Evening.

Did not know which sub-forum this was best suited, but seeming as I guess it is an integral part of my development plan then yeah…it has ended up here.

I am making a timelapse rig that uses the canons remote port. My hardware fully works (light sensor included) but a bit stuck on the programming. Not the programming itself as such, but the maths on one part.

Basically, I have a starting value for the shutter speed (we will call it x).

x needs to increase to 2^y where y is a user defined value (in photography…the “stops”).

The increase needs to occur over a series of shots (s). Another user defined value.

So x = 2^y after s shots.

I do not want a linear progression…as in where the shutterspeed simply increases by the value of the curve’s gradient (y=mx+c) but I want a polynomial type? This is where my maths dies I am afraid!

I want the increase to be proportional to the shutter speed.

I wrote some basic code to “re-evaluate” the increase after say 10 shots were taken. This worked but gives a more “jagged” curve. What would be the relationship as an equation using x,y and s?

Thanks for any help! The curve looks kinda exponential but no idea how I would work it from first principles!

I have attached a print of my code outputting the values, except although it is “use-able” the code is a horrible mess so a simple equation for the relationship between the 3 variables would be great!

The image is where x=0.1 (starting shutter speed in seconds), y=10 (10 stops) and s = 130 (over 130 shots).