dynax/maxxum 5 shutter speed test [ no question:o) ]

I just tested my dynax 5 for the accuracy of shutter speed. Hereby i

gladly share the results.

<p>Method:

<br>no lens on camera body, low-power HeNe laboratory laser, focussed

on amplified silicon detector, 100MHz HP storage oscilloscope.

Recording the pulse-shape signal on the scope that shows up on the

monitor while the shutter is open. Measuring FWHM of this trapezoidal

pulse with the scope's cursors.

<p>The error of the measurements in the case of fast speeds is

slightly larger, due to the ill-defined rising and falling edge of

the pulse. These edges seem to be the same for all shutter speeds in

absolute values: ~50 microseconds, and are related to the movement

speed of the certain shutter leafs. However, at the fast end, since

the whole open-shutter time is shorter, the relative error becomes

larger.

<br>The time while the shutter is open and light can hit the film

<i>in one certain point</i> (the so-called shutter speed)is

measurable by measuring the flat top of the pulse trapezoids.

<p>Results for the shutter speed:

<br>___Set speed ______________Measured speed_____relative difference

<br>_____ 30s________________________34.0s___________13.0%______

<br>_____ 20s________________________22.5s___________12.5%______

<br>_____ 15s________________________16.3s____________8.7%______

<br>_____ 10s________________________11.0s___________10.0%______

<br>______ 8s_________________________8.5s____________6.3%______

<br>______ 4s_________________________4.1s____________2.5%______

<br>______ 2s_________________________2.0s______________0%_______

<br>[between 2s, and1/500s, unmeasurably close values.]

<br>_____1/500s_____________________1/520s____________4.0%______

<br>____1/1000s____________________1/1040s____________4.0%______

<br>____1/2000s____________________1/2090s____________4.5%______

<br>____1/4000s____________________1/4040s____________1.0%______

<p>As expected, the only real deviations from the set values show up

at slow shutter speeds - however, I'm quite happy to see that the

largest error is around 1/10th of an f-stop.

<p>

I plan to do more tests, such as shutter lag time, frames/second

speed, and diafragma accuracy for the lenses I own. Any

ideas/comments welcome.