Which DPI To Use When Scanning Film

I have a newer Canon printer that has a slide/negative scanner. In the set up menu there is a wide choice of DPI/resolution selections. What would a good dpi setting be for quality photos? The settings range from 300 to 4800 dpi. Thank you.

For 35mm film or slides, try 1200 PPI and 48 bit. Some people like to do as much adjustments/correction​s to the image as they can, right in the scanner software, but I prefer to do them in Photoshop.

ChasP505 wrote in post #11612845
For 35mm film or slides, try 1200 PPI and 48 bit. Some people like to do as much adjustments/correction​s to the image as they can, right in the scanner software, but I prefer to do them in Photoshop.

I don't have a bit choice, at least I don't see one. Thanks for your input, much appreciated.

James Emory wrote in post #11612883
I don't have a bit choice, at least I don't see one. Thanks for your input, much appreciated.

The software should give you a format to save your files in -- what are your choices?

James Emory wrote in post #11612883
I don't have a bit choice, at least I don't see one. Thanks for your input, much appreciated.

What does the manual say? (Sometimes the settings may give you a "16bit" option, which is the same thing. 16 x 3 = 48.) If you truly have no options, assume it to be 24 bit (to create an 8bit image file). And my suggestion of 1200 PPI is just a starting point. You may want to go up to 2400 PPI.

I had a 2400ppi film/negative scanner, later upgraded to a 4000 ppi one since 2400 really sucked, imo. No question, 4000 ppi. The 2400 ones were not worth saving, imo.

I doubt the Canon does true 4000 ppi.

tonylong wrote in post #11612909
The software should give you a format to save your files in -- what are your choices?

Oh, I have that. The choices are TIFF, JPEG/exif, and BMP, and I've got it set to TIFF which I believe is better than JPEG. It also has a box you can check for unsharp mask whatever that is. Why would you want to unsharpen a photo. Keep in mind I'm relatively new at some of these terms.

bohdank wrote in post #11616700
I had a 2400ppi film/negative scanner, later upgraded to a 4000 ppi one since 2400 really sucked, imo. No question, 4000 ppi. The 2400 ones were not worth saving, imo.

I doubt the Canon does true 4000 ppi.

If I recall correctly the resolution from flatbed scanners, when scanning at the higher resolutions, is overstated by up to 50% due to the CCD technology they have to use and the way the stepping motor works. OTOH a dedicated film scanner yields the full resolution that's shown in its specs.

James Emory wrote in post #11616782
Oh, I have that. The choices are TIFF, JPEG/exif, and BMP, and I've got it set to TIFF which I believe is better than JPEG. It also has a box you can check for unsharp mask whatever that is. Why would you want to unsharpen a photo. Keep in mind I'm relatively new at some of these terms.

I'd scan to TIFF and use the highest resolution you can while still having a file size that your computer can reasonably handle. For B&W images scan as color and convert to B&W in Photoshop.

Don't do unsharp mast with the scanner, but do it in Photoshop as one of your last steps.

Bob_A wrote in post #11616943
I'd scan to TIFF and use the highest resolution you can while still having a file size that your computer can reasonably handle. For B&W images scan as color and convert to B&W in Photoshop.

Don't do unsharp mast with the scanner, but do it in Photoshop as one of your last steps.

I don't use/have Photoshop, I use DPP and their recent update added the unsharp feature in their RAW editing window. Now I've got to figure out how to use that. I've read that some folks think using the unsharp mask is better than the normal sharpening adjustment.

Scan at 2400 dpi, 16-bit B&W or 48-bit color and save as TIFF. If your scanner has digital ICE, use it for color but disable it for B&W (or Kodachrome if you have it). Use unsharp mask if you don't plan on editing the scan afterward.

Before scanning you have to be clear in your mind why you are scanning them and just what you are going to do with the scanned files. If the purpose is to preserve them in case of loss of the originals you will scan larger than if your purpose is to merely provide thumbnails for a cataloging program. If you are sure they will only be viewed on a computer screen, 1200 ppi will be sufficient. It will also suffice if they will never be printed larger than 4x6 inches. From there up the relationship is linear; 2400 ppi for 8x12, 4800 ppi for 16x24. Consider sorting the wall sized sheep from the on-screen goats and setting your ppi accordingly.

Next you have to consider the question of storage space. A 48,000 ppi scan saved as a 48 bit tif will be 182 MB. 560 of them will fill a 100 GB hard drive. OTOH, a jpg reasonably compressed will be about 15 MB. A 1200 ppi scan saved as a jpg might be about 2 MB.

Finally, there's the question of time. If you are doing a big job it's a factor. A 4800 ppi scan takes four times as long as a 1200 ppi scan because the scan bar moves only 1/4 the distance between samples.

tzalman wrote in post #11617335
Before scanning you have to be clear in your mind why you are scanning them and just what you are going to do with the scanned files. If the purpose is to preserve them in case of loss of the originals you will scan larger than if your purpose is to merely provide thumbnails for a cataloging program. If you are sure they will only be viewed on a computer screen, 1200 ppi will be sufficient. It will also suffuse if they will never be printed larger than 4x6 inches. From there up the relationship is linear; 2400 ppi for 8x12, 4800 ppi for 16x24. Consider sorting the wall sized sheep from the on-screen goats and setting your ppi accordingly.

Next you have to consider the question of storage space. A 48,000 ppi scan saved as a 48 bit tif will be 182 MB. 560 of them will fill a 100 GB hard drive. OTOH, a jpg reasonably compressed will be about 15 MB. A 1200 ppi scan saved as a jpg might be about 2 MB.

Finally, there's the question of time. If you are doing a big job it's a factor. A 4800 ppi scan takes four times as long as a 1200 ppi scan because the scan bar moves only 1/4 the distance between samples.

Mmm, I just scanned/printed a negative at 1200 dpi and printed the pic on a 4x6 and the detail is amazing. Did not think it would look that good. I likely won't ever print anything larger than 8x10 and I guess before I start this monstrous project, I'll start at 1200 dpi and print an 8x10 and judge. If I feel it's too grainy, I'll kick it up to 2400 and repeat the process. I'm also thinking about just saving as JPEG although the scan/print I did do was saved as TIFF. I have a Seagate 1TB external drive so I'm not too concerned about storage. Thinking about getting another external drive (500MB) to keep my computer backed up and just use the 1 TB drive for photos. Thanks for everyone's help, have learned much from the gurus.

James Emory wrote in post #11617514
Mmm, I just scanned/printed a negative at 1200 dpi and printed the pic on a 4x6 and the detail is amazing. Did not think it would look that good. I likely won't ever print anything larger than 8x10 and I guess before I start this monstrous project, I'll start at 1200 dpi and print an 8x10 and judge. If I feel it's too grainy, I'll kick it up to 2400 and repeat the process. I'm also thinking about just saving as JPEG although the scan/print I did do was saved as TIFF. I have a Seagate 1TB external drive so I'm not too concerned about storage. Thinking about getting another external drive (500MB) to keep my computer backed up and just use the 1 TB drive for photos. Thanks for everyone's help, have learned much from the gurus.

For an 8x10 I'd target at least 3600 ppi to ensure you can print at 300.

1200 is a bit marginal for 4x6, but the quality issues aren't as noticeable when the output format is small.

Bob_A wrote in post #11618416
For an 8x10 I'd target at least 3600 ppi to ensure you can print at 300.

1200 is a bit marginal for 4x6, but the quality issues aren't as noticeable when the output format is small.

Thanks, will experiment.