Digital Focus: Scanners for Photographers
We demystify scanner specs and explain what matters most.Dave Johnson
Feature: Getting Started With a Photo Scanner
Every time technology changes the way we store memories, our old collections are at risk of being lost in the shuffle. When CDs replaced LPs, many of us had no way to listen to our treasured Humble Pie and Pretty Things records. With VHS steadily transitioning to DVD, I'm sure you're worried that you'll have no way to watch your collection of Star Trek and The Prisoner episodes. And now that 35mm film is starting down that same path thanks to digital photography, even our precious slides and negatives might become orphans.
One way to preserve your old photo collection is to get a scanner and use it to deliver your negatives, prints, and slides into the digital age. Not only does a scanner let you save those old pictures, but you can breathe new life into them as well. A scanner lets you share old, fragile pictures with friends and family--and perhaps even restore them digitally. Interested? This week, let's talk about scanners and how to shop for them.
Understanding Scanners
In many ways, a scanner is really just a digital camera--but instead of capturing the entire scene in a fraction of a second, a scanner methodically scans a line at a time as the CCD (short for "charged-coupled device"), which serves as the "eye" of most scanners and digital cameras, moves across the scanner's platen, or scanning bed. Indeed, a scanner's resolution is measured, in part, on the accuracy of the motor that steps the CCD across the platen.
What kind of scanner should you get? Flatbeds are typically the most versatile. Not only do they make high-quality images of photos and other documents, but they accept options like automatic sheet feeders that enable you to conveniently scan many pages. They can also scan almost any size document, from tiny business cards and 35mm slides all the way up to letter- or legal-size documents. Microtek's top-rated 2400-dots-per-inch ScanMaker 4900, for instance, can be found at the PCWorld.com Product Finder for as little as $130.
The major limitation of flatbeds, at least as far as we photographers are concerned, is that they usually lack the resolution to make good enlargements. They can also make poor scans of slides and negatives, even if you have a special adapter. I'll tell you why later, when we get to the section on dynamic range.
Personally, I use a film scanner. They are expensive, and vary dramatically in price, starting from about $500 at the low end to several thousand dollars at the high end. However, they deliver outstanding results. Film scanners are designed to accommodate slides and negatives and can usually reproduce pictures at a very high resolution--as much as 4000 dpi--which gives you rich, detailed digital images that you can print at full enlargement sizes. I love Nikon's 4000-dpi Super Coolscan 4000ED, for instance, which I found for $1069 at our Product Finder.
More on DPI and Bits
Like cameras, scanners are rated by resolution. Scanners, though, have two resolutions, such as "600 by 1200 dpi." The first number is the optical resolution of the imaging system; the second is the resolution of the step motor that moves the scanning head across the document. Since the optical resolution is always lower than the number of discrete steps the motor can perform, the first number--the actual resolution of the optics--is more important. You should rely on that number to compare scanners.
You also need to think about color depth. Some inexpensive scanners are 24-bit devices, meaning they can capture 16.7 million colors, which is near the number of colors that the human eye can see. More sophisticated scanners work at 30, 36, or even 42 bits per pixel, which translates to billions of colors. Scanners with more than 24-bit accuracy have more colors to choose from when resolving dark regions and images with lots of rapid color changes. This adds up to a high-quality image. If you are serious about scanning your photos, keep an eye on color depth and choose your scanner accordingly. If you're scanning snapshots or posting images on a Web site, color depth isn't as important.
One other point to remember: Some scanners cannot save images at their maximum rated color depth. These units can do high-bit scans, but their drivers may have to resample the data and convert each image into a smaller lower-color-bit file for saving and using.
Making Sense of Dynamic Range
The concept of dynamic range is a bit complex, so a lot people often skip the topic entirely. When scanning slides and negatives, though, I'd say that dynamic range is more important than the scanner's color depth--so it's worth considering. A scanner's dynamic range is a measure of how well the device can record changes in the brightness of the image it's scanning. It's measured on a scale from 0 to 4, where 0 is pure white and 4 is almost pure black.
The higher the scanner's stated dynamic range, the better it is at discerning shadows and subtle changes in dark colors. Every whole number change in dynamic range is a tenfold increase or decrease in light intensity: For example, a scanner that has a dynamic range of 4 is sensitive to a 10,000:1 range of light intensity in the scanned image.
So who should care about all this gobbledygook? Anyone who scans slides and negatives. Only film scanners have sufficient dynamic range (3.2 or higher) to make satisfying scans from film. Slides and negatives store a very deep dynamic range and you'll want a film scanner to have the best dynamic range you can afford, else you'll lose all the details in your shadows and darker image regions.
For more on shopping for a scanner, see "How to Buy a Scanner."
Dave's Favorites: The Pod
Digital cameras are compact and portable, but the advantage is lost since most digital camera bags are as bulky as a pregnant polar bear. That's why the Pod caught my eye. It's available for $49.95 from RoadWired.
The Pod is a small but spacious carrying case for digital cameras and other electronics that sits about 7 inches high and is 6 by 5 inches on the sides. A large main storage compartment in the middle offers enough room to hold almost any compact digital camera on the market. An adjustable, removable fabric "hammock" cradles the camera, offering a bit more protection from drops and jolts. It's a very clever design.
You'll probably want to carry more than just a camera in the Pod. Twenty pockets hidden in zippered panels can hold memory cards, batteries, extra lenses, and just about every other accessory imaginable. The whole bag is made of rugged ballistic nylon. It comes with several ways to carry it, including a removable shoulder strap and belt loops. This is perhaps the smartest and most versatile carrying case I've seen, and it's become a part of my arsenal.
Q&A: Should I Switch File Formats?
Recently, I've read about several file formats that are "better" than JPEG, which seems to be what everyone uses. One is JPEG 2000, an improved version of the JPEG standard. I've also seen a format that is supposed to make TIFF files as small as JPEG, but without the compression damage that JPEG does. It's called MyPhotoZip. What do you think of these?
--Ron Westerly, San Luis Obispo, California
An interesting question, Ron. While I always like to embrace better technology, we have to be smart about staying standardized with the rest of the world. A fuel-cell car would be wonderful, but if no gas stations offer hydrogen to replenish them, I think we're stuck with gasoline--or a hybrid approach using gasoline--for the time being.
The same is true with formats like JPEG 2000 and MyPhotoZip. JPEG 2000 may in theory be a somewhat better file format than good-old JPEG, the fact remains that popular image editing programs can't handle it; you'd have to use a special JPEG 2000-savvy program to convert back and forth whenever you wanted to edit the image. You also wouldn't be able to e-mail the image to anyone without converting it or using a special viewer. MyPhotoZip has the same problem--I wouldn't ask anyone to install a special viewer to look at pictures I sent through e-mail, but that's exactly what you have to do if you use MyPhotoZip. Sure, it promises a 500:1 compression ratio, but the reality is that it really doesn't look much different than JPEG, a universally accepted format.
My advice? Formats like these come and go. Forget about obscure, hard-to-handle file formats that offer only incremental improvements over what we already have.
Hot Pic of the Week
Get published, get famous! Each week, we select our favorite reader-submitted photo based on creativity, originality, and technique. Every month, the best of the weekly winners gets a prize valued at between $10 and $100.
A gentle reminder, folks: We disqualify some really wonderful pictures every week because the submissions don't follow the rules. Be sure to include everything we ask for in your e-mail message, including a description of your picture and your complete contact information, or your entry is wasted!
Here's how to enter: Send us your photograph in JPEG format at a resolution no higher than 640 by 480 pixels. Entries at higher resolutions will be immediately disqualified. If necessary, use an image editing program to reduce the file size of your image before e-mailing it to us. Include the title of your photo along with a short description and how you photographed it. Don't forget to send your name, e-mail address, and postal address. Before entering please read the full description of the contest rules and regs.
This week's Hot Pic: "Kayak," by Hubert Kan, Vancouver, British Columbia
Hubert says that he used a Nikon CoolPix 990 to take this photo of his son kayaking. A slow shutter speed allowed him to freeze the boat but blur the background, giving us a sense of action in the photo. Hubert captured this image by panning with the motion of the kayak as he pressed the shutter release.
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