Most digital photographers who go beyond simply taking a few snapshots encounter the question of whether to “shoot in raw” or work with the JPG images produced by most cameras. There are some excellent guides on the internet that explain the technical details behind this decision and offer balanced lists of pros and cons for you to consider. For me though, these articles seemed to say it was just a trade-off between quality and storage space. In terms of technical details that’s a fair assessment, but it’s only when this makes a significant difference to your photography that it actually matters.
When you take a picture with a digital camera, the sensor is exposed to light which produces a pattern of electrical signals that are read off by the camera electronics. This relates to the amount of red / blue / green light falling on each part of the sensor, and a bit of maths can convert the signal details into a picture. The maths needs some other inputs to convert the electrical signals into the coloured pixels making up the resulting image, and these take into account various details such as white balance, ISO, lens distortion and image enhancement features such as sharpening. The raw image format for your camera typically stores the direct readings from the camera sensor, plus the other settings at the time you took the photograph. The JPG image from your camera stores the resulting picture after the maths has been done – and for a common and fairly wide range of scenes it’ll look great.
The key difference here is that, provided that you have software that can replicate the raw -> JPG conversion that your camera can do (and in many cases this is actually possible on the camera itself), then you can re-run the conversion with other settings. For example, lighting conditions might have changed but you didn’t adjust the white balance on your camera, or maybe you underexposed an image in manual mode – no problem, you can simply go back and create a second rendering of the image using the raw data with adjusted settings for the correct white balance or effectively raising the ISO. That’s amazing – it means that you can worry less about your camera settings and more about photographing things that might never happen again.
Raw images typically also record more detail in the image (this is the quality factor) – often using 12-, 14-, or even 16-bits per colour per pixel, whereas most JPG output will be at 8-bits per colour per pixel. The most wonderful thing about this is that the extra detail recorded in very dark (or very light) parts of your image – whilst all but invisible to the human eye – can be used to recover detail using the Shadow and Highlight recovery tools in your photo processing software.
I use a Nikon D3300 which can give me the Nikon proprietary NEF (raw) format, and/or a JPG output. A common situation where I struggle with taking photographs is at stage performances. Anyone who has tried to photograph a school play will be familiar with the combination of low-level lighting, moving subjects, an awkward location to photograph from, and the pressure to come out with a photo that does justice to the performers (and the photographer). I like to ensure that the exposure is fast enough to avoid motion blur, but this often results in very dark images even with the largest aperture available, or sometimes I want to narrow the aperture to increase the depth of field. I also don’t want to use flash as it’s often the case that the ambient light is key to the mood of the image.
By using the raw format I can shoot with my desired exposure and aperture settings (often using manual mode and/or keeping the ISO low) bring the dark images down to my computer, run them through Shadow recovery (I use Adobe Lightroom – often the Auto Tone feature does 90% of the work for me) and adjust the sharpening a little, and then print or generate a JPG for uploading to Flickr. Sometimes a little bit of smoothing is needed to help reduce any noise that is inherent in low-light photography.
What started off looking like an almost completely black image ends up as a nice clear picture with the main subjects picked out in the ambient light – and any highlights aren’t blown out because I’ve used Shadow recovery rather than just increasing the overall exposure. Yes, my raw files are around 12MB where the JPGs were only 4MB, but at the rate I’m storing pictures it’s going to take several years to fill up my 2TB drive – so I’m happy to say “Hurrah for shooting in raw!”.