A 35mm film camera represented in Python object

[Lee Congdon]

Note also 36 exposure film.

 ------------------ Film -------------------------
    Speed:                      100 ISO
    Rewound into cartridge:     False
    Exposed frames:             0 (of 24)
    Ruined:                     False

On Sun, Mar 7, 2021 at 5:20 AM D.M. Procida <
real-not-anti-spam-address at apple-juice.co.uk> wrote:

> Hi everyone, I've created <https://github.com/evildmp/C-is-for-Camera> -
> a representation of a Canonet G-III QL17 in Python.
>
> There's also documentation: <https://c-is-for-camera.readthedocs.io>.
>
> It's a pure Python model of the physical sub-systems of a camera and
> their interactions. So far it's at a fairly high level - I haven't yet
> got down to the level of individual springs and levers yet.
>
> I spend quite a bit of my time repairing old cameras. To me they feel
> like computer programs encoded into physical objects, and figuring out
> how a mechanism works feels like working out how code works (but more
> fun).
>
> The Canonet G-III QL17 is one of my favourites. One of my reasons for
> writing this code is to appreciate the intricate mechanical logic
> embodied in the machine.
>
> You can do things like advance the film, release the shutter, meter the
> scene with the built-in light meter (if the camera has a battery of
> course) and even spoil your film if you make the mistake of opening the
> back in daylight.
>
>     >>> from camera import Camera
>     >>> c = Camera()
>
>     >>> c.state()
>     ================== Camera state =================
>
>     ------------------ Controls ---------------------
>     Selected speed:            1/120
>
>     ------------------ Mechanical -------------------
>     Back closed:               True
>     Lens cap on:               False
>     Film advance mechanism:    False
>     Frame counter:             0
>     Shutter cocked:            False
>     Shutter timer:             1/128 seconds
>     Iris aperture:             ƒ/16
>     Camera exposure settings:  15.0 EV
>
>     ------------------ Metering ---------------------
>     Light meter reading:        4096 cd/m^2
>     Exposure target:            15.0 EV
>     Mode:                       Shutter priority
>     Battery:                    1.44 V
>     Film speed:                 100 ISO
>
>     ------------------ Film -------------------------
>     Speed:                      100 ISO
>     Rewound into cartridge:     False
>     Exposed frames:             0 (of 24)
>     Ruined:                     False
>
>     ------------------ Environment ------------------
>     Scene luminosity:           4096 cd/m^2
>
>     >>> c.film_advance_mechanism.advance()
>     Cocking shutter
>     Cocked
>
>     >>> c.shutter.trip()
>     Shutter opens
>     Shutter closes
>     Shutter opened for 1/128 seconds
>     Shutter uncocked
>
> You can't do impossible things:
>
>     >>> c.shutter_speed = 1/33
>     Traceback (most recent call last):
>       File "<stdin>", line 1, in <module>
>       File "/Users/daniele/Repositories/camera/camera.py", line 29, in
>         shutter_speed
>         raise self.NonExistentShutterSpeed(f"Possible shutter speeds are
>           {possible_settings}")
>     camera.NonExistentShutterSpeed: Possible shutter speeds are 1/4,
>       1/8, 1/15, 1/30, 1/60, 1/120, 1/240, 1/500
>
> But you can also do things that you shouldn't do, like opening the back
> of the camera in daylight with a partially-exposed roll of film inside -
> which will spoil the film::
>
>     >>> c.back.open()
>     Opening back
>     Resetting frame counter to 0
>     'Film is ruined'
>
> I hope this interesting to someone.
>
> Daniele
> --
> https://mail.python.org/mailman/listinfo/python-list
>


-- 
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