[Leica] Best Infrared filter for Noctilux??

[Michael Waldron <Michael@cadogan.net>]

While it might not be the highest in optical quality (which may not be the 
biggest issue, depending on the IR look you want -- Kodak IR is sort of 
blown out looking anyway) is to get a gel from B&H (I use Lee 4x4), 
probably about $15-20.  They come with a template for cutting into a 
circle, but if not, you can use the filter ring.  You can then get a 
cheaper UV filter with a retaining ring, take out the ring and the glass, 
put in the gel cut into a circle, then put the glass and ring back 
in.  This way the gel is on the inside for less flare.  I use an 87 opaque 
filter for IR because I want the maximum filtering of light.  However, this 
does make the film really slow (i.e. ASA 4-7 for nominally 100 Macophot IR 
film).