Do negatives degrade resolution over time?

Question

I have a bunch of old negatives (~30 years old) that I recently sent out to a processing shop for scanning to digital. I was told that the scan resolution was slightly in excess of 3000dpi. I don't have any kind of equipment to do this myself, and am dealing with a local company.

However, when the scans came back, I was surprised to discover that many of the images looked more blurry than I remembered. I went back and discovered some old backups I had forgotten about, some almost 20 years old, which contains a few of the same images which had been scanned from prints, mostly on the order of 4x6. To my surprise, some of these images showed more detail in a lower resolution. For instance, one of the negatives scanned to an image around 3100x1900, while the print scan of only 2100x1600 shows detail which is fuzzy or blurry. Yet, it is not this way on all my images. On some of the images, the negative scan show more detail in which I can (for instance) read text which my print scan can't even resolve.

These results surprise me. I expect color changes, dust, scratches, that sort of thing, but not blurriness. I'm not sure if I should complain to the scanning service or ask for a partial refund and try somewhere else (I had a lot of pictures and paid a few hundred dollars up front), or if this is a legitimate possibility that time should degrade the resolution of the images. Many of the blurrish images were scanned from Disc format, and they claim the combination of the small size and the presence of the central hub contribute to the blurriness. However, since this I have discovered that even some of the 35mm scans are blurry. All of the blurry images are color (I suspect C41) negatives - I had B&W and color (positive) slides and even a few 110 negatives that turned out great.

update: I am attaching pictures to show a comparison of the detail in the original print scan and the higher resolution negative scan.

Here is the negative scan:

Here is the print scan, upsized using Cubic interpolation to approximately match the negative scan:

Here is the original print scan:

As I mentioned, not all of the negatives scanned blurry. Of those that did not, there is noticeable increase in resolution. For instance, this print scan (cubic upscaled for easily viewing):

And this negative scan, also upscaled to match size:

The grain is clearly visible and the text is verging on readable as compared to the print scan.

Answer 1

Negatives don't get blurrier over time, or not significantly so: I can imagine changes which might reduce edge sharpness very slightly, but probably not noticeably, and only if they were stored in terrible (very hot) conditions for a very long time.

Chances are, if you definitely have scans from the same neg one of which is blurrier than the other, that there was a focus problem in one of the scans.

Edit corresponding to version 3 of the question: that looks to me like the scanner was just not properly focussed at all. If you have a loupe, or any other fairly high-power magnifying glass, you should be able to diagnose this from the neg: look on the neg at the right-hand chimney: in the newer scan it's just a featureless white shape, but in the older one you can clearly see the front & side of the chimney are distinct surfaces. A decent scanner should be able to resolve film grain: this is not quite the same thing for colour negs, but it in any case should be able to outresolve the film, and this is nowhere near that.

These are just rubbish scans, you should not pay for these in my opinion: either get them to redo them or ask for your money back.

Answer 2

Negatives don’t change as to their sharpness. However the final outcome will be profoundly influenced by the methods, materials and equipment used to make prints. Before the age of digital, most folks took their film and or negatives to the drugstore or camera shop for developing and printing. The machines that did these tasks evolved over time. At the peak of the photo film photofinishing industry, films were developed in labs using high-speed equipment that could process and print, with high quality, thousands of rolls of film a day.

The printing equipment automatically analyzed each negative and applied corrective action to make an optimum print. I say optimum but the results were modified by the due diligence of the lab personnel. All and all, most such labs delivered prints with elevated standard (my seven giant labs anyway).

We are talking about the focus of the printing lens, the quality and surface type of the photo paper. Combine this with good quality control practices and the output was top-notch.

Today, few such photofinishing plants remain. Most are now small shops that scan negatives and print via ink on paper. The outcome can be terrific but often the scan density is low and quality control lackadaisical. Likely you will be able to find top-notch printing services but mostly the results will be hit and miss. Bottom line is, you get what you pay for (maybe). Take back the prints you don’t like and ask for a re-make. It’s your money so demand excellence.