Digital Infrared Photographs with the Nikon D100 and D200

 

For several years now, I have been dabbling with infrared photography, primarily using Kodak HIE film.  My efforts have been somewhat limited due to the amount of work involved with shooting this kind of film.  Keeping the film refrigerated is nothing new, but loading the film into the camera in the dark was a unique experience.  Even with years of darkroom processing behind me, loading in the dark was tricky.   Plus, the need to carry another camera body meant that I rarely took it along.  I usually made special outings where my intent was to take infrared photographs, with results that were most often forced and disappointing.

 

Maple Tree, September 2003

This year, I renewed my efforts to make infrared images when I found out that my Nikon D100 was capable of infrared photography.  From my research on the internet, I was not completely certain that the D100 would be able to do this, but it seemed likely given good results from other Nikon digital cameras.    I decided to take the plunge, and try it out.

 

Some of the results of my efforts can be found on the Infrared Landscapes page.

 

Of the many benefits of digital cameras, one of the most liberating is the ability to change "film" in "mid-roll".   Rather than carrying different types of film, and different camera bodies, you can change ISO sensitivity, colour balance, and other settings on the fly.  This flexibility is what makes digital infrared photography so accessible now, compared to the past.

 

Equipment

The only extra equipment needed for digital infrared photography is an infrared filter.  Different types of infrared filters differ only in which wavelengths of light is filtered out, and which wavelengths are allowed to pass.   Visible wavelengths are from about 400nm to 700nm; above 700 is near-infrared, below 400 is ultraviolet.  The standard measuring sticks are the Kodak Wratten filters.  A Wratten 89B filter allows wavelengths above 720 to pass, allowing only a small amount of visible, deep red light to pass through.  Wratten 87 and 87C filters allow wavelengths above 800nm to pass, deeper into the near-infrared; they allow no visible light through. 

 

I use a Hoya R72 filter -- about the cheapest infrared filter on the market, and I've been very happy with the results.  The Hoya R72 filter blocks light below 720 nm (hence the name of the filter), and allows near-infrared light through, making it similar to a Kodak Wratten 89B filter.  The R72 filter is very dark, letting only a small amount of visible light through; holding it up to a bright light, you can see a faint deep-red image.  Hoya also makes the RM90 filter, which filters out light below 900nm -- deeper in the infrared than the R72, but it requires even longer exposures.

 

There are other filters out there -- Kodak Wratten gelatin filters, Tiffen 87 and B+W 092 and 093 filters.  Kodak  Wratten filters are thin films, and although smaller sheets are quite inexpensive, they are too flimsy for field use.    Tiffen and B+W make 89B and 87 or 87C Wratten-equivalent filters, but they were priced at least $20 more than the Hoya filter.  Price made my choice obvious.

 

Basic Technique

The technique for making an infrared image is quite straightforward.  Although I will describe this in terms of the D100, other cameras will have similar issues and solutions.

 

The first step is to compose your photograph, using a tripod, and with no filters attached.  The filter is almost completely opaque, so composition and focus must be done beforehand.  You must then screw the filter on without altering your lens focus or zoom settings -- sometimes a tricky business.   The tripod is necessary to hold the camera in place to attach the filter, and to allow you to make very long exposures -- possibly several seconds in length.

 

Pine needles and roots, September 2003

 

Focus can be an issue with infrared, since infrared light focuses at a slightly different spot than visible light.  Older lenses had a red spot or the letter R (in red) that indicated how to adjust focus for infrared, however, my more recent lenses don't have this feature.  The red spot indicated that you have to focus closer than with visible light -- for example, for a 7 foot object, you would focus at about 5 feet (of course, this is very approximate).  To avoid this problem, I usually stop down the lens to f/11 to f/22.

 

The next step is to set the ISO to 1600 or higher.   The filter is so dark, that even at 1600, I have to use very slow shutter speeds to make an image, especially using f/11 to f/22.  Of course, photographing with bright sun helps, but don't limit yourself to bright sun conditions.  The example here was taken during an overcast day.

 

I've tried Nikon's highest ISO settings, HI-1 and HI-2, which are supposed to be ISO 3200 and 6400 with high noise levels.  However, I did not find these to be particularly effective -- I usually got a darker image than expected.  ISO 1600, however, is quite effective, and only produces a moderate level of noise.  In fact, the noise I get is considerably less than the grain from B&W infrared film.  You may want more grain to simulate film, so go ahead and use HI-1 or HI-2 if you want.  

 

On the other hand, if you want less grain, you can always use lower ISO values, and use a longer shutter speed.

 

Raw image with Hoya R72 filter, f/16, 20 seconds, exposure comp +3.3.

 

To make a proper exposure, I have found that I have to use exposure compensation of anywhere between +1 and +3.  Typically, I use +1 when the sun is bright, and higher adjustments when the sun is behind clouds.  Fortunately, you can use the histogram to check the image out, and make immediate adjustments.  Don't be fooled by the look of the image on the LCD.  Use the histogram to make sure that the exposure is balanced appropriately.   No more guessing exposures and wide bracketing so necessary with infrared film!  

 

Lastly, I use the camera's RAW format.  I want to use as much image information during processing as possible, and this is accomplished with RAW format.  

 

The final tip before tripping the shutter is to cover the viewfinder.  Stray light coming in the viewfinder can significantly alter the exposure.

 

Post processing

The final steps are done in the computer.  First, you must create a black-and-white image for processing.  When I convert from RAW to TIFF, I use 16-bit depth (48 bits total), to preserve as much image information as possible.  Then, I convert to black-and-white.  I haven't found any conversion that's better than any other, so I just set Saturation to 0.  After using this method, the image is usually very dull, with virtually no contrast.  

 

Image converted to grayscale.

 

This is where the 16-bit conversion comes to play.  I use quite drastic adjustments to brightness and contrast to get the image that I want.  The extra bit depth gives me enough leeway to make the adjustment work.

 

I've also used Channel Mixer to do the conversion, and with various settings, I achieve similar results.

 

Pine needles and roots, final version.

 

Final note

In my work with infrared to date, it's clear that not every image or situation is suitable for infrared photographs.  An infrared image still has to be a good photograph -- the composition, focus, and exposure all have to work to make an effective image.  Infrared is just another tool to use, albeit a tool with quite unique properties in how light is interpreted.  I'm thrilled to have this tool available in the digital world, without all of the difficulties of infrared film.

 

Update: the Nikon D200 and infrared

Sadly for infrared photography, the Nikon D200 has significantly less infrared sensitivity than the D100.  The D200 requires much more exposure to create a usable infrared image.  In situations where the D100 would require a couple of seconds, the D200 requires more than 30 seconds to produce an image.  So, while it's not impossible to use the D200, it is much harder.

 

Links

There are a number of infrared websites, which provide a host of technical information about the subject.  Here are some useful sites:

http://www.irleague.com/Site/Home.html: The league of Creative Infrared Photographers

http://www.naturfotograf.com/index2.html: lots of information on infrared and UV photography

http://www.cliffshade.com/dpfwiw/ir.htm: Infrared basics for digital photographers

http://www.cocam.co.uk/CoCamWS/Infrared/INFRARED.HTM: Infrared FAQ

http://home.twcny.rr.com/scho/newpics/galleries.html: A nice set of infrared photographs

http://www.smudgeonmylens.com/galleries/IR/irgallery.php: Good infrared photographs

http:www.dimagemaker.com/specials/digital-infrared/digital-ir.php: Lots of infrared photographs, equipment reviews and information.

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