A 35mm film camera represented in Python object

[Mike Dewhirst]

On 2/04/2021 8:47 am, D.M. Procida wrote:
> 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'm now working on the exposure system, which in the published version
> so far just models inputs and outputs of the system as a whole. I want
> to start to model its functionality by modelling the interactions of its
> components - the levers, cams and so on.
>
> It seems to me I have fundamentally two approaches that I could take:
>
> The first is to model the movement of each lever as a series of discrete
> steps (hundreds of tiny steps, to maintain accuracy). Pro: it models
> movement through physical positions; con: it's ugly that it breaks
> continuous movement into arbitrary steps.

If in doubt model the real world.

>
> The second is not to move each lever in such detail, but to consider its
> interactions: given the state of each of the other parts of the system,
> what *would* be the outcome if something were to try to move the lever
> from such-and-such a position to another? Pro: it feels more elegant
> than the brute-force stepping of the alternative; con: it also feels
> like a bit of a cheat.

Usually taking shortcuts means losing information. You can only drop 
intermediate data which doesn't trigger other events.

Go with your instinct

>
> But neither approach really captures for me the interaction of moving
> analog components, which in the case of this camera also have some
> circular logic to them - the movement of A determines that of B which
> determines that of C which determines that of D which finally also
> affects the movement of A.

Connect things which are connected and recalculate A in passive mode.

>
> Any thoughts or wise ideas?

May the force be with you

>
> Daniele


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