Hi Damien,
Many thanks for your patience. I read the article on file size and megapixels, then your guidelines for scanning old photos and photographing old photos. They were helpful. I have been scanning at 600 ppi but only 24 bit. I have a scanner which can scan at 48 bit so I'll use that from now on. Some of the old photos I have only digital copies and they are all over the map as far as image quality and megapixels. I have to take what I can get as the images are coming from all different parties.
I hate to try your patience further but I took a look at some of the jpegs I had been given as originals and the tiff files I converted them to. I checked ppi, how many megapixels and how many inches. Here is the breakdown on 2 of my photos.
Image 1 jpeg: 72 ppi 34.417" x 45.889" = 8187312 pixels
tiff: 300 ppi 9" x 12"= 9720000 pixels
Image 2 jpeg: 72 ppi. 55.556" x 41.667" = 12000000 pixels
600 ppi 20 x 16.49" = 1.1872800 pixels
By saving the tiff files as much higher resolution but smaller image size I hoped to maintain or even improve quality without having a huge file. I also thought, maybe mistakenly that when it came to the fine details I was better off making these changes before attempting any restoration. Please correct me if I'm wrong....and I know you will.