Leica US has loaned me an M8 for testing with infrared (see the diglloyd Guide to Digital Infrared Photography). As reported in Infrared Contamination: Good Color Gone Bad, the Leica M8 has a weak infrared-blocking filter installed (only a very thin filter is used so as to preserve lens performance) and so the M8 can do double duty without modification as an infrared camera.
I’ve had time only for a few test shots in infrared, using a B+W 092 filter (50% cutoff at 700nm). Exposure times are just barely adequate for handheld mid-day shooting at ISO 320. I generally prefer to permanently convert (modify) my cameras for infared use so as to achieve exposures of roughly 1/320 @ f/11 at ISO 100. However, converting a Leica M8 is an expensive proposition that few owners would consider undertaking without knowing the possible results. Over the next few weeks I’ll be reporting on the Leica M8 behavior in infrared, so check back regularly.
The M8 with a B+W 092 filter is 4-6 stops slower than a converted camera because it has internal infrared-blocking glass over the sensor. The light that gets through the combination of the B+W 092 and internal filter will be partly visible light (deep red), and partly infrared. More investigation will be needed to determine the proportions. Results so far indicate a moderate infrared effect, and with an unusually granular result which degrades sharpness considerably. Further investigation under controlled circumstances will help explain this phenomenon.
Leica M8 with B+W 092, 35/2.5 Elmarit
1/30 @ ~f/8 handheld, ISO 320