What makes a good scanner?

[FireGryphon]

Scanner reviews are hard to come by, and I know there are some serious graphics types in this forum, so I'm looking to glean a little knowledge from you guys.

Many years ago when I had my last scanner, I needed to install a separate controller card for it, and every time I turned it on or off I needed to reboot my computer. I assume that today, most scanners are USB and you can plug 'em and unplug 'em as many times as you want and they'll still work. The biggest deal, I suppose, is color and detail accuracy.

For those of you guys in the know, where's the best place to start when picking out a scanner? What do you look at? What specs matter? What do they mean? I'd learn how to fish than be fed, so to speak, so that I can find a scanner that fits my needs without just getting a plain recommendation.

[Aphasia]

What are you scanning, Do you need negative/slide ability ? Budget concerns? Other abilities?

Some of the larger makers the last years has been Canon, Epson and of course Agfa for photo-scanners. If its large scale automated document scanning then you have some serious gear from Fujitsu. Although in the later years Agfa was overrun really. Minolta did cheap neg-scanners which was good and competed with Nikon, until the newer Canons and Epsons multifunktion scanners ran over them in the low end sector. Otherwise Nikon made some of the best home-use negative scanner. Then you always had Imacon for professional work. And yes, you can get most scanners with USB 2.0 today, and probably a firewire one here and there. Earlier paralell was the most common for home use and SCSI for professional and SOHO-use. Thats usually what the extra controller card meant. That said, look at Canon and Epsons, thats pretty much where its at today.

If you need accurate color i would invest in a profiling kit or turn to somebody that can make a good profile for you. Which you might need anyway no matter which scanner you pick. Also, what you want to look at is optical resolution and what the stepping motor in the scanner can handle. Often you see measures as 1200x600 dpi. That means the optical sensor has 1200dpi and the stepping motor will do 600dpi. So for all purposes you are limited to smallest number in one turn. Also, some manufacturers give you a much larger number which infers interpolation. That is, the scanner will do multiple passes and then interpolate. I've never found that was worth it. Rarely gives you any more detail resolution and takes multiple amounts of disc-space and time.

If you are looking at the ability to scan transparacies you really need a scanner that will have a backlight, usually in the lid. There are some cheaper ones that use a kind of prism/mirror setup to get the light below to reflect back down, but thats pure crap really. But if you arent going up in budget, even a cheaper dedicated negscanner will be better.

Last and certainly not least, theres a variety of different software to use. Some is specialized for negative/slide use and other for scanning raster-images or OCR. So there might be a certain software packade that does something that isnt doe natilvey. I used Silverfast and Vuescan with my neg-scanner for instance. Most scanners also has uses TWAIN-drivers, that is pretty much standardized and which most software packages connect through.

[ozymandias]

http://www.xbitlabs.com . They run some scanner reviews. Generally, HP isn't very good and remains that way (historically they were the same), Canon is high end very good (their fare technology should be nice). Epson has the advantage of multi-os compatibility and generally good quality (don't try to run a canon in Linux - it might work on an HP, but certainly will not work with canon scanners).

[UberGerbil]

That old scanner was probably SCSI, though most of the ones that shipped with a card used a crappy SCSI card you couldn't use for anything else. Most of the high-end scanners are both USB and Firewire; the cheaper ones are USB only. Firewire is faster, but it won't make much difference except with the larger scans.

This site has some decent scanner reviews, though I haven't looked around there in a while.

Aphasia covered most of the high points. If you're scanning slides (and you don't want to pay for a dedicated slide/film scanner) you might want to look for a scanner that can a lot at once (some offer just a strip adapter that allows you to scan four at a time, while others offer a grid that can do 12 or 16 at a time, and software that will automatically separate the individual slides out of the scan). Some scanners offer a lid (and sometimes depth-of-field adjustment) that allows you to scan 3D objects.

It would help if you were more specific about what you're looking for and the kind of scanning you're planning to do.