Canon's new entry-level EOS M50 is also the first Canon camera to come with the new Digic 8 processor, allowing it to capture smaller C-Raw files in the new CR3 format. The EOS M50 may be aimed at beginning photographers, but its all-new Digic 8 processor makes it Canon's first camera to use the CR3 Raw file format.
Older Canon's that used the CR2 file format could capture either uncompressed Raw files or 'medium' or 'small' equivalents, which saved you disk space at the expense of reducing resolution.
However, if you enable the compact 'C-Raw' option on the M50, the files will be 30-40% smaller than their uncompressed equivalents without any reduction in resolution. But are there any other image quality penalties to pay? Let's take a look.
Click here to download the original Raw files for all of the below comparisons.
Base ISO
Uncompressed Raw
Compressed Raw
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ISO 100 | 1/40 sec | F5. 6 | Canon EF 50mm F1. 4
The above images were shot and processed using our standard studio testing procedure. Do you see any differences? We couldn't find any - but we decided to see if boosting the ISO value and using our low-light scene would turn anything else up, particularly in terms of shadow noise.
High ISO
Uncompressed Raw
Compressed Raw
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ISO 12800 | 1/40 sec | F5. 6 | Canon EF 50mm F1. 4
Now that we've switched to our low light setup and boosted the ISO by seven stops, the images still appear all but identical, even in terms of noise levels. So far, it looks like it's best for you to go ahead and switch into C-Raw and save yourself some disk space.
But when we put the EOS M50 through our standard exposure latitude test, we did find some evidence of what sort of processing is happening in Canon's C-Raw files.
Pushed shadows
Uncompressed Raw
Compressed Raw
Image pushed four stops in Adobe Camera Raw
Our exposure latitude test involves exposing our studio scene with increasingly lower exposures, and then pushing them back to the correct brightness in Adobe Camera Raw. With many older sensors, you would see an abundance of noise being added by the camera, but today's sensors output files that are much more tolerant to this sort of manipulation.
Basically, after pushing the files, we look into the shadow regions to assess the exposure latitude (essentially the dynamic range) of the Raw files. And it's after underexposing the EOS M50 by four stops and then re-brightening, we start to see some clearer differences between the regular Raw files and their C-Raw equivalents.
The resulting pattern can be more difficult to remove or reduce than normal noise patterns, and is reminiscent of artifacts left behind from noise reduction algorithms that we've seen in the past.
At this time, we're optimistic that users of Canon's new Raw format can shoot in C-Raw without a noticeable impact on image quality.
But after all, this is a four-stop push. Depending on your shooting, this may indicate a slight dynamic range disadvantage to using C-Raw, but it's likely to remain an edge case for most users. And so we've decided to finish off with a more informal test in a more common situation. We wanted to see if processing out the two different Raw files would turn up different results for the gradient in a blue sky.
Blue skies and takeaways
Uncompressed Raw
Compressed Raw
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ISO 100 | 1/640 sec | F8 | Canon EF-M 15-45mm F3. 5-5. 6
Smooth gradients can often trip up compression algorithms, particularly in many cameras' JPEG engines, so we wanted to see if there was any noticeable difference when the EOS M50 compresses its Raw files. As with our un-pushed studio images, it's again impossible to tell which is the normal Raw file, and which is the C-Raw file. So what does this all mean?
Of course, we still have plenty of tests to run on the EOS M50, but at this time we're optimistic that users of Canon's new Raw format can safely shoot in C-Raw and save themselves valuable memory card and disk space without noticeable impact on image quality.
Note that all of the above images of our studio scene were processed in an identical manner to images in our studio scene widget, meaning there was no sharpening nor noise reduction added. Adjustments for the blue sky scene were limited to highlights, shadows, whites and blacks in Adobe Camera Raw, and sharpening and noise reduction were left to default levels.
Click here to download the original Raw files for all of the below comparisons, and to see how the EOS M50's uncompressed Raw files compare to its peers, check it out in our studio test scene.
. dpreview.com2018-4-2 16:00
