches. Megapixel cameras in the 1.2 to 1.6 million pixel range produce beautiful 8 by 10 inch prints (and larger) when output on inexpensive Epson 1,440 dpi PhotoStylus printers (the best, incidentally). The difference in resolution between 1.2 and 1.6 million pixels is often negligible.
Things improve every day. For example, some cameras can now even take multiple shots per second, whereas a year ago you would have been evaluating which camera had the shortest time lag between shots. (However, only a few, such as the new Olympus D620L can take multiple shots at their highest resolution settings - and you may still have to wait a minute or more after each half-dozen shots are taken for the camera to process the images.)
In the next installment of this article [which may have to wait a week or two because of Macworld Expo news -Adam], I'll offer my top picks for digital cameras currently on the market. Now that competition is heating up, there are some real bargains out there.
[Arthur H. Bleich is a photographer, writer, and educator who lives in Miami. He writes for major publications both in the U.S. and abroad, and is Contributing Editor of Digital Camera Magazine. He invites you to visit his Digital PhotoCorner, where you can find resources mentioned in this article, plus take an interactive course he'll be teaching called DIGIPHOTO 101.]
Article 2 of 2 in series
Digital photography continues to advance. In TidBITS-461, I talked about what to look for in a digital camera, and what has changed in terms of resolution, image storage, and printing since I first wrote about the field in TidBITS-407Show full article
Digital photography continues to advance. In TidBITS-461, I talked about what to look for in a digital camera, and what has changed in terms of resolution, image storage, and printing since I first wrote about the field in TidBITS-407. If you need to come up to speed on some of the terminology below, check out those articles.
Now it's time to focus on specific cameras that merit serious consideration. To make my short list, a camera must feature an optical viewfinder or reflex viewing in addition to its LCD screen. However, I've also listed an acceptable few without viewfinders, but which include LCDs that pivot so you don't have to hold the camera at arm's length. Cameras must also have an integral flash, a street price of $1,000 or less, and high marks from Internet users. All cameras come with transfer software - usually Adobe's PhotoDeluxe and a plug-in - and some also include other software.
All the cameras listed below will please you, and I've noted my personal favorites. I've been involved in photography for over 40 years, and my picks usually ignore bells and whistles that some folks like but seldom use, serving only to complicate camera operation.
Here's how current cameras stack up, grouped in order of increasing resolution and then street prices, rounded off to the nearest couple of dollars as of 15-Jan-99. Remember, though, you may want to pay a few dollars more to buy from a reputable dealer.
Low Resolution Cameras -- Don't assume low resolution means low quality. For Web design and images not intended for print, lower resolution cameras can be an excellent value.
Agfa ePhoto 307 (internal storage only, no LCD screen; $180): Built like a Panzer tank, this fixed-focus camera with a 43 mm equivalent lens has two resolution modes, shutter speeds up to 1/10,000th of a second, and an excellent software package. Internal memory stores 36 images at 640 by 480 pixels or 72 images at 320 by 240 pixels. The ePhoto 307 uses little power and batteries last a long time. Agfa has just discontinued this model, but they're still available and they've received nothing but high praise from users. Consider it plain vanilla, but oh, so good!
Fuji DX-5 (removable storage, no LCD screen; $195): Sized at 4.5 by 1.5 by 2.5 inches, this compact pocket camera has a fixed-focus lens, a pop-up flash, and a 640 by 480 pixel resolution. Fuji recently redesigned this camera, dropping the original LCD screen in favor of a bright optical viewfinder; there are also two manual aperture settings for different lighting conditions. The DX-5 is a great travelling camera, using SmartMedia storage and requiring only two AA batteries.
Olympus D-220L (removable storage, autofocus, LCD screen, and video out; $235): This is a sweet, compact, traditional-looking camera loaded with premium features, including a choice of 640 by 480 pixel or 320 by 240 pixel resolutions. Three user-selectable compression modes and superb glass optics give it better-than-expected images considering its pixel count. SmartMedia storage also makes this a gem for the price.
In a Class by Itself -- It's hard to place the $300 Agfa ePhoto 780 in any category, since it shoots 640 by 480-pixel images which its software can interpolate to 1,024 by 768 - something akin to digital alchemy in which extra pixels are spun out of thin air (for more information, see the previous article in this series). It's the fastest, slickest, and most usable advanced-feature digital camera in its price range. It has a bright optical viewfinder, simple controls, and takes just over a second to recycle between shots. Its LCD can also be used for viewing, and it brings up stored pictures as fast as you can press the button. It features removable SmartMedia storage, three focus positions (macro, portrait, and group), and a sexy, seductive design. And the pictures print out fine up to about 5 by 7 inches. To top it off, the ePhoto 780 comes with great software and video out. Who could ask for anything more? This camera is one of my personal favorites.
Medium Resolution Cameras -- When you need higher-quality images, but don't want to pawn your valuables to get them, turn to these medium resolution models. Each one uses removable media.
Olympus D-320L (autofocus, LCD screen, video out; $325): This camera features 1,024 by 768 pixel high resolution, and 640 by 480 pixel low resolution, offering absolutely brilliant images up to about 6 by 8 inches. The D-320L takes SmartMedia storage cards, features fine glass optics, and delivers finer picture quality than its resolution would indicate.
Sony MVC FD91 (optical zoom, LCD screen, viewfinder; $855): With a new progressive-scan charge-coupled device (CCD) producing a 1,024 by 768-pixel resolution and using almost-ubiquitous floppies, Sony seems to have hit the mark with this Mavica model. Multiple resolution choices, in-camera disk-to-disk copying, audio support, a phenomenal lithium-ion battery good for hundreds of shots before recharging, a rapid-fire mode, aperture and shutter priority choices, macros, and numerous other features make it almost too good to believe. It will even shoot up to one minute of MPEG-compressed video. Of Sony's new FD series, only the FD91 has a color viewfinder and an LCD viewer- the other Mavicas will still give you the feeling that you're holding a rifle at arms' length as punishment for not spit-shining your shoes. With a humongous 37 mm - 518 mm optical zoom, this camera should become a favorite of sports and nature photographers.
High Resolution Cameras -- So you want to grab as much image information as you can? Look no further than these high-powered models. (All use removable storage cards.)
Fujifilm MX-700 (also Leica DigiLux; autofocus, digital zoom, LCD screen, video out; $455): Looking like something built for James Bond, this miniature silver beauty captures images in 1,280 by 1,024-pixel resolution with 640 by 480 as an alternative. Wildly loved by its users, its main drawback is a low-resolution 2x digital zoom. It needs five seconds to recycle between images (12 with flash), offers three compression modes plus SmartMedia storage, macro capabilities, and a lithium-ion battery that can power over 150 shots between charges.
Nikon CoolPix 900/900s (autofocus, optical zoom, LCD screen, video out): 1,280 by 960 pixel resolution with outstanding color and "right-on" exposure. These CoolPix cameras offer three metering choices, an optical zoom viewfinder with diopter correction, a see-through LCD shield that protects against finger marks, and a swiveling 38 mm - 115 mm (35 mm equivalent) Nikkor zoom lens with the closest focusing macro of all. A manual override mode, an external flash synch on the 900s for Nikon flash units only (using others will hurt the camera), and a host of other goodies make these cameras top-of-the-line choices and one of my personal favorites. The CP900 is $570, while the CP900s is $635.
Olympus D400Z (autofocus, optical zoom, LCD screen, video out; $665): This is a remarkable new camera incorporating both 3x optical (35 mm - 105 mm) with a 2x digital zoom boost (at any optical focal length). With a 1,280 by 920-pixel resolution, the D400Z is right up there in pixels. The package includes a FlashPath adapter for transferring images directly to your computer through the floppy drive. You can also shoot uncompressed TIFF images, a novel feature that eliminates JPEG artifacts- but don't expect to store more than a few on each SmartMedia card. Still, for special shots, it's a unique capability on a unique camera.
Agfa ePhoto 1680 (autofocus, optical zoom, LCD screen, video out; $740): An extraordinary camera that beats all other swiveling designs hands-down on ergonomics, the ePhoto 1680 offers an optical resolution of 1,280 by 960 pixels and can further interpolate an image to 1,600 by 1,200 pixels. Alas, it has no optical viewfinder, but I've not found that to be a drawback on this particular camera or its slightly lower-resolution cousin, the ePhoto 1280. A 38 mm - 114 mm tack-sharp optical zoom lens and some of the easiest-to-operate controls make this camera well worth a look.
Olympus D-600L/D620L (reflex viewing, autofocus, optical zoom, LCD screen): These cameras provide resolutions of 1,280 by 1,024 pixels with an alternative resolution of 640 by 512 pixels. (The new D620L allows fast shooting - up to 5 high-resolution images in 3.6 seconds - along with external flash synch for any brand of flash and some extra goodies.) Both have a 3x zoom lens (36 mm -110 mm equivalent) and support for SmartMedia cards. The size of their sensor array is directly proportional to an 8 by 10-inch print, which means no wasted pixels printing at that size. Even though they lack video output, they're among my personal favorites. The D600L is $705, while the D620L is $995.
Boldly Going Where No Digicam Has Gone Before -- My evaluation unit of the unusual Minolta Dimage EX Zoom 1500 camera hasn't arrived yet, so I can tell you mostly that it's a major upgrade from the lower resolution model I thought was pretty neat last year, priced at $735. Its uniqueness lies in its detachable lens unit, which you can place anywhere at the end of a five foot cable tether. I'm sure you can think of a few creative uses for this feature.
But that's just the beginning. I'm impressed with its high 1,344 by 1,008-pixel resolution (including uncompressed image capability) and compact flash memory storage, plus its ability to shoot 7 frames in 2 seconds at high resolution. The camera also offers manual control of f-stops and shutter speeds and an equivalent 38 mm - 115 mm optical zoom. It has both an optical viewfinder and LCD viewing screen, shutter speeds from 1/4,000th to 2 full seconds, a 640 by 480 low resolution mode, video output, and future optional lens units and resolution upgrades. As Agatha Christie's fictional sleuth Hercule Poirot would say, those little grey cells at Minolta were working overtime here. This camera is bound to become one of my favorites and - fair warning - Minolta may have to send out a SWAT team to get my evaluation unit back.
Depth of the Field -- Don't feel bad if your beloved digital camera isn't listed here - that means nothing as long as you're happy with it. Last year, I received multiple email messages from readers who entered into battle with me because the two Sony Mavicas then on the market weren't listed. Although those cameras produced awful low-quality freeze-frame video images and had horrible LCDs, they sold like hotcakes because users were enthralled by the cameras' use of cheap floppy disks. And so was I, until I realized I was homing in on one interesting feature that didn't make up for other shortcomings. And, believe me, I tried my best to include a Kodak camera this year, but their low-end models all come up short and their high-end ones are downright Mac-unfriendly.
There's no "right" camera; only the one that's right for you. And if it isn't, buy another. That's the point of my picks: to help you identify the wheat among all the chaff. Just as you'll buy more than one computer in your lifetime, you'll do the same with digital cameras. There will always be a better one just around the corner, and there are no fatal mistakes when it comes to buying digital cameras. Recognize that, and just build your picture-taking skills with the camera you choose (or already have). As your skills improve, you'll know exactly what features you'll want on your next camera.
More Information -- A wealth of resource material covering everything mentioned in this article, other digital photography sites, price comparison sites, and a major online merchant list may be found at the Resources section of Digital PhotoCorner. You'll also find other informative material relating to digital cameras and imaging at the site.
[Arthur H. Bleich is a photographer, writer, and educator who lives in Miami. He has done assignments for major publications both in the U.S. and abroad, and is Contributing Editor of Digital Camera Magazine. He invites you to visit his Digital PhotoCorner where, among other things, you can take an interactive course he'll be teaching called DIGIPHOTO 101.]