How do you scan Kodachrome transparencies

Do developed negatives lose quality over time?

Long-term degradation of the film will depend on a few different factors, including the type of material it has been stored in and the temperature and humidity of the storage environment.

Of the four types of film to which most people are exposed (pun intended), black and white negative and Kodachrome slide films may be the least affected by age.

Black and white film consists essentially of silver crystals on an emulsion and, if properly developed / stored, will last a few lifetimes. All of my black and white films from over 20 years ago still look like I've put them up my sleeves.

Kodachrome slide film is this way because it is an additive film emulsion where the dye is in the processing chemicals and not on the film itself. It's been around since the 1930s and I've read reports that the 50 year old Kodachrome looked like the day it was filmed.

Now to the normal color slide and negative film. My stock of a few thousand at a time has definitely deteriorated over the past 20 to 25 years. Primarily, they've shifted in color (e.g. picked up a magenta hue) and certainly lost some of their saturation. Granted, I haven't seen most of these images in over 20 years, but I'd be almost willing to bet some have even lost detail and become grainier.

The main reason for this is that this type of film has the photo dye directly on top of multiple layers of emulsion. This dye can and will fade over time. Especially when you consider that most of the dye used on this film and the developing process it went through should never be archived. As the dye fades, the color and details (i.e. sharpness / grain) also fade.

Given this degradation, I was able to correct a lot of this either at scan time or in Photoshop and / or Lightroom, particularly the color shift issues. I attribute this success to the file format I used to scan.

Now for the scanning process. I selected a Plustek OpticFilm 7600I SE scanner for the task at hand and was very satisfied overall. As of this writing, this scanner doesn't appear to be available on Amazon anymore, but other models appear to be in stock.

I used the scanner's native, maximum optical resolution of 3,600 pixels per inch (PPI) for everything and selected it to save the scans in the best file format I know the scanner supports TIFF. With these parameters in mind, each scan took an average of 5 to 7 minutes for color and around 2 to 4 minutes for black and white. Each TIFF file was approximately 50MB in size.

Lastly, I wanted to point out that although the times for each scan were given above, some images took well over an hour, considering I fixed dust and scratches that the scanner along with the color and sharpness corrections won't fix could. And then there were some of my black and white negatives and Kodachrome slides that went through the entire workflow process in 10 to 15 minutes. In total, it took me about six months to select, scan, and repair about 800 out of a few thousand images I have on film. This only at night and on weekends.

mattdm

+1, but I don't think TIFF makes that much of a difference in the available compression range. If the scanner supports 16-bit TIFF, you can avoid posterization if you need massive color shifts. The main benefit, however, is to avoid compression artifacts and not to be customizable.

Light tight

@mattdm I agree. With film scans, you can even do a significant amount of the editing without posterization, because the film grain acts as a natural dither. TIFF is more useful as an intermediate format in order to save a high quality (95+) JPEG, or if you are planning extensive post-processing of the scan.

Light tight

PlusTek OpticFilm 8200i is a current successor to the 7600i. Basically, it's 90% the same scanner.