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Photograpy & Video by Eileen Begley |
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| What You Should Look for When
Buying a Scanner Flatbed Scanners Scanner prices have dropped drastically in the last few years. You can now purchase a scanner for less than a $100. Or you can easily spend several thousand. Sometimes all the scanner specifications sound equal, so why pay more? What's the difference? I would put scanners into three categories: inexpensive/basic, midlevel and higher level. These categories overlap considerably now days. Inexpensive Scanners - CIS vs CCD CIS vs CCD, this is the main determining factor as to whether I would put it in the inexpensive category. Most inexpensively priced scanners, - $100 - $200 range will be CIS scanners (Contact image sensor) rather than CCD (charge coupled device). It will not give you as good a scan as a CCD Scanner. The image quality and color fidelity will not be as good. When you buy a CCD scanner you have moved into the midrange. Resolution - 600 dpi better than 300 dpi Inexpensive ones may do either 300 dpi or 600dpi. The more the better. Beware that many companies will give an "interpolated" resolution such as 1200dpi, 2400 dpi, 9600dpi. Only pay attention to the actual hardware resolution. Interpolation basically means the scanner guesses at what color pixels to add to increase the resolution. This is not recommended for scanning photos. If you have a 35mm transparency/negative adapter for a flatbed scanner with 600dpi resolution, then think "small." You will not get full detail for a 4 x 6 photo as the file size will be too small without using interpolation. If you want to scan negatives and transparencies it is usually best to buy a specialized scanner - or a flatbed in the over $1000++ range. If you are scanning 35mm film, then to be able to print an 8 x 10 or 11 x 14 photo you need a scanning resolution of 2700 dpi., which you will find in a specialized film/transparency scanner. Bits - more bits the better The next factor to consider is how many bits does it scan at? Many will scan at 8 bits per channel or 24 bits total. Others will scan at 10 bits per channel or 30 bits , or 12 bits per channel or 36 bits total. More are better. Most photo editing programs such as Photoshop only use 24 bits for most tasks. But more bits will give you a better scan anyway. You will get a scan with a better tonal range and better shadow detail. Scanner Software - they are not all created equal. Next factor to consider is the scanner software. You want to be able to preview the image, and be able to adjust the highlights and shadow areas. If you are looking in the inexpensive range, the software may be the deciding factor. A more expensive scanner should let you adjust levels with a histogram or adjust with curves. How you hook it up - SCSI, Parallel or USB? The last factor for this price range is how do you hook it up? You have three choices now. Some will hook up thru your parallel port and may then have a pass thru port so you can hook your printer to the scanner. Otherwise you will have to swap them back and forth. Watch out though if you have a lot of other peripherals attached to one parallel port i.e.; maybe a zip or jazz drive and more than one printer. Adding a scanner at this point may be the last straw. Your computer may rebel and crash. Second option is a SCSI card hook up. The scanner will usually come with the card included and will only run the one device on it. (You can buy special cards that will run multiple SCSI devices.) It's not that hard to do, but you will have to open your computer case to insert the card. Last choice is a scanner that hooks to a USB (Universal Serial port). Newer computers will have these and you just plug your scanner into the port. Density Range Once you move into the moderate price range there are additional specifications to be aware of. What is the density range? Once again, the higher the better. I have seen some rated at say 2.8 The Epson Expression for instance is rated at 3.0 There is a bigger gap between 2.8 and 3.0 than it seems. A higher density range will give you better detail in the shadow areas and a cleaner scan. If you are scanning film or transparencies, you want a range of 3.4 to 3.6 or more. Otherwise you will not capture the full range of the film. You will also have more of a problem with scanner noise and artifacts. Free Software One final factor is what software are they giving you for free?? Some will give you a limited edition version of Photoshop. (You can usually upgrade to a full version for half price.) Higher end scanners may include a full version of Photoshop. Other free programs may be included also. Sometimes the software may be worth more than the scanner, if you use it! Lens Quality It's good to read reviews of Scanners in the computer and other magazines. There are several things that do not have a rating so you can not compare them easily. One is the quality of the lens. A better lens gives you a better scan. You will have less noise and artifacts appear in the scan. Also a review will give you a comparison of the software. Inexpensive Scanners: CIS, 300 dpi to 600 dpi, 24 bits or more. Density is not usually rated. Scanner software may allow few adjustments to image. Mid Range Scanners: CCD technology, 600 dpi and 30 bits to 36 bits. Density range is often mentioned. Software should allow adjustment of highlights and shadow area. Higher Level: CCD technology, higher than 600dpi, 36 bits and occasionally 42 bits. Density range should be 3.2 or higher. Software should allow complex adjustments to shadow and highlight area, usually allow adjustment using levels with histogram and curves. |