Choosing a scanner
Not everybody needs the same sort of scanner. Here’s what to look for when deciding which scanner is right for your requirements:
- Scanner: Do you need to scan images or documents? All scanners on test are image scanners, designed to predominantly scan pictures.
- Flatbed scanners can handle photos, bound pages and even some 3D objects. Some flatbeds can handle film (transparencies, slides, negatives) and usually come with guides for placement. Flatbeds may also have a sheet feeder (also called an ADF, or auto document feeder) and a duplexing unit, which scans one side of the page before automatically flipping it over to scan the other side.
- Film scanners only handle transmissive materials and are usually upright rather than flatbed. They come with holders for scanning multiple slides, transparencies or negatives. Note, however, that cheaper dedicated slide scanners are not necessarily better than flatbed scanners that also take film formats.
- Portable scanners are compact and can operate without mains power but may sacrifice features or quality for convenience. Some scan directly to a memory card and can be used independently of a PC.
- Document scanners are designed to regularly handle lots of text documents, digitising printed pages, including business cards. Typically in an upright configuration with a sheet feeder, they scan both sides of a page at the same time for fast processing of documents.
- Media: Reflective material includes photos, pictures, drawings and even 3D objects, such as coins. Transmissive material includes transparencies, slides and photo negatives.
- Format: What sizes do you need to scan? Flatbed scanners can commonly scan up to A4 or US Letter size, but some scan up to A3 size. Transparencies can be several sizes, most commonly 35mm, and negatives come in a range of common sizes.
- Resolution: The higher the scan resolution, the more detail captured and the larger the file size created. For scanning text, even a 200 pixels per inch (ppi) scan is good enough for most purposes, while 300 ppi is standard (at a one-to-one size ratio) for pictures, but if you want to enlarge the original a higher resolution is recommended. Most scanners handle at least 600 ppi, which is usually sufficient.
- Film scanning usually requires much higher resolution, however, because the original size of some media, such as photo negatives and 35mm slides, is so small. For film scans of small media you’ll want 2400, 4800 or even 9600 ppi. You may see scan resolution quoted as optical resolution, which is determined by the optics in the scanner. Interpolated means the resolution has been increased by using a software technique called interpolation, which creates extra pixels to make an image larger, based on calculations involving the surrounding pixels.
- Software: In addition to scanning software, the scanner may also come with software for editing and cataloguing your images, OCR software for converting scanned text into editable text, searchable PDF creation and business card scanning.
Film or print?
Is it better to scan prints or film? There’s a reason purists prefer transparencies to prints. With the right scanner, scanning trannies (slides) or negatives will yield better digital images than scanning photo prints. Apart from Polaroids (which are not of the highest quality anyway), slides and negatives are the originals and prints are second-generation copies of the film. As such, they don’t contain as much detail as the film they were made from. Use film where possible.
What format to save?
Most scanning programs will give you a choice of file formats in which to save your scans, though they will usually default to either JPEG (.jpg) or TIFF (.tif or .tiff).
JPEG is arguably the most common and compatible image format, used by most consumer-quality digital cameras and scanners and supported by most imaging software. The JPEG format lets you compress your scans to produce a small file size, but to do so it uses “lossy compression”. This means some image information is lost, the higher the compression used. You can vary the amount of compression, so for best quality pictures save at the lowest compression (ie highest quality). The JPEG format is great for creating copies of your images in smaller file sizes for uploading or sharing online or via email. JPEG stands for Joint Photographic Experts Group.
TIFF is the standard for commercial/professional printing. It can be saved uncompressed or with compression, but file sizes are relatively large. TIFF stands for Tagged Image File Format.
How best to store your scans? On your computer hard drive, obviously, where they can be catalogued with software for easy retrieval, slideshows, creating photobooks and sharing with others.
Of course, you should make sure your computer is backed up regularly, including all your photos, in case the hard drive fails or in the event of any other computer calamity (fire, theft, flood and so on).
Many people also archive their digital images to CD or DVD, which is a relatively cheap way to store them for posterity (preferably offsite where they are safe from the aforementioned calamities).
But if long-term optical storage is your goal, you should choose your brand and type of media carefully or your digital memories may not last so long after all. Not all optical discs are created equal and cheap discs won’t necessarily last for years. Over time – mere years or perhaps only months if not stored carefully – the optical disc substrate can degrade, making the disc unreadable.
For long-term storage, make sure you choose “archival quality” discs. They will cost a little more than the bargain bin discs, but they should last far longer – a claimed “300 years” in the case of some brands. Again, only if stored correctly.
How do you store them? It’s quite simple really: to give you an optimal optical media lifespan the basic guideline is to store all optical media in a cool, dry place out of direct sunlight which is free of dust and airborne contaminants.
DPI (Dots per inch): Refers to print resolution, or how many dots a printer produces in one linear inch to create an image. Standard photo quality is 300dpi.
PPI (Pixels per inch): The number of pixels (picture elements) per linear inch in a digital image.
Film format: In the context of this test, the size and shape of film used in still photography – the most common formats for scanners being 35mm, 110mm negative, i120mm, 220mm.
Filmstrip: Photographic film that contains one or more single images (frames).
Negative: Film with an image the inverse of a positive image, either in colour or monochrome. Negative film comes in all formats.
Transparency: A transparency is an unmounted positive photographic image on film — either colour or monochrome.
Slide: A slide is a mounted transparency. The most common size is 35mm (also called 135 film). It is exactly 35mm wide. This format was introduced in 1934 and quickly became the most popular format.