I’ve been somewhat interested in trying infrared photography for some time. However, in my reading about it, it seemed as if there were only three ways of getting into it.
So what is a person to do if they’d like to see if they like infrared, but don’t want to pay a lot of money in case they don’t.
Well, it turns out that there is a fourth option, and that takes us back to the camera in the preceding post (See: Another newly acquired old camera: Sony F828). The final line in that post includes the sentence: “But there’s something very special, even unique about this camera”.
One particularly interesting feature that was introduced in the the earlier DSC-F707 which made it into the DSC-F828, is what Sony called “Night Shot” which was an infrared technology borrowed from their higher end camcorders. Night shot (and the similar “Night Framing” modes) rely on both an IR emitter on the front of the camera, and the ability for a visible light filter that is normally placed in front of the digital camera sensor to swivel out of the way. To better understand Sony’s Night Shot feature, you need to know a little more about how digital camera sensors and the human eye perceive light.
In high school science class, you may remember that light travels as a wave. Light is all around us in a variety of wavelengths, some the human eye can see, some that it can’t. A wave consists of peaks and troughs. The distance between two peaks or two troughs is called the wavelength. As the wavelength changes, the properties of the light change as well.
For most people, the human eye can detect light with a wavelength of between 380 and 750 nanometers (there are 1 million nanometers in a millimeter). We perceive light between these two wavelengths as color, with violet on the low end and red on the high end. Beyond the visible spectrum of light on the low end is ultra-violet light, and on the high end is infrared. Light beyond the visible spectrum is around us all the time, we just cannot see it, at least not without help.
As the wavelength of visible light changes, the eye perceives it as color. Image courtesy, lightcolourvision.com.
All digital camera sensors made back then and today, can detect a wider spectrum of light that can see beyond what the human eye can see, from about 350 to 1000 nanometers. While the difference on the low end between 350 nm and 380 nm is small and would have little effect on the sensor’s performance, the difference on the high end from the 750 nm limit of the human eye to the 1000 nm limit of the sensor, is a problem.
All digital cameras have a visible light filter in front of the image sensor that blocks unwanted IR and UV light from being detected by the sensor.
In order to more closely match the spectrum that the human eye can see to what a digital sensor can see, all digital cameras have a visible light filter applied over the sensor to restrict the light that passes through it. Without this filter, digital sensors would be taking in more information than is needed, which would change the look of the images that the camera displays.
Cameras with Sony’s Night Shot feature have that same filter over the sensor to block unwanted wavelengths, however unlike most other digital cameras, that filter is on a hinge and can be electronically controlled by the camera for special purpose photography. Combined with an IR emitter on the front of the camera, which is essentially a flashlight that only emits IR which our eyes (and filtered digital sensors) cannot see, when used together, the visible light filter moves out of the way, allowing the sensor to see the full spectrum of light, including the IR light being projected from the front of the camera. Since the human eye cannot see this light, but the camera can, the sensor is able to focus on the IR light in complete darkness.
Sony uses this feature in two different ways. In the main Night Shot mode, IR light is emitted by the camera, the visible light filter moves out of the way, and the camera takes pictures of just the IR light in complete darkness. Although IR light cannot be seen by the human eye, the sensor can now see it, and it stores these images with the IR light changed to green, giving that “night vision” look that is often associated with electronic night vision devices. Although Night Shot images are presented in green monochrome without any other colors, they are an effective way of photographing objects such as sleeping babies in complete darkness.
A second Night Framing mode starts out the same way, using the IR emitted to shine light over a dark scene, and the visible light filter moves out of the way so that the digital sensor can focus and meter for whatever you are attempting to photograph, but at the moment of exposure, the IR emitter turns off, the visible light filter moves back in front of the sensor, and the camera fires it’s flash and shutter to capture a normal flash image in full color of objects in complete or very low light.
For anyone whose ever attempted to take photographs in complete darkness, you’ve likely encountered difficulties with the camera being able to focus on and meter for the extremely dark scenes. Even modern digital cameras and smartphone cameras today still struggle in very low light as they simply cannot “see” objects in complete darkness. With Night Framing mode, the camera uses it’s Night Shot technology to focus and meter for your shot, but then makes a normal flash exposure using the information it obtained using the IR light.
The Sony CyberShot DSC-F828 would be Sony’s last camera in the series and the last with the Night Shot feature. A combination of some scandalous uses of the feature, plus a widespread misunderstanding of the technology caused it’s removal in future models. By the mid 2000s, DSLRs had gained much more popularity as did more traditionally styled point and shoot’s so an oddly shaped top of the line camera with a $1000 price tag likely caused it to sell poorly.
Sony would never release a camera with the Night Shot feature again, and to the best of my knowledge, no other camera maker did either meaning these features are unique among this family of cameras in that they could do something that the best cameras today can’t.
When attaching an external magnet to a specific location in this area of the camera, you can override the built in visible light filter and move it out of the way, turning the DSC-F828 into a full spectrum camera.
I could probably end this review here, talking about a neat camera with a strange design and some cool features and that would make for a pretty interesting look back, but I’d be leaving out one more unintentional feature.
When Sony designed the visible light filter that could be moved out of the way of the digital sensor, they controlled it with magnets. At some point, some clever owners of these cameras discovered that if you used a small and powerful magnet, and attached it to the camera in a specific location, you could manually move the filter out of the way, essentially turning the camera into a full spectrum digital camera.
Now, you might be thinking, why would anyone want to do this? I thought you said that the reason these filters exist in the first place is to filter out light we can’t see, and that by including that light, we’d have undesirable images?
Using a magnet to manually disable the digital sensor’s filter, you can shoot the camera in full spectrum mode, that when used with a screw on IR filter, allows you to shoot infrared photographs in daylight.
That is true, however by eliminating the filter and exposing the sensor to the full 350 nm to 1000 nm spectrum, you can use screw on filters to pick and choose which wavelengths you want the sensor to see. Since we know that IR light is around us all the time but we can’t see it, by using a full spectrum digital sensor and a screw on IR filter, you can turn the camera into an IR only camera, something Sony never designed the camera to do. When used as intended, the Night Shot mode limits the aperture and shutter speed to only specific settings to optimize low light photography. With the camera in it’s “normal” mode, but the visible light filter out of the way, the camera doesn’t have these limitations, allowing you a full spectrum of f/stops and shutter speeds, while still shooting IR photos.
Shooting a full spectrum digital camera with an IR filter in bright sunlight will produce images with otherworldly colors. Lush green trees will turn white, blues and reds will take on a purple or sometimes yellow hue. By mixing different color filters and some clever post processing, you can make your local nature park look like an alien landscape.
There is a small niche of digital photographers who will open up their cameras and permanently remove the IR filter that is permanently attached to their sensor to achieve this effect. But once these cameras are modified, they are not easily returned to normal, meaning they will only work in IR mode. Furthermore, most cameras that are modified this way are usually point and shoots as they’re the easiest to work with.
With the Sony DSC-F828 and the two models that came before it, swapping back and forth between full spectrum and normal mode is just as simple as attaching and removing a magnet. You can change back and forth as often as you like with no damage to the camera!
Today, because of this ability, plus it’s excellent f/2 Carl Zeiss lens, 8 megapixel sensor, ability to write RAW files, and it’s screw on filter mount which makes using IR filters very easy, the Sony DSC-F828 has developed a bit of a cult following for IR photographers. These cameras are one of the easiest entry points into IR photography, and for those times you want to turn the feature off, you still have a pretty good regular digital camera.
So I got the magnet and some inexpensive Infrared filters and off I went to try this setup out.
The results of my efforts will follow in the next few posts.
