SIGMA have never been afraid to go against the grain, but there’s something unique about the Sigma SD Quattro that makes it perfect for infrared photography. Tim Shoebridge takes a closer look in this first article of a series of three that appeared in Black & white Photography magazine, including new images.
SHOOTING INFRARED by Tim Shoebridge
As a photographer with a career spanning 35 years, I have had the privilege and immense pleasure to use scores of different cameras. I was reflecting on this recently when considering the endless stream of new cameras that appear on the market each month. With so many cameras to choose from it is often hard to differentiate between them. But once in a while a camera does come along that stands out from the crowd and becomes one you want to pick up and turn to for inspiration.
For me, such a camera is the SD Quattro from Sigma. The SD Quattro is a remarkable camera in today’s market with a unique sensor and look to the images it captures. But there is one special feature to this camera that is not immediately obvious but is very important and is my chosen focus for this article.
Infrared photography dates back to the early 1900s and has for many decades been a creative outlet for film photographers. In the glory days of film cameras, infrared photography was very accessible, infrared-sensitive film was readily available, the development process was standard and pretty much all lenses had an infrared focus index mark on them.
‘The SD Quattro mirrorless camera is an absolute dream for infrared photography.’
It is only since we have embraced digital image capture that infrared photography has become harder to achieve. Ironically, the digital camera sensor itself is in fact highly sensitive to infrared radiation, so much so that captured images contain severe colour contamination. Manufacturers go to great lengths to produce the most accurate colours possible, and so must eliminate this contamination by fixing an IR blocking filter permanently over the sensor. Such a filter is called a hot mirror, since its semi mirrored surface reflects infrared radiation away from the sensor and helps to reduce heat build-up.
So if you want a digital camera that is sensitive to infrared radiation, it is standard practice for either you (if you are brave enough) or else a technician to perform major destructive surgery on your camera to remove the hot mirror and replace it with something else. Whatever it is replaced with, be it a filter for infrared photography or just clear protective film, will not be permanently fused on to the sensor and so is at risk of becoming a dust magnet. I have got through three infrared converted digital cameras over the years, all eventually became unusable because of trapped dust that is impossible to remove.
SIGMA has a reputation for bucking the trend in many aspects of camera design. One trend they have refused to follow is the permanent fixing of a hot mirror to their Foveon sensors. There may be a technical reason specific to Foveon sensors as to why they do not do this, but the result for us photographers is that their SD Quattro mirrorless camera is an absolute dream
for infrared photography.
Both the SD Quattro and SD Quattro H employ a removable hot mirror that sits just inside the mouth of the lens mount. If you are dexterous and have nimble fingers you can easily remove and refit this hot mirror without using any tools. For the rest of us, a simple pair of tweezers is all that’s needed. I have posted a short instructional video on my website on how to remove and refit the hot mirror, but on this page are some images from that video to help illustrate the process.
Click here for instruction video on the Sigma Lounge.
Once the hot mirror is removed, your SD Quattro is ready to shoot full spectrum colour images or infrared images with a suitable filter fitted to your lens. A mirrorless camera such as the SD Quattro takes all the guesswork out of obtaining accurate focus and exposure thanks to its live view and focus magnification both on the LCD screen and in the EVF.
Infrared photography can be a rewarding approach to a subject, and it can also provide opportunities for great images when natural lighting conditions would otherwise not yield good results with a traditional image capture.
Visit Tim’s website for more details; https://timshoebridge.photography/