ColRay:
Thanks for the advice GoForSmoke. I'm not that electro savvy . I'm thinking best pay someome for a programm.
It's no fun then.
If you can build a pinhole camera, then you have the skills and ability to build an Arduino project that works a pinhole camera. The key to Arduino programming is doing it in bite sized chunks. Figure out each sub-system one at a time. For example, if this was my project, I would figure out how to reliably move a servo first. There are some examples built in to the IDE, in the Examples menu.
Once you do that put your servo to work in the shutter mechanism. Since the time is long, as you know, the shutter can just be something that blocks the hole for the closed position, and opens by simply by moving away. Old time photographers used their hat over the lens hole. So put the servo on a card that covers the hole in one position, and then rotates away, opening the shutter when exposure starts. Once the time for the exposure is over, the servo moves the card back over the hole.
This is the first part of your project. Write a program that moves a servo 90 degrees, then after some time, moves it back to 0 degrees. That is one exposure.
If you started your exploration of Arduino with the Blink sketch, as most of us did, you will be tempted to use the delay() function. Go ahead. It does exactly what you want. But don't fall in love with delay() for long, because it will turn on you once you want your program to do more than one simple thing.
ps, thanks for the link to your work - it's very cool!