Features
- Single sensor (overal speed measurement)
- Accurate at up to 1/4000s
- Accurate with both focal plane and central shutters, from 35mm to large format.
- ISO-516:2019 compliance : the measurement method and performance are compliant with the shutter measurement ISO standard
- Easy to use
- Battery / USB powered
Optional light diffuser for central shutters
With focal plane shutters (SLR, telemetrics, …) the integrated LED can be used as a light source.
With central shutters, all the surface of the shutter is involved to enlight any single point of the image. So, to perform an accurate speed measurement of a central shutter, this surface must be enlighted evenly .
Be aware that most artificial lights exhibit a high-frequency oscillation, invisible to the human eye. This oscillation makes them unsuitable for speed measurement. The provided light sources (LED or optional light diffuser) meet the stability and homogeneity requirements to perform an accurate measure.
Why is the Baby Shutter Tester more accurate than other testers ?
The Baby Shutter thester is more accurate because it uses a different measurement method, a method that is
- Recommendent by ISO standard
- Also used by historical professional shutter tester, such as Kyoritsu shutter testers.
Measurement method: what to avoid
A naive method for measuring shutter speed is to start a timer when the amount of light that goes through the shutter exceeds a given threshold, and to stop the timer when the value falls bellow this threshold.
Such a method is used by all the cheap shutter tester currently present on the market. It may work fine at low speed, when the shutter can be considered as beeing perfect. But at high speed, the transition phases, when the shutter is not completely closed and not completely open, become predominant. Depending on the value of the threshold versus the light intensity, the measured speed value can be very different.
Furthermore, most of these cheap testers sport a 3mm size sensor. This size is to be compared with the slit between opening and closing curtains at 1/1000s, which is also 3mm large.
With central (leaf) shutter, the error is even worse, due to the optical characteristics of these shutters.
Because of this, the accuracy of these tester is usually less than 1 stop at 1/1000s. In other words, most of the testers cannot be used to test speeds above 1/250s, because they will give wrong or unreliable results.
Measurement method: the Baby Shutter Tester mark II
In order to measure the speed of a shutter, the Baby Shutter Tester takes into account all the light variations that hits its sensor. This is exactly what does a silver film: its takes into account all the amount of light.
This method allows the Baby Shutter Tester to take also into account the transition phases. So, even when these transition phases are predominant, the measure is accurate.
In addition, the Baby Shutter Tester Mark II meets all the recommendations of the ISO-516:2019 standard. Not only the testing method but also all the measurement accuracy requirements.
The benefits of this characteristics are the following:
- An extreme accuracy, at all speeds
- The accuracy is obtained without calibration procedure
- The accuracy is obtained whatever the type or the format of the shutter: focal plane or central (leaf) shutters, 35mm, medium format and even large format.
How is verified the accuracy of the Baby Shutter Tester mark II?
Two different verification methods are used:
- Graphic test method: the output of the analogic stage of the tester is displayed on an oscilloscope, and the signal width is compared with the displayed result of the tester
- Rotating wheel method: a wheel rotates at a known speed (3 m/s at the rim level), and a 3mm slit on the rim simulates a focal plane shutter at 1/1000s. The measurement result is compared with this expected 1/1000s value.