Adox CMS 20 II: An Ultra-High Resolution Film Review

Adox CMS 20 II is the “highest resolving image recording system in the world.”¹

According to the manufacturer, this 35mm film can yield 500-megapixel images when scanned, beyond even the highest-resolving full-frame digital cameras. However, it needs a special developer to produce a workable dynamic range — otherwise, the photos may show extreme contrast.

In this review, I share my experience shooting and processing this film with the specialized Adotech CMS IV developer as well as the non-specialized Ilford DD-X, discuss its technical specifications, and share the results of my attempt to produce a 400-megapixel scan (the absolute maximum I’m capable with my current hardware and software).

In this review: Grain, resolution, sharpness. 400 megapixels from 35mm film. Dynamic range. Developing with Adotech IV. Scanning and editing. Manufacturing delay. How much does Adox CMS 20 II cost and where to buy it. Support this blog & get premium features with GOLD memberships!

¹ — A quote from the Adox website, which also states up to 800 l/mm resolution and 500 megapixels in each 35mm/full frame.

Grain, resolution, sharpness.

Regardless of the developer used, CMS 20 appears grain-free in all but the most detailed scans. On small screens and prints, it may be difficult to tell whether the photos were made with a modern high-resolution sensor or a product of an emulsion. However, this is still a physical medium, which means that close-ups may reveal some texture — a sign of dust or imperfect development techniques.

I also found that altering the exposure during post-processing may make those imperfections a little more visible. They may appear as tiny “bumps” or white dots in the darker areas. But there are ways to improve the quality of the negatives, one of which is using products such as Kodak Photo Flo and better control over temperature and drying environment.

If you’re looking to take full advantage of the CMS 20 II’s incredible resolution, consider using these techniques for making sharper images. You will also need a high-resolution scanning device. Since no commonly found digital camera can match this film’s rated resolution, you may have to opt for a drum scan.

Of course, there’s no need to blow your budget just to get more pixels out of this film. Adox CMS 20 II will yield silky-smooth, grain-free negatives regardless of the quality of your setup. Plus, there are ways to extract more image data out of the hardware you already have.

400 megapixels from 35mm film.

Nikon Super Coolscan 5000ED makes exceptionally sharp 4,000DPI scans from 35mm film. However, that’s nowhere close to the quoted 500-megapixel resolution. The best I can get with that setup is 21 megapixels.

I also have PrimeFilm XAs, which can produce an interpolated 10,000DPI — enough for 137-megapixel images. It’s much slower and has minor issues in its operation after years of service, but it’s still the best modern dedicated film scanner for 35mm film.

Scan interpolation uses software to partially fill in the gaps in data, though that’s still not nearly enough to get the most out of CMS II. Adobe has been shipping “Super Resolution” upscaling software for years that promises to quadruple the pixel count, which is another trick I used to upscale my scans. Though suboptimal if compared to an optical scan, I thought that a combination of all of the above techniques could meaningfully illustrate this film’s potential.

One last thing to note is that the negative I scanned using the above methods was developed in Ilford DD-X (which isn’t the recommended chemical for CMS II) and exposed with Voigtländer Vitessa A — a rangefinder made in the 1960s.

The results:

At 100% crop on a 13-inch high-pixel-density monitor, there’s no discernable grain, as expected. The file is 24,800 × 16,500 pixels, which translates into 10 image pixels for each physical display point on my Macbook Pro’s 2,560 × 1,600 Retina display.

At 25% crop, the file is a more manageable 6,200 × 4,125. Here, you may notice some texture but no individual grains. The resolution of this scan is still more than double that of my laptop’s display capacity.

After enlarging the image by a factor of eight, I’m not sure if there’s any more detail than when it was 4x. It’s hard to tell whether it’s because the interpolation and machine learning software failed to “fill in the blanks” or if it’s the film’s grain or, maybe, it’s my camera’s lens that limits this film’s true resolving power. But there are still plenty of pixels as this is 3,100 ×  2,063.

Finally, at 7% crop, you may recognize Adobe’s “fake” pixels. They look like tiny swatches of patterns stitched together.

A drum scanner or a darkroom print may reveal a lot more detail than this. Nevertheless, pretty impressive results. This is certainly more detail than I was able to capture on my PrimeFilm XA from any other emulsion.

If I were serious about printing Adox CMS 20 large, I would probably limit my scan to 4,000DPI with my Nikon Coolscan and take “Super Resolution” out of the equation. Even at that level, I should be able to make a two-feet-wide canvas (0.6m) at 300DPI, which is good enough to be viewed as close as 15 inches (38cm).

Dynamic range.

The extreme vignetting in the frame I blew up to 400MP (above) isn’t typical, even with the sixty-year-old film camera. It’s the result of the extreme contrast that CMS 20 II renders when developed in “normal” chemicals, such as Ilford DD-X. Thankfully, that photo was taken on a foggy day when the scene’s dynamic range matched that of the negative.

Scenes with more contrast can become unusable with this film. Adox suggests rating their film at EI 3 or 6 for a greater chance of success with typical developers — I shot it at 12. Still, only a few of the frames from that roll worked out.

Developing with Adotech IV.

Using the developer formulated specifically for this film makes a big difference for contrast control. With Adotech IV, CMS 20 II can be used as any normal black-and-white film without the need to select low-contrast scenes.

With Adotech IV, there are three choices for various film ratings: ISO 12, 20, and 25. The higher the rating, the more contrast.

The development times are nearly identical for all three ratings, with water temperature being the main difference: 23℃, 24℃, and 26℃, respectively. There are some slight differences in agitation; all dilutions are 1 part to 14 parts water, which translates to about 1.4L of developer or about five rolls of film from a single 100ml bottle.

For the longest time, I’ve been outsourcing film development to my local labs due to convenience, time, and space savings. They can take care of all the film types, including black-and-white. Yet none of them can develop with Adotech IV, which I think is essential for Adox CMS 20 II. So if there’s one film to convince anyone to start doing it at home, it’s this one.

Scanning and editing.

CMS 20 II, when developed with Adotech IV, is easy to scan. Thanks to its resolution, this film also responds well to contrast and brightness adjustments. Some emulsions, like Kodak Tri-X and Fujifilm Acros II, can become grainier with those adjustments, whereas CMS remains smooth no matter what you do. However, if you’re looking to print large, you should be mindful of slight imperfections during development which can become more visible when you increase the brightness of your scan; for those applications, I suggest you pay particular attention to your exposure and err on the side of overexposure.

Manufacturing delay.

A few North American retailers have marked Adox CMS 20 II as discontinued in 2024. However, the film is still in production. An unconfirmed rumour suggested that there’s a manufacturing delay due to the difficulties acquiring raw materials. Yet, the film is still sold at most European locations without disruptions. I’ve also contacted Adox directly, who have confirmed that the film is still in production and should be available worldwide.

How much does Adox CMS 20 II cost and where to buy it.

Due to shoddy availability, the film currently sells at a wide range of prices — from $13 to $33. It appears to be coming back to some locations; I will update this post once it becomes generally available and the prices settle.

❤ By the way: Please consider making your Adox CMS 20 II film and Adotech IV developer purchases using the links above  so that this website may get a small percentage of that sale — at no extra charge for you — thanks!