Re: [APML] a short note on film flat fielding

[Jerry Lodriguss <jerryapml@astropix.com>]

>However, I believe the effect of RF is taken into accout indirectly.
>All RF does is to modify the shape of the HD curve.  And such modification
>is a function of incident light strength, i.e., the illumination pattern.
>If all I did is to derive the fim response under certain illumination
>pattern, the effect of RF should be already included.

Hi Wei-Hao,

Didn't you say you were using daylight shots to model the flat 
fielding?  This isn't the same level of illumination as when the film would 
experience low-intensity reciprocity failure. With a short daylight 
exposure, you might not experience any LIRF at all anywhere in the frame. 
With an optimum exposure for a low intensity scene, the RF would change 
directly with the vignetting, wouldn't it?

Different films also have different HD curves. Wouldn't this be a reason to 
use the same film?




>So, in short, I just give up, forget about RF, and pray that RF is
>really a minor effect.

I don't think anyone has ever answered this question, but it would be great 
if you were right.

Your wonderful results certainly speak for themselves!

Jerry



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