TECHNICAL INFORMATIONS

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 !

SHARPNESS TEST

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.

Write the informations about the lens on test in the corresponding areas : brand, serial number, focal, stop.
Place the camera from the P.A.T. chart at the distance advocated by the optical wedge sheet (approximately 50 times the focal lengh of the lens).
Stick the center of a self-adhesive graph paper on the engraving fixed mark of the lens.
Write in the «ratio» area the ratio corresponding to the lens. the ratio depends on the gap between focus engravings. It has to be multiplied with the measurement unit of the scale (mm).
Millimeter is the measurement unit of the scale. It goes from -5 mm to + 5 mm and corresponds to the variation of the lens ring in the minus or in the plus directions around the correct testing distance of the lens.
For exemple, if the ratio is 3, then -5 mm becomes -15 mm, -4 becomes -12 mm, etc..
Write in the «eye» area (useful for camera films to calibrate the viewfinder) the best focus reading.
Using your watersoluble pen, circle the number corresponding to the variation distance of the adjusting ring of the optical lens. Start with -5. Record or print a few frames (2 or 3 seconds). Erase the circle marker writing -5, circle -4, move the ring of the lens to -4 mm, record a few seconds. Do this until +5. You will get an approximately 30 seconds movie.

DIGITAL CAMERAS

Play your recording and find easily the best result.

FILM CAMERAS

Analyse the picture frames with a microscope to find the best result.