High-throughput film-densitometry: an efficient approach to generate large data sets

Abstract

A film-handling machine (robot) has been built which can, in conjunction with a commercially available film densitometer, exchange and digitize over 300 electron micrographs per day. Implementation of robotic film handling effectively eliminates the delay and tedium associated with digitizing images when data are initially recorded on photographic film. The modulation transfer function (MTF) of the commercially available densitometer is significantly worse than that of a high-end, scientific microdensitometer. Nevertheless, its signal-to-noise ratio (S/N) is quite excellent, allowing substantial restoration of the output to "near-to-perfect" performance. Due to the large area of the standard electron microscope film that can be digitized by the commercial densitometer (up to 10,000x13,680 pixels with an appropriately coded holder), automated film digitization offers a fast and inexpensive alternative to high-end CCD cameras as a means of acquiring large amounts of image data in electron microscopy.

Disulfide Linkage and Structure of Highly Stable Yeast-derived Virus-like Particles of Murine Polyomavirus

“…The cryo-EM images were recorded on Kodak SO-163 film at a magnification of ϫ38,000 using a Philipps CM 200 transmission electron microscope at 200 kV with defocus values of 1-1.5 m. Low dose conditions with an exposure of ϳ20 electrons/Å 2 per image were used. Images were digitized using the Nikon Super Coolscan 8000 ED densitometer (17). The images were scanned with a resolution of 6.35 m per pixel and later averaged 2-fold in each direction, resulting in a resolution of 3.34 Å/pixel at the sample level.…”

Cryoelectron Microscopy Map of Atadenovirus Reveals Cross-Genus Structural Differences from Human Adenovirus

“…Negatives were digitized with a Nikon super Coolscan (8000ED) using recommended settings (33). The data were then coarsened 2ϫ (Å/pixel ϭ 2.14).…”

Digitisation of electron microscope films: Six useful tests applied to three film scanners

“…The film is held in a glassless frame and the image must be focused (this is done automatically) each time to compensate for the fact that the film is not completely flat. Some users have modified the film holder to sandwich the film between two sheets of glass [12].…”

“…It is possible to measure relative XY magnification in other ways. For example, it would be possible to use any regular test grid or the method of Typke et al [12], which compares by cross-correlation two scans of the same micrograph before and after a 901 rotation of the film.…”