Scanner Upgrade Question

[markovich]

Hello, I have decided to scan our old family pictures and before I begin this time consuming process, I want to make sure that I'm getting the best quality scan I can get.

So after lengthy soul-searching, I've decided to scan using 600dpi instead of the common 300dpi, so that I have the option of enlarging in the future. When I scan a picture with 300dpi, it looks fine, but strangely, when I scan it with 600dpi there is a noticeable blur which I find unacceptable. From what I know about dpi, this should not be the case.

Could this be because I am using a 10 year old Canoscan N656U? I looked at the specs for newer Canoscans, and they don't look that much better than the one I have. Would you recommend buying something better for this job. I can't imagine that scanner technology changed that much in the last 10 years.

 

[Pgeobc]

I really don't know much about scanners, except that I recently bought an Epson V750 and the change made a big difference vs. my old scanner. My old scanner was a good Microtek that scanned negs, and pos up to 4x5s, so it was no slouch in its day. Evidently 10 years is an eon-type lifetime for a scanner.

 

[Dwig]

...I've decided to scan using 600dpi instead of the common 300dpi, so that I have the option of enlarging in the future. When I scan a picture with 300dpi, it looks fine, but strangely, when I scan it with 600dpi there is a noticeable blur which I find unacceptable. ...

One of two things is happening:

1. You are comparing the two images at different magnifications relative to the print. If you are viewing both images at "100%" in you image editor, the 600ppi scan is being viewed at twice the magnification, relative to the print, than the 300ppi scan. You will see much more blur in the 600ppi scan because prints don't retain that much fine detail; you are just seeing how the original negative's image was blurred in the print. A print only retains 200-300ppi.

2. Your scanner may only resolve 300ppi, as many older print & document only scanners did. When 600ppi is selected with such scanners, the image is actually an upsampled image, called "interpolated" in scanner jargon. This upsampling should retain very similar detail to a native 300ppi scan with some smoothing to reduce aliasing. The scanner software may be creating some additional blur while anti-aliasing the image.

I've found that with my EPSON v700, which has a true optical resolution of 4800ppi for reflected originals (prints, documents, ...) I get very slightly better print scans at 600ppi compared to 300ppi. Beyond that, I only improve the resolution of surface flaws and texture with not increase in actual image detail since such fine detail doesn't exist in the original.

 

[markovich]

One of two things is happening:

1. You are comparing the two images at different magnifications relative to the print. If you are viewing both images at "100%" in you image editor, the 600ppi scan is being viewed at twice the magnification, relative to the print, than the 300ppi scan. You will see much more blur in the 600ppi scan because prints don't retain that much fine detail; you are just seeing how the original negative's image was blurred in the print. A print only retains 200-300ppi.

I am viewing both images "to fit" the screen, not at 100%.

2. Your scanner may only resolve 300ppi, as many older print & document only scanners did. When 600ppi is selected with such scanners, the image is actually an upsampled image, called "interpolated" in scanner jargon. This upsampling should retain very similar detail to a native 300ppi scan with some smoothing to reduce aliasing. The scanner software may be creating some additional blur while anti-aliasing the image.

I've found that with my EPSON v700, which has a true optical resolution of 4800ppi for reflected originals (prints, documents, ...) I get very slightly better print scans at 600ppi compared to 300ppi. Beyond that, I only improve the resolution of surface flaws and texture with not increase in actual image detail since such fine detail doesn't exist in the original.

It could very likely be interpolated, I didn't think about that.

Could it also be that because the pictures were taken with very poor cameras (mostly 110 film, I believe), that it is impossible to scan to a higher dpi, because the data just doesn't exist in the picture?

If the limitation is in the print, then I don't want to spend the money on a new scanner, unless the difference will really be noticeable.

 

[Dwig]

...

Could it also be that because the pictures were taken with very poor cameras (mostly 110 film, I believe), that it is impossible to scan to a higher dpi, because the data just doesn't exist in the picture?...

Very possible and quite probable.

Simply looking at the prints with a decent lupe should easily show you whether there is any detail in the print that is not appearing in your scans. Classic "drug store" machine prints, particularly from small formats, are rarely as sharp at the paper's limits. Even when prints are as sharp as possible, the paper doesn't resolve detail significantly sharper than what can be see with the naked eye. ANY enlargement from a copy of a print will be somewhat unsharp.

 

[coreduo]

I have a Canon 440F which I bought for 125 dollars in Walmart. Yesterday, I scanned. My colored pictures which I converted to black and white turned out well like a picture taken by a 21 megapixel camera. My camera is a 35mm. Probably, I seriously imbibed Ansel Adams' famous rule. "If the sun is bright and you don't have a meter reading use f/16 and for shutter speed use the ASA number hence, my ASA is 400 so my shutter speed was 1/400 of a second." He further taught that, "if you are taking pictures from a shade, lower it to 2 to 3 stops. Mine worked perfectly. It all depends on Ansel's rules for shooting.

 

[coreduo]