Reducing the size
Free up more space on your memory cards
In addition to giving you a choice of image size and quality when shooting JPEGS, many EOS cameras also offer a choice of sizes when shooting Raw files. Not only does that mean you can squeeze many more images onto a memory card, it also gives you a higher maximum burst rate when shooting continuously.
The options available to you vary according to the camera you’re using, and whether it saves Raw images as .CR2 files or the newer .CR3 file type. The majority of Canon’s DSLRS record .CR2 files. As well as giving you a full-fat Raw, which is saved at the sensor’s max resolution, many of these camera’s also have M-raw and S-raw options which use fewer pixels to make up the image. For example, the 7D Mark II’S Raw images are made up of 20 million pixels, while M-raw and S-raw are recorded at reduced resolutions of 11 million and 5 million respectively.
Using fewer pixels has its drawbacks. It gives you less room for manoeuvre when it comes to to cropping images, and you’ll have to print photos out at a smaller size. That being said, you can still process the image as if it was a full-size Raw file in your editing software of choice.
Cameras that shoot .CR3 Raw files take a different approach and give you two options: Raw, or the more compact C-raw. Unlike M-raw and S-raw, the resolution of a C-raw file isn’t reduced to order to save space. Instead, the full-size file is compressed by discarding some of the image information. This type of ‘lossy’ compression can introduce artefacts and reduce image quality, but it’s usually very hard to spot defects unless you’re scrutinizing an image at a very high magnification.