Magnification Series from JEOL 1010 Recorded
Using the Gatan MegaScan 794 CCD Camera

Here are example images of a replica diffration grating (aka a waffle grid) that can be used to calibrate the magnifications for a camera like the MegaScan 794 on the JEOL JEM 1010. This sort of calibration is based on measuring distances between the known spacings between the lines shown in such images, and measuring the distance between multiple lines can reduce the uncertainty in the exact position of each line.

The EMC staff was able to calibrate the magnifications for this camera on the 1010 up to a magnification of 12000x using the waffle grid, but images at higher magnifications show less than a full grid square and can not be used for calibration. Magnifications lower than 100x do not show the waffle pattern clearly enough to use for calibration, though it would be possible to use the spacing between grid bars for that purpose at such low magnifications. It is also possible to use such a series of images to determine the changes in rotation as the magnification is changed.

NOTE: Even though the nominal magnifications of the mag mode and the low mag mode ranges overlap, these images clearly show that mag mode 1000x and 600x are significantly different from low mag mode 1000x and 600x (blue and red labels, respectively, in the table below)

Mag Mode: 5000x Mag Mode: 4000x Mag Mode: 3000x
Mag Mode: 2500x Mag Mode: 2000x Mag Mode: 1500x
Mag Mode: 1200x Mag Mode: 1000x Mag Mode: 750x
Mag Mode: 600x Low Mag Mode: 1000x Low Mag Mode: 800x
Low Mag Mode: 600x Low Mag Mode: 500x Low Mag Mode: 400x
Low Mag Mode: 300x Low Mag Mode: 250x Low Mag Mode: 200x
 
Low Mag Mode: 150x Low Mag Mode: 100x

These images of negatively stained catalase crystals were used to calibrate magnifications larger than 12000x (up to 100,000x) and to check that magnifications as low as 5000x were accurate.

NOTE: Such calibrations use the distance of diffraction maxima from the origin of the Fourier transform of each image, and assumes that the thin catalase crystals have crystalline lattice constants that are constant and well known. The lattice constants can change depending upon the sample preparation (reported values for negatively stained crystals are different from those for glucose embedded crystals which are in turn different from frozen, hydrated crystals. This again highlights the fact that all magnifications reported by electron microscopes are only approximations, and that when exact magnifications and pixel sizes must be known, the only solution is to include some sort of internal standard in the sample.

Mag Mode: 5000x Mag Mode: 6000x Mag Mode: 7500x
Mag Mode: 10000x Mag Mode: 12000x Mag Mode: 15000x
Mag Mode: 20000x Mag Mode: 25000x Mag Mode: 30000x
Mag Mode: 40000x Mag Mode: 50000x Mag Mode: 60000x
Mag Mode: 75000x Mag Mode: 100000x