You guys are too technical.These thing drive me crazy but I 'm willing to learn.Cheers.Originally Posted by Maretzo
Resolution of lenses is expressed in lines/mm and an inch is about 25 mm. Since such lens resolution rarely exceeds 100 lines/mm, does it make a difference to scan with a resolution higher than 2500 dpi? (Which is equivalent to about 100 d/mm.)
Try this for a simplified description of determining resolution for scanning:
Most flatbed scanners, despite the manufacturers claims, rarely improve the resolution acquired from film above 2200dpi.
Decide on the maximum size of print that you are ever likely to make from a given image. (for example, 20x25 from a 4x5)
For most purposes 240ppi is a perfectly adequate resolution for producing prints on an inkjet printer.
Take the ratio of the desired print size over the original film size (20:4 = 5:1)
Multiply the print resolution by this ratio (240 x 5 = 1200)
Therefore, 1200dpi is the correct resolution to scan a 4x5 film to produce a 20x25 print.
After scanning, set the image resolution in Photoshop to 240dpi (disable the "resample image" checkbox) and you wil end up with an image that should measure 20x25 at 240dpi.
When printing the image, set your printer resolution to "photographic" or "best photo", depending on your preferences, the actual printing resolution number (1440/2880/etc) has nothing to do with the resolution of the image you are editing, only the quality that the printer works at. Do not attempt to alter the image resolution to match the numbers for the printer.
If you are sending files to a lab for lambda printing or similar, then they usually require 300dpi files; simply multiply the print size/film size ratio by 300 instead of 240 to get the correct scanning resolution.
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