Archived posting to the Leica Users Group, 2001/08/01
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Thanks very much, Henning. I'd already ordered the B+H 093 (87c), but will now also get the B+H 092 (89b). Probably I'll also try some strips of gel filter taped to a pinhole bodycap... Cheers, G. On 1 Aug 2001, at 10:17, Henning Wulff wrote: > At 9:57 PM -0400 7/31/01, George Kenney wrote: > >Thanks much, Marty. > > > >I had this discussion this evening with my photo workshop > >instructor, who was unfamiliar with the effects of an 87C (because he > >works with SLR in 35 and 120). He tried to steer me to a 25A filter, > >but I pointed out that with a rangefinder the blackness of an 87C is > >not an issue. > > > >Anywho, thanks for your constructive comments. > > > >G. > > > >On 1 Aug 2001, at 10:11, Marty Deveney wrote: > > > >> For all the IR info you'll ever need refer to: > >> > >> http://www.a1.nl/phomepag/markerink/mainpage.htm > >> > >> Note that you can buy 120 / 220 Kodak infrared cut down from 70mm > >> aerial stock: http://www.homestead.com/infrared/ > >> > >> None of the other medium format films are as sensitive to IR light > >> as Kodak IR film. > >> > >> Also note that the 87-series filters are opaque and MUCh darker > >> than the red filters. Rangefinders are perfect for working with > >> IR film and an 87 series filter because you can see and shoot at > >> the same time. Much better than composing, putting the filter on, > >> locking the mirror up . . . yawn . . . > >> > >> Marty > >> > >> > > Using an 87c, even with HIE, is kind of pushing it. The exposure times > are extremely long, and the effect is quite similiar to the 87. The > 87c has only 3% trasmittance at 800nm, while the 87 has 57%. As the 87 > is essentially opaque below 750nm, it is probably the best choice for > HIE. The other commonly available IR films will not work with the 87c > at all, as their sensitivity in not far enough into the IR. The 87 > will work with the Maco, but the 89b is probably the best one. The > Konica will work with the 89b as well, although I like the results > with the 70 best. The 70 has a cutoff at about 660nm, the 89b at about > 690nm, while the 29's cutoff is at 610 and the 25's at 590, all at > approximately 5% diffuse density. > > If you want to get just one IR filter, the 89b is probably the most > useful. If you will only be using HIE, the 87 is probably the best > bet. The 87c is mostly useful for experimentation, and stay away from > the 87a (cutoff above 900nm). > > Regarding a previous question about loading HIE in the dark, YES, keep > it dim...., very dim. Tech Pan can be loaded in all but sunlight, but > HIE can fog with a 40w bulb in a fairly large room. > > -- > * Henning J. Wulff > /|\ Wulff Photography & Design > /###\ mailto:henningw@archiphoto.com > |[ ]| http://www.archiphoto.com >