Infrared photography: Oslo at 760+ nm

Infrared photography is fascinating. It takes some skill to imagine what objects will look like after the camera filters out the visible light, and (often) we turn the saturation slider to a minimum.

I have been thinking of a post (or a series) dedicated to infrared photography. I will start with some examples that I have taken using a 760 nm filter on a camera whose IR-cut filter has been removed from the sensor.

To clarify succinctly, silicon sensors are quite sensitive to near-infrared light, i.e., light that is "a bit redder" than red. Our eyes' limit lies at about 700-720 nm. I can see some dim objects through my 720 nm filter, but it might be leakage of red light. On the other hand, sensors can see up to 1000 nm.

In order to capture photos that are similar to what we normally see, manufacturers put infrared-cut filters to diminish the infrared light that passes through the sensor. Some cameras can be disassembled sufficiently easily at home (at your own risk!) and the IR-cut filter removed. The camera is then capable of seeing into the infrared region, as well as somewhat into the ultraviolet range, hence it is called a multispectral camera.

Infrared-pass filters block light that is shorter than a particular wavelength. Often these are 720 nm and 760 nm, though there are 830 nm and even 950 nm filters. I took the photos below while exploring the capital of Norway, Oslo, with my camera equipped with a 760 nm infrared-pass filter.

The Akershus fortress dates back to the 14th century.

In my opinion, it is best observed from water. There are many boats that take you to the nearby islands. At departure, it is possible to see and admire the beauty of the fortress.

A closer view right at departure from the Aker Brygge area in the heart of the capital.

Next comes Rådhuset which translates as the red house. This huge majestic brick building is actually the city hall.

Another time I will share colour photos.

The photos and the story are (or will be) posted on my other social platforms, too.