An advantage of replacing Canon's
IR Cut filter with a coated clear glass window is that add-on
IR PASS filters can be used for infrared imaging. The following
infrared images were taken using the popular infrared "Hoya
R72" filter. In bright light the camera's autofocus works
to some degree. Since the infrared HOYA R72 filter is mounted
on the camera lens, mostly infrared light is being directed to
the autofocus (AF) sensors at the base of the camera. A diagram
of the light path can be seen HERE.
Although the diagram is for a Nikon DSLR, it is applicable to
the Canon DSLRs. The viewfinder image will be dark with the infrared
filter attached so focusing manually through the viewfinder is
not possible. Precise focus is best achieved by trial and error
using the camera LCD display. Camera lenses need to be "short
focused" a little to achieve focus with infrared light as
compared to normal light. Some camera lenses have "red"
focus shift markings for infrared. I have noted where my wide
angle zoom lens focuses best for infrared at infinity, and use
that setting for scenic daytime infrared images.
A color correcting filter, the
"X-NiteCC1 (IR Blocking) Filter" by maxmax.com was used
for normal daylight images.
The following images are "mouseover
images". You will need to have scripting allowed in your
web browser for this to work. Move your mouse cursor over the
image and you will see the normal image of the same scene. Move
the mouse cursor off the image to go back to the infrared image:
on and off image:
Imaging in infrared results in
clear sky appearing dark and vegetation such as grass and tree
blossoms appearing bright (white). Infrared cuts through sky haze.
The following summer scenes are not mouseover images:
For more daytime infrared images CLICK
To learn more about Infrared Imaging
with a Digital Camera, see the Digital Photography For What
It's Worth article:
Infrared (IR) Basics
for Digital PhotographersCapturing the Unseen