MIRROR CENTERING AID
The mirror centering aid helps you to center the camera to the chart. This smart tool is very useful to give you the very best precise results.
1. Place the magnetic mirror on the center of the chart by using the 4 discreet magnets.
2. Place the camera at the rough required distance from the chart.
3. Frame the center of the lens reflexion in the mirror.
4. Doing this, the optical axis becomes perfectly perpendicular to the chart. Because you frame the center of the chart, the center is equidistant about its 4 corners.
5. Finally, adjust precisely the distance using the sliding plate.
Your test can begin !
The P.A.T. charts give you the possibility to check mathematically the resolution of your sensor or your lens.
For this mode, use the numbers of each circular and linear targets.
The numbers in the concentric and linear targets, in twentieth of a millimeter, express the number of pairs of lines printed on 1 mm
Adjust the position of the camera using the mirror centering aid.
The table beside gives you the correlation between the numbers in the concentric and linear targets, the number of pairs of lines printed on the chart on 1 millimeter and the number of pairs of lines printed on the ﬁlm or sensor on 1 millimeter.
To use this correlation table,
place the chart at a distance from the image plane 50 times the focal lengh of the lens to be tested.
Example for a 50 mm lens :
50 x 50 = 2500 mm = 2,5 meters = 8 feet
Analyse your lenses and print them with stop wide open.
The degree of sharpness depends on the clarity between the lines. The resolving power depends on the number of lines seen.
OPTICAL WEDGE SCALE
The optical wedge scale anables you to deﬁne at best the results of the sharpness test.
For exemple, if the ratio is 3, then -5 mm becomes -15 mm, -4 becomes -12 mm, etc..
Play your recording and ﬁnd easily the best result.
Analyse the picture frames with a microscope to ﬁnd the best result.