I believe all but specialty cameras have an infrared blocking filter installed. They have this to eliminate the infrared that might be present in a scene and which would taint the color reproduction capability of the camera. Since the manufacturers don't know how much infrared the consumer will be shooting under they just choose to diminish the sensor's sensitivity to infrared. Most films (except infrared sensitive ones) did this automatically. When they do the conversion they replace the camera's infrared blocking filter with and infrared transmissive filter (but light blocking) and since the CMOS or CCD sensors are infrared sensitive you can expect significant increases in "speed". When you use the r87 with your current, unmodified, camera you are relying on capturing images by the residual infrared transmission of the infrared blocking filter in your camera. (Few filters are "perfect"). James explained this also in his own words. So now you have two of us saying the same thing in different words!! Andy On May 31, 2012, at 9:43 PM, Alberto Tirado wrote: >> Send your XT to LifePixel (www.lifepixel.com). They'll swap out your >> senser filter with an R87, or other specialty IR filter they sell. >> You'll then be able to shoot 1/400 @f8 AND look through your viewfinder. >> > > > This has me thinking ! > > If an r87 filter has a compensation of, say, 8 or 16 steps, how come you can convert your camera, in which they place an r87 filter on the sensor, and then go about happy-shooting? > My "reasoning" is that an r87 has a certain density, no matter if it is in front of the lens or behind it. > > > So how can you shoot at higher speeds with a camera conversion, but not with a filter? > > **************** > > Alberto Tirado >
