Archived posting to the Leica Users Group, 2000/02/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 7:15 AM -0600 2/12/00, George Huczek wrote: >At 11:20 PM 11/02/2000 -0800, Jim wrote: >>I have some questions. I bought some Konica Infrared film to play with. Has >>anyone out there used this film? If so, what sort of ISO does it have? 25? >>50? and what did you soup it in? D-76 1:1? Rodinal? <snip> >> B&W infrared is sensitive to the blue region of the spectrum, >> and has been sensitized to the far red and infrared regions. >> To avoid getting a photo with nearly the same tones as Tri-X, >> a filter should be used to block the blue region, and transmit >> IR. The most commonly used filter is the red separation >> filter (#25, #25A, "A" or #29 deep red)... orange doesn't work >> as well. A slightly better filter is the nearly opaque #70 >> deep red filter, or the visually opaque IR filters of the 87 >> series (87C most common). B&W uses different designations. I would strongly suggest not trying the 87C with the Konica film, as its sensitivity is minimal in that region. Going beyond the 29 is not that useful, as you already need additional exposure with that filter. The spectral sensitivity of HIE makes the use of the 87C very useful, with only the loss of about one stop of exposure, but the Konica film's sensitivity goes down quickly after 750nm (therefore the name), and the 87C only has a transmittance of 1% at 760nm. The Konica 750 film is only marginally an infrared film and only slightly better than the Ilford SFX in this regard. In other words, if you can't see through the filter, the Konica film won't do a whole lot better. Other developer starting points are: D-76 @ 5.5 minutes, 1:1 @ 8 minutes, HC 110 Dil.B @ 6.5 minutes, all at 70 deg. F. * Henning J. Wulff /|\ Wulff Photography & Design /###\ mailto:henningw@archiphoto.com |[ ]| http://www.archiphoto.com