Shutter Tester Application Notes
The shutter tester application has 3 global controls and 5 screens.
The global controls are at the bottom of the screen:
- switches captures of shutter events on and off. When off, Not Monitoring Tester, no new events are captured. When on, Monitoring Tester, all new capture data is propagated to the programs controlling the 5 screens. Each screen interprets the data according to its own needs.
- Monitoring Tester
Automatic Speed Select - when new data is captured and Automatic Speed Select is checked, the program makes an effort to automatically select the closest speed and enters the data in that row. When Automatic Speed Select is checked, the Calibrate screen will automatically jump to the next step. When Manual Speed Select is checked, the user must use the radio buttons on the screen to select the row where the next data is to be entered.
Calibrate Enable - when Calibrate Enable is selected data from the Calibrate page or from saved calibration information is used to adjust displayed datas values. Actual data is always maintained in memory and on disk when saving the results to disk. To view the actual data, select Calibrate Disable.
Each Screen Provides Different Interpretation of Captured Data:
- Provides exposure time and shutter speeds for focal plane shutters in milliseconds. The shutter speeds are time required for shutter to traverse between the two sensors. Actual shutter speed depends on distance between sensors for your particular sensor design.
- Provides exposure time in fractions of a second. For example 716 is equal to 1/716 of a second. At speeds slower than 1/30 of a second, it would be preferable to use the Speeds display because of rounding error. The shutter speeds data is the same as that of the speeds screen.
- Ratio between the best case result and actual. For example if the optimal result is 1/1000 and the actual is 1/750, 1/1000/1/750 = 1.33. This shows over exposure by 1/3 stop at that speed. The shutter speeds display is( actual shutter speed *2)/13.75 and probably should be ignored.
- Keeps track of up to the last 4 captures for each speed. The displayed value is the difference between the smallest and largest of these last 4 captures in milliseconds. Reading a saved file is equivalent to making a new capture. This allows you to track changes in your cameras perfomance over time. Simply capture shutter performance and then save the file. Later on when you test the camera again, first read the old data, then test the camera or visa versa. The stability screen will give you the difference between the old performance and the new performance. Reading several old files is equivalent to making several captures. You also may want to read and save the settings before tuning up the camera and again afterward to see the changes in performance that you have effected.
Calibrate - This screen is used to set up calibration data. Calibration data is only significant to displayed data when the Calibrate enable radio button is selected. Each sensor you construct may have slightly different behaviors, especially in regard to sensitivity of left and right sensors. By comparing responses from a normally positioned sensor and a reversed sensor, the program can adjust displayed values automatically. Also an overall adjustment can be manually entered that will affect both left and right readings. Calibratation data is saved whenever the current shutter data is saved. Once calibrated, make sure that you position the sensor consistantly in the non-reversed position when using it. Once data is entered click on the Calibrate button in order to calulate the difference in sensitivity between the left and right sensors. Use the Automatic Speed Select button in order to automatiically cycle through the stages of calibration. When Manual Speed Select is set, you can either select the appropriate radio buttons or use the Next Step button in order to move through the stages of calibration. When the Calibrate Enable radio button is selected, the reversed version of each speed displays the calibration effect, instead of the reversed speed captured by the camera.