i'm looking to get a flatbed scanner, and i have some q's. i was looking at a b&h catalog, and it says one thing for hardware resolution and something else for optical resolution( ex. 4800 hardware and 4800x9600 optical). wich is more important? and what is a good resolution to make 16x20 prints?
It's very hard to say what scan resolution specs might do for you without knowing what you are scanning as the original you want to make a 16x20 print from.
The hardware resolution more than likely refers to how small a step the scanning array of photodiodes can make; 4800 steps per inch. The optical resolution more than likely refers to both the steps per inch (4800) and the density of the photodiodes on the array (9600 per inch). What you need to look out for is inflated resolution numbers that use interpolation from the optical resolution; it's relatively simple to add interpolation in software, but it won't add any real image information.
I have used the Epson 4870 for over a year now. I have scanned BW negatives and color slide. Biggest print I have made from a 645 BW scan was 24+36. that was with a 3200 dpi scan. Monte Johnson.
I've used the 4870 for a year also and find the scanner to be extremely accurate with the files needing only a little work, if any at all, and I use the Epson driver.
I neglected to respond to the question about specifications re, (ex. 4800 hardware and 4800x9600 optical) The difference between the lower resolution number and the higher, is that the higher resolution is the result of micro-stepping, moving the scan bar CCD linear array in half-step increments, which results in pixel readings that are 2:1 rectangles and are then divided by internal processing to make output in square pixels via interpolation.
The lower number always reflects the actual count of CCD sensor cells per inch of scanned original, across the width of the scanner.
You might take a look at Epson's web site if you are considering an Epson scanner. I got a very good price on a reconditioned Perfection 3170 and it looked and worked like a new one - and left a couple hundred dollars in my pocket!