Scanners create digital copies of a physical document or photo onto your computer. Once there you can manipulate the document or image using appropriate software. It is like the concept of a digital camera as they covert light (analogue signals) into digital data.
One of the most common uses for a scanner is to take old photos, slides or film and digitise them. Once made into a digital copy, these files and images can be stored for archive purposes, displayed on a larger screen for viewing, or even allow for edits to be made on previously types or handwritten notes.
Before looking for the right scanner for you, its important to consider the following questions to know how to pick the best scanner for you after comparing the specifications of each scanner:
1. What will I use my scanner for?
2. How many times am I expected to scan per day/week/month?
3. What kind of user am I? (E.g. home, work/professional, photographer, designer etc)
4. What types documents/images are you going to scan? (E.g. A4 or A3 size, film, negatives,
slides etc)
5. Do I need the ability to scan wirelessly or through a network?
6. What kind of speed do I need for scans?
It’s important to know what sets each model of scanner apart to make sure you make the best decision for your purchase. In this buying guide, we will discuss the different categories and what to look for in the specifications in order to help you choose.
What are the scanners main categories?
What Do I Look for in Specifications?
What are the scanners main categories?
Considered the most common, a flatbed scanner as the name suggests uses a flat base surface to scan a targeted piece of paper on a glass panel. The light that comes form under the glass reflects off the paper and its contents are captured by an image centre in the scanning head. Flatbed scanners earned their popularity through their versatility and easy-to-use designs. They can print not only documents and images but also pages form books, newspapers and magazines. Flatbed scanners are generally not suitable for high volume requirements as they only scan one sheet at a time, unless they are equipped with an automatic document feeder (ADF).
Sheetfed scanners work by moving the documents through the device instead of a scan head like the flatbeds. These scanners will have a built in ADF which means that they are suitable for unsupervised scanning, perfect for those looking to scan at a high volume. While great for scanning in large quantities, these scanners are not recommended for those looking for high image photo quality. This is due to the movement in the sheet which could cause imperfections. Keep in mind that sheetfed scanners can only scan individual sheets and won’t work with bounded documents.
Photo scanners will generally come in the form of a flatbed scanner as they can capture the most light and detail. These scanners are high quality boasting a high DPI and will also be able to scan slides, negatives and film. Good photo scanners allow you to scan and enlarge an image without reducing the quality. Photo scanners can also either come with, or be used in conjunction with photo enhancing or editing software for the best result.
Image Sensor
Modern-day scanners use two types of imager sensors, CCD (Charge Coupled Device) or CIS (Contact Image Sensor). CIS is a more recent technology, used primarily in cost-effective entry level scanners. CIS scanners are smaller in size and are more energy efficient than CCD models, however the trade off is a slight loss of quality.
This spec is what can really set a scanner apart from the rest. The resolution refers to the number of pixels a scanner can capture and is often measured in dots per inch (dpi). High quality scanners can capture more information from an image then standard entry level document scanners and therefore provide greater detail and quality. High resolution scanners can also scan excellent images even at a lower quality. For example, a 600dpi resolution scan using a 1200dpi scanner can be better than scanning the same resolution on a 600dpi scanner.
In terms of optical resolution, 300 dpi is adequate for the average document scan, while 600 dpi should be good enough for high-quality scans and common photo scanning. 1200 dpi or higher is required only for highly-demanding graphics work/photo scanning and 3200 or higher for film/slides.
The bit depth refers to the amount of information a scanner is capable of recording per pixel. The larger the bit depth, the more colour and grey shades the scanner will observe and in turn this results in a better quality scan. With higher quality images also comes larger file sizes as more information is stored per pixel.
Dynamic range is a measure of a scanners ability to record different tones of an image. The range is the difference between the darkest and brightest optical density that the scanner can capture. The bigger the difference, the better quality you will have.
Speed of a scanner becomes more of a factor based on the frequency of use. The more you use it, the more likely you will require greater speeds to complete your work efficiently. Scanner speed is measured in PPM (pages a minute) or IPM (images per minute).
Keep in mind that the speed of a scanner is affected by certain features and settings. For example a higher quality resolution scan will take longer, as well as scanning duplex.
