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THE NATIONAL BUREAU OF STANDARDS RESOLUTION TEST 
CHART OF 1952 
by 
Francis E. Washer 
National Bureau of Standards, Washington, D.C. 
The Optical Instruments Section of the National Bureau of Standards has 
been using photographic resolution tests as a routine procedure in evaluating 
the image forming abilities of photographic objectives. These tests were initiated 
because it was believed that the quantitative results of measurements of resolu 
tion in the image were of more practical 
value to the users of lenses than the results 
of measurement of such quantities as coma, 
longitudinal spherical aberration, curvative 
of field, and other aberrations. This belief 
has been justified by the success of the 
charts throughout the years. At least, those 
instances have been so infrequent as to be 
practically nonexistent when a lens which 
showed poor performance in a resolution 
test was later found to be yielding excellent 
images of natural objects. 
The resolution test chart, shown in 
figure 1, used in the precision lens testing 
camera 1 ) was a high contrast transparency 
consisting of patterns of black lines on a 
clear background. A range of resolving 
power in the image plane of the lens under 
test extended from 3.5 to 56 lines/mm in 
nine steps forming a geometric progression 
with the ratio between two successive terms 
approximately equal to the square root of 2. 
Because of the interest expressed by 
amateur photographers, (particularly those 
having miniature cameras using 35 mm film 
whose negatives required considerable en 
largement for proper viewing) in a simple 
test that could readily be performed by an 
individual, it was decided to make this resolving power chart available to the 
public. The NBS Circular C428 entitled “A Test of Lens Resolution for the 
Photographer” was prepared by Dr. Irvine C. Gardner and was published in 
early 1941 * 2 ). 
NATIONAL BUREAU|0F STANDARDS 
TEST CHART I 25 X 
Figure 1. 
High contrast resolution test 
chart formerly used. 
This chart formed a part of NBS 
Circular C 428. The ratio of the 
line spacings in successive pat 
terns of this chart is equal to V 2. 
When the chart is photographed 
at the standard distance of 26f, 
the values of resolving power 
that can be measured with this 
chart range from 3.5 to 56 lines/ 
mm. 
*) Precision camera for testing lenses. I. C. Gardner and F. A. Case, J. Research NBS 18, 449 
(1937) RP 984. 
2 ) A test of lens resolution for the photographer. I. C. Gardner, NBS Circular C428 (1941).