Hi Axel! > Lars, if this is a question to me--then yes, I did consider using an > ND filter, but no, I can't use one because the lens I'm using is a > 4.5mm fisheye lens that doesn't allow the use of filters, AFAIK.
Ok that sounds scary. Probably it would be possible to get a setup with a filter wheel behind the lens - but that would not be a small handy device to be carried around outdoors any more. For capturing a LED, there is no need for a fisheye though, so here one or more filters might be an option. Of course one would have a very close look at how "neutral" that density filter actually is. > Either way--you'd want to expose (much) longer than a full cycle which > is only 1/100 sec. This severely limits the range of exposure times > available for the HDR sequence. If I remember correctly, Santiago > Torres captured sunny skies in his PhD thesis, and he had to use two > identical cameras for this, one of which was fitted with an ND filter. > Aligning the two must have been a nightmare. Actually there are codes around doing the alignment by the use of shared keypoints. I mentioned Hugin before - I have not used it to get photometric values from images, but it claims to handle HDR formats, includes a lot of alignment functionality, and is free. Maybe worth to try it? Another question is how close two "identical" cameras can get... Cheers, Lars. _______________________________________________ HDRI mailing list [email protected] http://www.radiance-online.org/mailman/listinfo/hdri
