Unfortunately, hurrying out the door this morning to teach a class, I hit the publish link instead of the save and close links. The "Can a Smartphone take photos of photos for uploading online?" post is not complete. But here is the rest of the story, as they say.
No. 4 Epson 8800F Flatbed Scanner
Now, if you examine each of photos carefully at magnification, you will begin to see differences. I opened all four of the photos in Adobe Photoshop and here are the results all at 400%. I magnified the same area in each of the four photos.
No. 1 iPhone at 400%
No. 2 Canon D5 Mark II at 400%
No. 3 Epson Sheetfed Scanner at 400%
No. 4 Canon 8800F Flatbed Scanner at 400%
You might note that the area shown in the iPhone photo is smaller than the area in the other three. The reason is the lower resolution. You can see if you look closely that the iPhone photo is markedly inferior to the other three. All of the others, including the Canon DSLR camera are about the same resolution.
Is a smartphone camera adequate for uploading files to online photo programs such as FamilySearch.org's photos? Yes, but it is not nearly as good of quality as a regular scan. Now, what if I enhance the Canon Camera photo?
Canon 5D Mark II with enhanced Camera RAW photo saved as JPEG
Now the same section of the photo at 400%
Understand that there is only so much information in a photo. No matter how or what you use, within limits, to duplicate a photo, you cannot exceed the physical limits of the original photo. All of these would be acceptable photos, but the ones taken with the iPhone and altered in Photoshop are not a detailed as the ones from the scanners.
If you consistently use a smartphone to take photos, you may want to consider the quality of the photos and think before you put them online.