Comparison dokko / Imacon

Below a comparison of a detail of a 35mm film scanned once with the dokko scanner and with an Imacon (which is the most common scanner currently in use) at various resolutions. The red area markes the enlarged detail.

Some footnotes:
  • the 3150ppi sample might look sharper then the 4000ppi sample on small screens because it's more pixelated.
  • the 6300ppi sample has about the same detail as the 8000ppi sample, this is due to the lens in the Imacon scanner being unable to resolve more than around 5500ppi.

Other Scan Systems

Some background information to the scanning methods commonly used by other scan services:

Imacon / Hasselblad

The Imacon 848 and 949 scanners (and the almost identical successor models Hasselblad X1 and X5) were considered the benchmark among film scanners when they were introduced in 2001. As a comparison, at that time Apple was still selling its egg shaped G3 iMacs with CRT screens and Nikon just released their top-end digital camera D1x with 5.3 Megapixel. Since then, digital technology has made huge advances, allowing for much higher image quality. Unfortunately, it has not been financially worthwhile for the established scanner manufacturers to develop new film scanners, so nearly every scan service still uses 20 year old technology.

As impressive as the devices were at the time, the Imacon scanners have several shortcomings that were massively improved on the dokko scanner:

Drum scanners

In the 1970s, drum scanners were marvels of modern technology and the first machines that could deliver good scan quality. They were considered unsurpassable until the turn of the millennium.

However, similar to Imacon, no new models have been developed for over 20 years, so the machines that are currently in use are all based on technology that is decades old and severely outdated.
Drum scanners are still advertised as giving the best dynamic range and noise performance, but the reality is that modern digital sensors and signal processing achieve significantly higher image quality than electronics designed 20 years ago.

Some Drum scanners claim resulution up to 12000ppi, but the true optical resolution tops out around 5000-6000ppi. They can still produce good results with larger film formats, where scan resolution doesn't have to be very high. On medium and small format film it becomes obvious, that their resolution is much lower than the advertised values. Drum scanners also have problems with getting accurate colors out of color negative film.

Their working principle requires the film to be wet-mounted, which means the originals have to be immersed in an oil or solvent liquid solution and glued into a drum using adhesive tape. This puts wear and tear on the original, accumulating dirt and scratches. There's also the risk of the film coming loose and getting damaged in a drum rotating at speeds of 2000rpm.
The dokko system was designed to work without any liquids, adhesive tape or rotating drum in order to keep the original in pristine condition and minimise the risk of film damage.

As mentioned, all the drum scanners still in use today were developed over 20, some even 30 years ago. Below an overview of some common models, including the year of their introduction:

Flatbed Scanners

High-end flatbed scanners can deliver very good results with large-format film originals, but with smaller formats their resolution is limited due to the optical system. Although they often advertise resolutions up to 6000ppi, their real optical resolution is about 2400ppi for the best prosumer levels and about 3000-4000ppi on the best high-end scanners. These are all machines from the turn of the century which means they are over twenty years old. Like drum scanners, they suffer from outdated sensors and electronics that are much noisier than modern digital components.

Widely used high-end models:

Frontier / Noritsu Minilab Scanner

Fuji Frontier and Noritsu scanners were developed to make fast, inexpensive preview scans and prints in minilab systems. They are commonly used to get an overview of all the images in a film.

These machines are also 20 years old and were tuned for speed and ease of use. The resulting images are unfortunately of rather poor quality, showing significant digital block artefacts and a restricted color palette. They are therefore only of limited use for further production and are no suitable digital backup for archiving.