Longer Wavelength Infrared Photography Using 850nm Filters
Most people who try infrared photography gravitate to the 720-nanometer IR filters, such as the Hoya R72. I thought I’d introduce you to some hard-core long-wavelength IR photography, using an 850nm filter.
The long-wavelength part of the light spectrum has some costs associated with it. First, you lose the ability to make false-colors; you’ll have to stick to black-and-white. Secondly, you have to brace yourself (and your camera) for some really long exposure times (typically 2 or 3 minutes in sunshine).
Black and white photos have a timeless quality to them that I have always loved. I don’t consider it a significant handicap to lose the ability to see colors in this range of the spectrum.
People are encouraged to avoid landscape photography around mid-day, mainly due to the harsh shadows. The exact opposite rule applies to infrared; mid-day is the perfect time to be taking pictures. I find that overcast conditions or being under a tree canopy generally makes for drab and lifeless IR photos. Forget about portraits; hardly anybody could possibly hold still long enough (this doesn’t apply to IR-converted cameras, however). It could be fun on the beach, though, to magically make everybody disappear.
Before I forget to mention it, these kinds of extreme exposure times will require you to cover up your viewfinder eyepiece. Such long exposures will let too much light leak inside your camera, so something similar to the Nikon DK-5 eyepiece cover or the eyepiece shutter (if your camera has one) is a requirement. Even well-built cameras leak a small amount of light through the eyepiece, but in most conditions it can be safely ignored.
I have an 82mm diameter 850nm IR filter, and I use my set of step-up rings (with every size from 49mm through 82mm) to enable attaching it to nearly every lens I own. My filter is made by BCI, but several companies make them. I'm not overly impressed with the BCI filter quality, but their price was good. I would suggest you find another company's IR filters for shorter wavelengths; the BCI 720nm didn't cut off enough red light.
You can’t see anything through the lens with the 850nm filter mounted, so you have to focus and compose first, and then attach the filter. Remember to either shift the focus according to the little IR focus dot on your lens (e.g. the really old Nikkor lenses), or else stop your lens down to at least f/8.
Assuming you’d like to view a ‘neutral’ picture on your camera’s LCD screen, you need to come up with a preset white balance. Your camera won’t be able to automatically measure a white balance preset, and you can’t set a low-enough Kelvin temperature, either. I have an article here that might enable you to get an approximate preset, although it doesn’t work with all cameras.
Please, please shoot in RAW format. This kind of photography is useless unless you do post-processing, and RAW formats will let you adjust your shot with the least collateral damage. If you’re unable to get a good white balance preset, RAW format will at least let you adjust the color balance in an editor after you take the shot.
I will typically use noise reduction, alter highlights, shadows, increase contrast, convert to black-and-white, and also apply an un-sharp mask to each photo. You will need to make extensive use of your camera’s histogram feedback to arrive at the desired exposure. A typical exposure for this filter in mid-day sunshine is ISO 400, f/8 and 2 to 3 minutes. I set the camera on “time” exposure, which is only available in manual exposure mode on most cameras. Make sure you have plenty of battery power.
Now, for the bad news. Most lenses are useless with infrared photography, even the expensive professional ones. The best lenses, in my experience, are the old manual-focus Nikkors; the ones that have the little red “infrared focus” dot on their focus scales. The lenses that don’t work for IR will get you a white blob in the middle of the photo. Surprisingly, a really good infrared-capable lens is the Nikkor (DX-only) 18-55 f/3.5-5.6 VR kit lens; infrared is the only thing I still use this lens for. Here’s a link to IR lens performance you will find handy (these guys also convert cameras into IR-only).
The long infrared light waves have super penetrating power. As a result, sky and water gets incredibly dark. This filter reminds me of the old Kodak infrared black-and-white film photos.
Your main enemy when shooting landscapes with this filter is wind. Every small branch and leaf will turn to mist. On the other hand, ocean and waterfall shots might just end up with a very nice effect.
Examples
Really dark skies and water, really long exposure. 18mm 154s f/10 ISO 400
You never know which plants will really glow in infrared
Wind can be your enemy with the long exposure times
The Light Spectrum
Our extraordinarily limited view of the universe
It’s amazing how little our eyes can see, compared to the range of light. Human vision stops at a little longer than 700nm, which explains the popularity of the 720nm filters (you get to see some IR, but exposure times are minimized). 850nm photography provides a glimpse into an otherwise-invisible realm. Light at this wavelength is so low in energy that it takes extremely long exposures to make our camera sensors sufficiently register it.
The other end of the light spectrum, ultraviolet and beyond, is unavailable to photography unless you use quartz lenses. Normal lens glass is opaque to ultraviolet. These UV lenses are rare and expensive. Contrary to what you might think, a UV filter blocks UV light and is the opposite of what you need for this kind of photography. Did you know that bees can see in ultraviolet?
Conclusion
The 850nm filter gets you a kind of “moonlight” effect. The sky loses the tobacco-color you get from shorter-wavelength IR filters, and your shots all tend to look like they were taken at night. Think of 720nm filters as “daytime” IR, and 850nm as “nighttime” IR.
You probably won’t want a steady diet of this kind of photography, but if you want dramatic landscapes, this filter delivers. You will see the world in a whole new light.
