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so since my camera saves my photos automatically in JPEG and since I wanted to have a RAW version of them I looked for some info about this topic and how it works on my DSLR, Canon 77D. I stumbled upon an article where I found this little scheme, which confused me a lot cause I don't get why I can store more pictures saving both files instead of just the RAW files. If someone can explain me this, I'd be very grateful! enter image description here

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  • \$\begingroup\$ vtc b/c No real question to answer. The chart simply has a mistake. \$\endgroup\$
    – xiota
    Oct 19, 2018 at 18:38

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It looks like the value for only RAW files should have been 270 instead of 170. Multiplying the average file size given by the corresponding shot count yields values between approximately 7GB and 8GB for all entries except RAW. 170 images at 29.4MB would be about 5GB, 270 images would be about 8GB. The file size given for RAW+JPEG is quite close to the sum of those for RAW and JPEG Large/Fine, so the file sizes can be assumed to be correct. So, seems like an actual error in the table.

Correction: After checking the full specification available at https://downloads.canon.com/nw/camera/products/eos/77d/specifications/canon-eos-77d-specifications-chart.pdf (table is on page 7), the numbers for RAW and RAW/JPEG have simply been swapped. The numbers according to Canon are 210 for RAW and 170 for RAW/JPEG.

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    \$\begingroup\$ OK, now I'm really confused. Because your "uncorrected" answer made perfect sense: 8000MB divided by 37MB per shot gives about 216 shots in RAW+JPEG, and 8000/29.4=272 in RAW. Though all the cases where there are more than 1000 shots on the card seem to claim about 10% fewer shots than you'd expect from dividing card size by file size. I'm confuuuuused. \$\endgroup\$
    – David Richerby
    Oct 19, 2018 at 16:26
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    \$\begingroup\$ Admittedly that surprised me as well. It could be, that the file size given is an expected average, while the number of possible shots is more conservative, i.e. can be almost always expected to be possible even for larger than average files. I don't really know, though. \$\endgroup\$
    – ad42
    Oct 19, 2018 at 16:31
  • \$\begingroup\$ -1 for the "correction". Looked at the PDF, and it has the same mistake as the table OP posted. Values were not swapped. \$\endgroup\$
    – xiota
    Oct 19, 2018 at 19:04
  • \$\begingroup\$ @xiota The question is essentially "Why is the number of possible RAW shots unexpectedly smaller than for RAW+JPEG in this table." The PDF file has the two numbers reversed, which makes them consistent, albeit relatively low, for both settings (slightly more than 6GB total in both cases). Some of the other entries also have total sizes below 7GB on an 8GB card, although not quite as low. How Canon actually arrives at these values is a completely different question, as is what the most accurate estimate would be. \$\endgroup\$
    – ad42
    Oct 19, 2018 at 19:46
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  1. The table has a mistake, as you pointed out.
  2. Numbers of "shots" are just estimates to give you an idea of the relative differences in file size.

  3. You should have been able to – Do the math yourself.

    >>> 8000/37.   # RAW + JPEG
216.21621621621622
>>> 8000/29.4  # RAW
272.108843537415

  4. Don't believe everything you read.

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