Archived posting to the Leica Users Group, 2002/10/03
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Paul, IR film is sensitive to the full spectrum of visible light, not just infrared. The visible spectrum stops at somewhere around 700 nm. Ilford SFX and Konica IR are sensitive up to 750 nm, Maco 820 up to 820 nm (surprise) and Kodak HIE up to 900 nm. But in all cases the films are also sensitive to visible light, so you need to use an appropriate filter, otherwise the visible light will overwhelm the infrared. These filters cut out visible light wavelengths to varying degrees. The Heliopan filters are conveniently named, so that for example the 695 filter cuts out all light below 695 nm etc. Nathan Paul Hardy Carter wrote: > Mark, > > Thanks for that. Only question is, why bother with the SFX filter when the film is only going to react to IR anyway? I could understand that the SFX would give you a near IR look on a panchromatic film, but with film that is only sensitive to IR it seems like belt and braces. Or is it just to slow the film down? > > - PHC > -- > To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html > > - -- Nathan Wajsman Herrliberg (ZH), Switzerland e-mail: wajsman@webshuttle.ch mobile: +41 78 732 1430 Photo-A-Week: http://www.wajsman.com/indexpaw2002.htm General photo site: http://www.wajsman.com/index.htm - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html