Raw and JPG file sizes - E-M1 and GX7

bassman

Mu-43 All-Pro
Joined
Apr 22, 2013
Messages
1,043
Location
New Jersey
Real Name
The Bassman
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.
 
Joined
Oct 9, 2010
Messages
7,397
Location
Brisbane, Australia
Real Name
Nic
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).
 

CiaranCReilly

Mu-43 Veteran
Joined
Oct 18, 2012
Messages
487
Location
Dublin
Real Name
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.
 

dwig

Mu-43 Top Veteran
Joined
Jun 26, 2010
Messages
717
Location
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.
 
Top Bottom