Thanks for sharing your findings.  I have been bitten by the negative bug of late, and did lots of scanning of old pictures and negatives (well new negatives, as I have also been bitten by the film bug.  Lots of bugs going around.

I scan all of my negative (colour and b&w) at 3200 dpi, 24 bit.  Since I only print a few and display most on facebook, flickr or here, only 72 dpi is really needed, it is overkill.  The file size is about 50 mb per file. 

So while it is overkill, it is easier (at least for me) to edit and clean up.  So when downsamples to 72 dpi for web, or 600 dpi for print, the image looks better (once again at least to me)

The only downside  is that scanning takes about 30 minutes for a rack of negatives (12 images).  I use an Epson V500 scanner.  So i set up the rack, start scanning, then play games, or watch Fringe or something haha.

I scan everything to TIFF for what its worth.

It is lots of fun to be sure.

Ok I have rambled enough.  Once again, thanks for sharing your findings.

For archiving, I will stick with scanning at 2400 DPI for 35mm Color Negatives. This resolution gives more than enough pixels to produce an 8x10 print. Not that I ever would, but if I wanted to I'd have enough data to do so. For scanning prints (4x6 or 5x7), I found that 1200 DPI is overkill and produces an enormous file. Scanning at 600 DPI for Prints is plenty and again gives more than enough pixels for an 8x10. Both of these resulted in a file about 23MB in size. Not too bad considering hard drive size these days.

For Printing, resample images to 300 DPI. What I learned is that most labs print photos at 300 DPI. There are some specialty labs and higher-end photo printers that print at higher resolutions. But 300 DPI is a good benchmark. In fact, when given an image above 300 DPI, the lab printer will resample the image down to 300 before printing anyway. In the end, when I held an original 4x6 print side-by-side with the 600 DPI scan (resampled to 300 DPI for printing), they looked identical. And at some point, you have to call it good enough and move on. Otherwise I'd never finish the project.

Hope this helps someone. I'm off to start scanning!  

James

Since I will only have a few hours at each family member's house to scan the photos of interest, my approach will be to scan with printing in mind. The scans can always be batch-resized for screen display later. To prepare, I've been doing some experimenting to strike a good balance between scan time, filesize, and quality. Glad I did! I found out quickly that scan time and filesize can get gigantic depending on the settings selected. One combination resulted in a file that was over 1 GB for a single 4x6 print and it took almost an hour to scan!

After much experimenting, here are the candidate scanner settings I'm considering.

Prints
Original Size: 4-inch x 6-inch
Resolution: 1200-ppi
Bit Depth: 24-bit color (this value is set by the scanner and cannot be changed)
File Type: TIFF Uncompressed
Results:
   Filesize ~100-MB
   Scan Time ~1-Min

For comparison, doubling the resolution to 2400ppi quadruples the filesize (100-MB >> 390-MB) but only marginally increases the scan time. I need to find out if 1200-ppi is enough to make prints. I think it is.

35mm Color Negatives
Original Size: 36-mm x 24-mm
Resolution: 2400-ppi
Bit Depth: 24-bit color
File Type: TIFF Uncompressed
Results:
   Filesize  ~25-MB
   Scan Time  ~5-Min

I chose 2400-ppi for color negatives since they will have to be enlarged at least 4 times to produce 4x6 prints. But they take a long time to scan. Hopefully, I won't encounter many negatives during this project.

I'm going to send a few of these test scans to the lab for printing. I suppose that will be the ultimate way to find out if the settings will work. But I'm curious to find out what any of you have done for a similar project. Please share any tips, tricks, pitfalls, etc.

Thanks,

James