[Radiance-general] conversion of digital pictures to Radiance?

[Roland Schregle]

Greg Ward wrote:
> A minor correction to Rob's note -- you should actually fix the f-stop 
> and vary only the shutter speed in your exposures, not the other way 
> around.  The reason for this is that f-stops are not very reliable or 
> repeatable on most cameras, but shutter speed is reasonably sure.  Here 
> is an excerpt from the quickstart_pf.txt file that comes with Photosphere:

Another more fundamental reason is that f-stops affect depth of field 
and therefore the effect of focusing errors and lens aberrations. If you 
vary the aperture, your images may not be consisent in focus, 
particularly in near field photography. This course assumes the digicam 
implement f-stops traditionally with an actual diaphragm. If it simply 
modulates the CCD gain (as I believe most El Cheapo digicams tend to do) 
this is all moot anyway.


-- 
Roland Schregle
PhD candidate, Fraunhofer Institute for Solar Energy Systems
RADIANCE Photon Map page: www.ise.fhg.de/radiance/photon-map

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