(220) 
This circular contains two sheets of six high contrast test charts which can 
be cut apart to form 12 individual resolution charts. Each chart is printed in 
black ink on high grade white glossy paper. The master plate used in the print 
ing process was prepared by the Bureau of Printing and Engraving thus insur 
ing a high degree of accuracy in the line spacing and reproducibility of the 
charts. The size of the paper charts is such that when placed 26 focal lengths in 
Figure 2. 
High contrast resolution test chart. 
The ratio of the line spacings in 
adjacent groups is equal to ~V 2; 
however, the ratio of the line spac 
ings of corresponding opposite patt 
erns is 2. Consequently when this 
chart is photographed at the stan 
dard distance of 26f, the values of 
resolving power that can be measu 
red range from 12 to 80 lines/mm in 
a geometric series proceeding by]T"2 
Figure 3. 
Low contrast resolution test chart. 
The metrical characteristics of this chart 
are identical with those of the high con 
trast chart shown in figure 2. The con 
trast (ratio of reflection densities) be 
tween the gray ink of the lines and the 
gray background is approximately 0.26. 
The contrast between lines and spaces in 
this target is more nearly like that in 
natural objects than is that in the high 
contrast target. 
front of the taking camera, the image will be identical in size and metrical 
characteristics with that obtained when the lens is tested on the Bureau pre 
cision lens testing camera. 
Complete instructions accompany the charts which enable the amateur to 
perform the test with a minimum of equipment and technical experience. This 
chart has been very favorably received and upwards of 8000 copies of the 
circular containing the charts have been sold. 
Since this chart was first published there have been many advances in photo 
graphic technique, and lens resolution has been the subject of numerous inves 
tigations. As a result, many suggestions have been received dealing with impro 
vements to the chart. Consequently, it was decided to develop a chart incor 
porating so far as possible many of the suggested improvements. 
This chart has been made and will shortly be published as part of the NBS