Exposure mapping

[polka]

Hi Peter,

I plotted the same curves with "my favourite grapher" and something does not feel right with the geometric blurring : yours begins at x=0, but with a non zero pinhole plane thickness it should not. However, what causes this difference, I find it not so obvious as the log base two affair ?

It would be nice that you send me the source code to let me see it ; I will give you my Email address in a private message.

Paul Attached files

[polka]

To conclude this discussion, let me group here the links to the four javascripts that Peter coded, with some comments. I verified that these tools strictly conform to my models, so if someone ought to be blamed, it's me. And they are really pleasing for playing at will with the design parameters of pinhole cams, so thank you and bravo Peter (aka durian).

To make design decisions with classic flat plane pinhole cams :

This first tool draws light fall-off in EV at x in mm, away from the center of the picture , where you may adjust with three sliders
- f the distance of the pinhole to the center of the film plane
- d the diameter of the pinhole
- e the thickness of the pinhole plate

This second tool draws four curves for blurring in mm, with two causes (geometric, meanning confusion circles, and diffractive, meaning...) in two directions (radial, meaning away from the center, and tangential, meaning perpendicular to the former), where you may adjust with four sliders
- w the wavelength
--- and the three parameters of the first tool

The two following tools are analog to the above tools, but instead, they are suited for anamorph cams :

This third tool draws light fall-off in EV at x in mm along a generatrix of the film forming cylinder, away from the pinhole plane, where you may adjust with three sliders
- f the radius of the film forming cylinder
- d the diameter of the pinhole
- e the thickness of the pinhole plate
This light fall-off is given with reference to the the hypothetical f/stop at the center of a flat plane cam with same f and same d. The maximum of this curve is at about -1.5EV under this !

Finally, this fourth tool draws four curves for blurring in mm at x in mm (same as in the third tool), with the same two causes as in the second tool, but with slightly different meaning of radial => transversal (from edge to edge of the film) and tangential => longitudinal (along the film band), where you may adjust with four sliders
- w the wavelength
--- and the three parameters of the third tool

Paul

[durian]

I noticed the graph plotting website I made had gone offline. I have now fixed it, and it is available at http://durian.org/pinhole/

-peter

[JoeVanCleave]

Nice, I’ll have to bookmark your site for future reference.