Testing CT scanners: This Is How Much They Can Damage Your Photographic Film

Recently, Kodak, Fujifilm and ILFORD issued warnings on new and improved scanning technology (CT scanners) at airports and other transit centers causing severe damage to untreated photographic films.

Fujifilm noted that these new scanners could cause “fogging”, distortion of shadow details and general degradation of the image. Although I take Kodak, Fujifilm and ILFORD at their word, I had yet to see any examples of the effect of these new scanners on untreated film. As I was traveling through Amsterdam Airport Schiphol recently i figured i would sacrifice a roll of film to see what the damage looks like.

Before the results, I would like to talk a bit about my approach:

Methodology

Film, camera and exhibitions
Two unexpired rolls of Fujifilm Pro 400H from the same lot. One roll went through a new CT scanner and an x-ray scanner, the other (my check roll) did not.

I shot the film with my Hasselblad 500C / M with a Sonnar 180mm f / 4 CF lens. Ambient light between exposures was cloudy and did not change. I used two film backs and as such the time between exposures was minimal.

I took three exposures of four different subjects on the two reels, one “correct” exposure, one overexposed by a stop and one underexposed by a stop

For the sake of brevity, I have included only the results for a subjects (therefore including three images per roll).

Development and digitization
I processed both rolls at home in the same tub to make sure they were developed identically. To scan the film I used a Nikon Coolscan LS-8000 and scanned using VueScan software. I scanned the movie as an “image” and did not do any conversion in VueScan. The files were saved in RAW DNG format.

The analyzes were named and performed as follows:

  • No_CT_ + 0: It was my “check roll” that didn’t go through the CT scanner.
  • CT_ + 0_Locked: This was a “scanned CT” roll and used the same VueScan exposure settings as above.
  • CT_ + 1_Unlocked: This was a roll scanned by CT but used the exposure settings automatically selected in VueScan to see how much could be recovered.

I used this approach in order to see how the analyzes of my control and CT rolls differed based on the same parameters used. Scanners and scanning software will always try to optimize a scan and therefore it would be more difficult to compare the actual effect of the CT scan on the film. Locking the exposure for this test is an excellent method of comparison.

The third round of scans was designed to see how much VueScan could recover from the negatives scanned by CT.

This process was then repeated for the overexposed and underexposed exposures at a stop.

Inversion / negative treatment:
In principle, as the film is from the same batch, developed in the same tank, scanned using the same scanner and scanner exposure settings, two identical frames from each roll should look the same if the CT scan hadn’t worked.

I reversed my No_CT_ + 0 exposure using Negative Lab Pro, then “synchronized scenes” to reverse the CT_ + 0_locked exposure. After the inversion, I changed the colors, highlights and shadows slightly to No_CT_ + 0 and I copied them to my CT_ + 0_Locked scans.

For the last “recovered” scans, I reversed each CT_ + 0_ unlocked individually exposure and calibrated the output as best I could manually to match the No_CT_ + 0 exposure. In doing so, I hoped to find out how much the effects of the CT scanner, if any, could be mitigated.

This process was then repeated for the overexposed and underexposed exposures at a stop.

Results

After opening my developer box, signs of basic fog immediately indicated which film had been scanned. After letting the film dry, this fog was a little less noticeable, although still noticeable:

The film on the bottom went through a CT scanner and shows clear signs of base fog (the orange base is noticeably darker).

Although the film showed obvious signs of fogging, the footage was still clearly visible. I couldn’t wait to put them in the scanner and check out exactly what the exact damage was.

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Below are the reverse scans for my Fujifilm Pro 400H Check Roll that did not go through the scanner – No_CT_ + 0. Nothing new here: all exhibits look very similar, as you would expect from a professional color negative film. Nonetheless, it was nice to have checked this out for myself.

Scans in parentheses from left to right: an underexposed diaphragm, a “correct” exposure and an overexposed diaphragm.

Now let’s move on to the more interesting results. What would the images look like when scanning the scanned film?

First, the results of CT_ + 0_Locked, which used the same scanner exposure and inversion settings as the control. Given my methodology, if there was no damage, these should look the same. Well…

Scans in parentheses from left to right: an underexposed diaphragm, a “correct” exposure and an overexposed diaphragm.

The results are clear. There is an obvious degradation in the quality of the picture. The negatives were clearly fogged up from the CT scanner. This is most evident in the current setup for the underexposed image (left). as described above, these negatives were scanned with VueScan exposure settings locked on the control roller.

To see how much of this image degradation could be recovered, I unlocked the exposure settings and scanned again, allowing the VueScan to set the appropriate gain for each image.

Again, bracketed scans from left to right: an underexposed diaphragm, “correct” exposure, and an overexposed diaphragm.

It is clear that to some extent the images are be able to be recovered. However, there are still clear signs of fogging throughout the frame. This is most obvious for the underexposed frame. In addition, there are color changes in the image and loss of shadow detail. Finally, the screens passed with the CT scanner are significantly more grainy, as this 100% crop shows:

From left to right: control roll (“correct” exposure) and recovered CT scanned roll (also “correct” exposure).

Conclusion

It should come as no surprise then that my findings support the warnings issued by Kodak, Fujifilm and ILFORD. Nonetheless, I have found it useful to have a few direct examples of what happens when a photographic film passes through these newer CT scanners. In my experience, these scanners lead to heavily misted film, color changes, loss of shadow detail and a substantial increase in grain.

I should clarify that the film (in this case) was still producing images after going through the CT scanner and x-ray and, depending on your definition, are still somewhat usable. Some caveats and additional notes:

Although my recovered images were still usable, this does not guarantee that this is the case for every type of film and every scanner. Fujifilm Pro 400H is a “Pro” film and other offerings aimed at casual film photographers cannot. In addition, this test was carried out using a color negative film. Black and white negatives / slides and color slide films will undoubtedly have different responses to newer CT scanners.

In my opinion, you should always bring your undeveloped film in your hand luggage and request a manual inspection. I must also say that I understand that in these hectic times this post may not be so relevant. Nevertheless, after having accumulated this knowledge, I wanted to share it with the analog community. Be careful!

I am an amateur and only started with analog photography recently (relatively). I have done my best to create a fair comparison, however, it will by no means be as rigorous as the tests performed by Kodak for example. Please interpret the results as such. It is quite possible that I made some mistakes in this post or in my process. If you have any comments or don’t agree with anything, please let me know in the comments.

Finally, these images have been reduced to 2000px on the long edge. Full-size images 5500-6000px can be found on Imgur.

Thanks for reading and please share your thoughts and experiences in the comments section below.

~ Jelmer

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About the Author

I am Jelmer, an amateur photographer who started filming about three years ago. I mainly focus on landscape, travel and “everyday life” photography. I like to shoot in 120 and 35mm formats, mainly … View Jelmer Quist’s full profile and links

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