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Raw and JPG file sizes - E-M1 and GX7

Discussion in 'Accessories' started by bassman, Aug 26, 2014.

  1. bassman

    bassman Mu-43 Top Veteran

    678
    Apr 22, 2013
    New Jersey
    Scott
    I was lost another SD card yesterday when one of the plastic splines between the contacts broke. I have a long trip, including a photography workshop, coming up, so I started looking at new cards. I though it would be prudent to actually check how big the image files are for the two bodies I'll have with me, the E-M1 and GX7. I always shoot Raw+JPG (Large/Fine) in 4:3 format. Here's what I found by looking at my actual image files, which seems strange to me:

    E-M1
    - Raw: ~15MB (manual says 17MB)
    - JPG: ~8MB (manual says 7.5MB)
    GX7
    - Raw: ~20MB (manual says 68 Raw+JPG images on 2GB card, or about 29MB for Raw+JPG Large)
    - JPG: ~7MB

    I can understand why the jpegs are different, and why there's a fair amount of variability within each camera. I don't understand why the Raw files for these two 16mp cameras should be so different. Anyone have any thoughts?

    In any event, the observed difference between the two is close enough (23MB vs 27MB) that I'll use 25MB as an average. So my maximum of 3,000 images (based on prior experience) would fit on three 32GB cards. My plan therefore would be five cards total, with nightly copies to a hard drive. I'll take a few older cards as spares just in case something bazaar happens, like I shoot too much.
     
  2. Different levels of compression are also applied to raw files, be it "lossless" compression or in some cases "lossy" compression (see various discussion on the Sony A7 cameras for an example).
     
  3. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    And some raw formats have med-resolution preview jpegs embedded.

    Barry
     
  4. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    The size of raw files will also vary on the subject matter and ISO speed. Are you comparing sufficiently comparable shots?
     
  5. CiaranCReilly

    CiaranCReilly Mu-43 Veteran

    481
    Oct 18, 2012
    Dublin
    Ciaran Reilly
    It looks like the GX7 embeds fairly decent quality JPGs in RAWs - when I shoot in monochrome JPG+RAW mode, when I import RAWs to Aperture they display in monochrome until they are all freshly rendered by Aperture.
     
  6. dwig

    dwig Mu-43 Top Veteran

    622
    Jun 26, 2010
    Key West FL
    also, the bit depth can vary between different RAW files.

    Summary:
    1. RAW files can be compressed/lossy, compressed/lossless, or uncompressed.
    2. RAW files can be 8bpp, 12bpp, ...
    3. RAW files can have embedded JPEG previews of varying resolution and varying compression
    4. RAW files can have varying amounts of embedded metadata

    This last one will have only a small effect on file size. The other 3 can produce significant size differences for files of the same resolution.