INFRA RED

I use an old D1X coverted to accept ir and uv by having its factorry fitted Low Pass Filter replaced with a quartz plate. Here are all my bodies the D1x can be seen top right. Any lens will pass IR but it focuses at a different point than visible light. Often there is a red dot on the lens barrel to show the offset needed for ir focus. Thus focus in visible on manual focus add the IR filter to the lens once focused (they are opaque to visible light) . Adjust the focus by the required amount. Leave on manual focus so the lens doesn't hunt when the shutter is pressed slightly and so undo your focussing efforts. Also used, if not using sunlight, is the IR/UV flash gun - unfortunately these are no longer available from Nikon but most flash guns give out ir.

In order to record an ir image the visible light must be excluded I use either a Hoya R72 or RM90 filter whish pass ir above 720nm and 900nm respectively.

Normal meters do not respond linearly to IR so I have built a device to get around this problem

here is an IR photo rendered in black an white The RM90 was used.

Kodak Extachrome IR film had three layers of emulsion. One sensitive to IR, one to Red and one to Green light repectively. By taking an image 1st through an IR filter then red filter then green filter and combining them in photoshop this film can be emulated. It has the property that if vegetation is photographed like this healthy appears Red, stressed appears Yellow and Dead or Dying Blue. A visble light and image taken as above are shown here

Infra red light penetrates mist/fog as the longer wavelength is not reflected so easily as the shorter visible light wavelength so it can be useful to see through a mist. I am waiting for a foggy day to demonstrate this.             HOME