What is Drum Scanning?

A drum scanner works very differently from a flatbed or conventional film scanner. The film is mounted directly to the surface of a clear acrylic drum, which rotates during the scan. A highly focused optical system reads the film as the drum turns, building the image with exceptional precision.

The Howtek 4500 uses photomultiplier tubes (PMTs) rather than the CCD or CMOS imaging sensors found in most film scanners. PMTs are extremely sensitive light detectors capable of measuring very small differences in the amount of light transmitted through the film. This is particularly valuable with dense transparencies and images containing a wide range of densities.

The Howtek can scan at optical resolutions up to 4000 DPI and accommodates film from 35mm through 8×10.

Resolution alone isn’t what makes a good drum scan. The real advantage comes from the combination of resolution, sensitive PMT detection, precise optics, wet mounting and the control the scanner gives me over how the film is reproduced.

Wet Mounting

Before scanning, the film is mounted to the acrylic drum using optical mounting fluid and a clear overlay. This holds the film flat against the drum and creates a more continuous optical path for the light during scanning.

Wet mounting can also make fine scratches and other minor surface imperfections substantially less apparent by reducing the way they scatter light. Unlike digital dust removal or software retouching, this happens optically during the scanning process itself.

Wet mounting requires considerably more preparation than placing film into a conventional holder, but it’s an important part of getting the most from a drum scanner. Every Drum Scan I make is wet-mounted.

Film Grain and Scanning Aperture

The Howtek gives me a degree of control over how the grain structure of the film is reproduced. By selecting different scanning apertures, I can change the balance between maximum resolving power and the prominence of grain in the finished scan.

A smaller aperture can be used when maximum fine-detail resolution is the priority, while a larger aperture can produce a smoother rendering of grain in colour negative and black-and-white films. This is an optical characteristic of the scan itself rather than software grain reduction applied afterward.

This can be particularly useful with faster or naturally grainier films, where reproducing the grain structure at maximum sharpness won’t necessarily produce the most pleasing scan.

Scanning the Complete Frame

Unlike the Flextight, the Howtek doesn’t require a film holder surrounding the image area. The film is mounted directly to the drum, allowing me to capture the complete exposed image and, when desired, the surrounding film rebate and edge markings.

This is particularly useful for photographs composed very close to the edge of the frame, images where no cropping is desired, or when you simply want the physical border of the film included in the final scan.

A Faithful Reproduction

The goal of a Drum Scan is to capture as much of the information present on the film as possible and reproduce it faithfully in the digital file.

I don’t apply sharpening during scanning, so detail isn’t artificially enhanced as part of the capture process. The aim is to produce a strong master file that preserves what I’ve captured from the film and leaves plenty of room for further editing.

Scans are produced using a colour-managed workflow. For more information about scanner profiling, colour spaces and how I handle different types of film, see Colour Management →

Flextight or Drum?

The Flextight Scan is the simpler and less expensive option while still producing an excellent file. A Drum Scan takes considerably more preparation, but it’s the option I choose when getting everything possible from the film is the priority.

For a detailed comparison of the two processes, see Flextight vs. Drum Scanning →

Learn more about Flextight Scanning →