Yes this Slide Direkt Rollei film looks fascinating. http://www.fotofenster.de/news/2006/09/rollei_retro_slide_50.html I am a bit puzzled by the physics and chemistry involved beyond this. Characteristic curves of this film can be found here : http://www.fotohuisrovo.nl/documentatie/RolleiSD.pdf I know that Kodak used to manufacture a direct copy film name Kodak Direct Duplicating Microfilm 2468 http://www.kodak.com/US/en/dpq/site/TKX/name/DuplicatingFilmsProduct and also #5360/7360 http://www.kodak.com/US/en/motion/products/curves/c5360.shtml and KODAK AEROGRAPHIC Direct Duplicating Film 2422 http://www.kodak.com/eknec/documents/f8/0900688a802b09f8/ti0573.pdf http://www.kodak.com/US/en/dpq/site/TKX/name/DuplicatingFilmsProduct I have no idea whether these films still exist but a direct positive slide is film is certainly not unheard of. The informations I had read were that the film used the solarization process, so the film was supposed to be pre-fogged and subsequent exposures would place it in the negative slope of the extended H&D curve. I had never found the explanation really satisfactory at least as far from I had seen from solarization curves which appeared like tiny bits of a negative slope after saturation. Something I would never imagine to be useable in the real world, except by Ansel Admas and his famous "black sun" image ;-) The characteristic curve of the new Rollei direct slide film seems so perfectly smooth and so linear (in log-log scale ;-) that it is really puzzling. Sure I would like to test it. 120 rolls are announced for April 2007 at a retail proce of 6.75 euros. Not cheap but definitely cheaper (even if you include some drops or rodinal and some drops of fixing bath) when compared to Scala film nd its dedicated professional process. Carlos Manuel mentions the extremely fine grain and high resolution of this supposed-to-be orthochromatic film. This is an excellent reason to re-visit our classics in silver halide photography ; I have always taken for granted that ortho film delivered a much better resolution than panchro film, simply by reading the specs, but to date I realize that I do not have a simple explanation why it is so. Why does red light sensitivity actually impairs the resolution of a film ? I have noticed for example that the FTM curve of a color film is not as good in the red layer as in the blue layer. Is it simply the more complex structure of a panchro film vs. an ortho film than degrades resolution ? or what else ?? I cannot imagine that it is only a question of wavelength-related diffraction effect, since 320 lp/mm are equivalent to a blur spot of about 3 microns, this is 4 times bigger than the limit wavelength of "actually visible" red light at about 750 nm. BTW although the sensitiviy of the human eye to visible light is suposed to be well-known at least since the 1931 CIE curve was published, I have found an excellent article giving more details : http://www.4colorvision.com/files/photopiceffic.htm -- Emmanuel BIGLER <bigler@xxxxxxxx> --- Rollei List - Post to rollei_list@xxxxxxxxxxxxx - Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe' in the subject field OR by logging into www.freelists.org - Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with 'unsubscribe' in the subject field OR by logging into www.freelists.org - Online, searchable archives are available at //www.freelists.org/archives/rollei_list