Archived posting to the Leica Users Group, 2007/02/05
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi Adam, Take a look at this site and this page in particular. <http://www.naturfotograf.com/UV_IR_rev03.html#top_page> He covers every aspect of IR and UV photography in great detail. Len On Feb 5, 2007, at 7:38 PM, Adam Bridge wrote: > I am sure hoping someone who is practicing IR photography can respond? > I'd also find the answer valuable. > > Adam > > On 2/3/07, Lottermoser George <imagist3@mac.com> wrote: >> Could some of you IR photographers please comment on comparison of: >> >> Dark Red 092 (89B) >> The nearly opaque B&W 46 mm Dark Red Infrared (092 = 89B) Filter, >> which looks dark purplish-red when held in front of a light source, >> blocks visible light up to 650 nm, and passes only 50% of the >> radiation just below 700 nm (thus the dark red color). From 730 nm to >> 2000 nm, transmission is greater than 90%; This makes photographs of >> pure red and infrared images possible with the best utilization of >> the relatively low sensitivity of infrared films As the sensitization >> of infrared black and white films barely extends beyond 1000 nm, the >> red portion that is transmitted still makes a relevant contribution >> to the exposure; That is why this filter is the preferred filter for >> pictorial photography on IR black and white film. >> >> and >> >> 093 (87C) >> Removes complete visible spectrum. This B&W 46 mm 093 (87C) Infrared >> Glass Filter blocks the entire visible spectrum, so to our eyes it >> looks completely opaque. Unlike the B&W 092 infrared filter, it makes >> pure infrared photographs possible without the visible red component. >> Its transmission only begins to exceed 1% at 800 nm, rising to 88% at >> 900 nm, and remains that high far beyond the upper limit of >> sensitization covered by infrared films. This filter is used less >> frequently in pictorial photography because of the dramatic loss of >> effective ISO. In the scientific field, materials research and >> forensics, the limitation to a strictly infrared range is often >> important. >> >> How do these descriptions translate into real world use (exposure, >> focus compensation, etc.) and relative "look" of IR images? >> >> TIA for helping me learn about this field. >> >> Regards, >> George Lottermoser >> george@imagist.com >> >> >> >> >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information