ACST Shutter Tester

Why developping one more shutter speed tester ?

Finally I want to thanks Mr Condevaux-Lanloy for his precious help to define the bases of my shutter tester project.

What's new ?

> HIGHLY COMPACT and AUTONOMUS : Plug it to a standard 'micro-USB' mobile phone charger, it is highly portable and really tiny (60x35x20mm).

> SIMPLE : As the only concern for the photographer is the shutter accuracy for controled exposition, results displayed emphasis on the main usefull indication ; the Index of Lumination (IL) variation compared to the theory.

> VERSATILE : The tester include 3 sensors disposed in the 35mm format diagonal. In this way the tester provide the shutter speed in the center of the image but also the difference in the corners due to the start/stop of the shutter curtains.

> AFFORDABLE : The tester is designed to focus only on essentials features so that its simplicity would make a chance of a really affordable price in case of a marketing. The target is the price of a bundle of five Tri-X 120.

What are the detailed features ?

> When powered on, at first shutter release 'TEST01' the speed recorded in the center sensor (n°2) is used to define automatically the closest 'DIAL SPEED'. This 'DIAL SPEED' can get the following values : 1s, 1/2, 1/4, 1/8, 1/15, 1/30 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000, 1/8000

> The theoritical 'REFERENCE SPEED' is then computed in accordance with a '2 power' law : 1s, 1/2, 1/4, 1/8, 1/16, 1/32 1/64, 1/128, 1/256, 1/512, 1/1024, 1/2048, 1/4096, 1/8192

> The microcontroller display then the 'DIAL SPEED' + 'REFERENCE SPEED' + sensor 1 to 3 speeds with (IL) shifts relatives to the 'REFERENCE SPEED'

> Press the 'RESET' button to be ready for the 'TEST02' and release the shutter

> After 'TEST02' completed the results are displayed for sensors 1 to 3, the (IL) shifts relatives to the 'REFERENCE SPEED'of the first stored test 'TEST01'. When pressing the 'MODE' button you display cyclically : >> current 'TEST02' results >> averaged results for all the tests >> extreme results for all the tests >>

> Press the 'RESET' button to launch the 'TESTxx' procedure to get averaged and extreme results

> At any time, press 2x the 'RESET' button to change the reference shutter speed by restarting the 'TEST01' sequence 

When starting to restore and repair Rolleicord bodies I faced the necessity to develop some measurement and testing devices. In particular the final step of a shutter CLA require a shutter speed tester.
When looking around at the different available alternatives  nothing was really what I was looking for and the prices were not also compatible with my occasional usage.
Here and there I could find some DIY testers based on microcontroller but nothing was really achieved and adapted properly into a classic plastic enclosure. Nevertheless when going through these different developments I made my mind in which kind of hardware architecture and fonctionnalities I needed.

A first prototype have been developed within two weeks based on a classical 'Arduino' type microcontroller and has been fully checked and tested.
The second stage of marketing analysis is still in progress with the help of Corentin Van Praet and Léon Mari.