[Leica] IR filters

[imagist3 at mac.com (Lottermoser George)]

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