Infra-red

A comment on one of my infrared photos lead me to buying a new IR filter, an 87C, until now I have been using a Hoya R72. Although the R72 is a true infrared filter it's at the very short end of the IR band and partly allows very deep red light through as well. In fact if you look through it and exclude all other light you can see a very dim deep red world. The 87C is further down the spectrum and you really can't see a thing thought he filter with the naked eye, you can just make out the sun, which of course is not wise but I'm just giving you an idea of how dark it is.

Here is an example of the results, these were taken with a Canon 20D, the exposures are very long due to the IR filter in front of the sensor, it's there to filter out IR so the filter on the front of the lens is doing the opposite.

This is the scene in "normal" light (no filters)

Details: Walpole Park, Ealing
24/10/04 16:15
Canon 20D, ISO-100, RAW
1/250 sec @ f8
20-35mm 2.8L @ 29mm
Tripod

Infra-red through a 87C filter

Details: Walpole Park, Ealing
24/10/04 16:17
Canon 20D, ISO-100, RAW
120 secs @ f2.8 with B+W 093 (87C) IR filter
20-35mm 2.8L @ 29mm
Tripod

Infra-red though a Hoya R72 filter in false colour (red channel replaced with blue and change to the hue)

Details: Walpole Park, Ealing
24/10/04 16:22
Canon 20D, ISO-100, RAW
60 secs @ f2.8 with Hoya R72 filter (post processed see above)
20-35mm 2.8L @ 29mm
Tripod