When using a good scanner to scan slide and negs for photographic printing what is the best scan resolution in dpi? My scanner docs say between 300 and 3200dpi that's a big difference. If I want to print a slide image at 11x14" what scan res should I use? I have tried 1200 dpi and the photoshop file size can be as larges as 500mb.

I am tring to come up with the right res to generate very good prints in various sizes. Anyone put a tble together as a guide?

-- Ted Villella (t.villella@att.net), November 13, 2002

Answers

A good rule of thumb is to scan at 300dpi for the size of you output. For example: if you wanted to print at 11x14 you need to scan at a resolution that will produce 300 dot per inch at 14 inches (your longest side). That means 300dpi times 14 inches = 4200. So, if your original is a 35mm slide, you can set your scanner to scan at 100% and 4200 dpi. Keep in mind that you can also re-sample in Photoshop. I just did a print that was scanned at 3600dpi (which creates a 12 inch print) and resampled up to 20x24 inches from a 35mm slide. It looked great and sold for $245. You can resample (bilinear) up to 100% larger than your scan and have a VERY nice image and it would take a VERY well trained eye to see the difference.

-- John G. Wilbanks (john@jwphoto.com), November 16, 2002.