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Uncompressed RAW File Sizes for Stills (Sony a7iii)

hooty

By hooty,
in Sony Alpha Full Frame Cameras

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hooty Newbie

hooty

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I am using the Sony a7iii and it appears that uncompressed RAW for stills is 14-bit. However, the specs show that the uncompressed raw for 16:9 resolution is 14-bit but doesn't mention bit depth in the 3:2 which I will use. Should I assume that the 3:2 ratio is also 14-bit? If so, then my main question is this...

If the RAW file is 14-bit depth at 24 megapixels, then is the correct calculation:

  • 24,240,576 pixels X 14 bits = 339,368,064 bits

  • 339,368,064 bits / 8 = 42,421,008 bytes

The file sizes I am getting in the .arw are about 49,668,000 bytes so I was curious what is the overhead in this RAW file? Why is it 7,000,000 bytes more than this calculation?

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Cameratose Rising Star

Cameratose

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It is 14-bit @ 3:2. As for the rest, no idea. Not sure why it matters? What is it you're trying to determine?

 

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hooty Newbie

hooty

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Good to know it's 14-bit. The page I found only shows 14-bit for the 16:9 ratio and not 3:2 which was the only reason it was a question. https://www.sony.com/electronics/support/e-mount-body-ilce-7-series/ilce-7m3/specifications

As for the other stuff, the reason I ask is because I'd like a decent understanding of what I'm working with. I know it doesn't matter to most people but I have a personal curiosity about it. I am trying to understand more about what a RAW file actually is, how it got there (because of the amount of pixels on the sensor and each pixel's bit depth) and then from that RAW file, understanding that a piece of software would have to triple this size when it interpolates the RAW bytes. 

I've been reading all week and I think I have my answer but just wanted it clarified here.

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FunWithCameras Community Regular

FunWithCameras

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First off, uncompressed 14 bit data is not stored packed together - each 14 bit sample is stored in 2 bytes (16 bits).

Also, bear in mind that a RAW data file has more samples than there are pixels in the finished image - you need samples beyond the edges to be able to interpolate full colour information for the pixels on the edges. 

And yes, it's 14 bit data for the full 3:2 image.

The ARW file holds more than the RAW data, too - it holds metadata about the image, and it holds a JPEG that can be used to show a thumbnail.

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    • XKAES
      JPEG options?

      By XKAES · Posted

      I'd suggest you start by running a simple test.  Take pictures of a typical scene/subject and each of the JPEG settings your camera offers.  Then compare them in the output that you normally produce.  You may or may not see a difference.  I normally shoot at the highest JPEG level and save that file -- but make a smaller file (lower resolution) for normal/typical use. There's plenty of editing that you can do with JPEGs on your computer -- depending on your software -- and there are features in your camera that can help out, as well.  That depends on your camera.  Put them together, and it might meet your needs.  For example, your camera probably has several bracketing features that will take the same shot with different settings with one press of the button.  Then you can select the best JPEG to work with on your computer.  I frequently use this feature to control contrast.
    • Cameratose
      JPEG options?

      By Cameratose · Posted

      If you set up some basic presets in your processing software and use batch processing, you don't need jpeg at all. I shoot RAW only, use (free) Faststone Image Viewer which will view any type of image file to cull my shots, and batch process in Darktable. I can start with 2000-3000 shots and in a matter of a few hours have them culled, processed, and posted. A handful of shots, say a couple hundred from a photo walk, are done in minutes.  This saves card space, computer space, and upload time.  The results are very good for posting online. When someone wants to buy one or I decide to print it, I can then return to the RAW file and process it individually for optimum results.  I never delete a RAW file. Sometimes I'll return to an old shot I processed several years ago and reprocess it. I have been very surprised how much better they look as my processing skills improved.  
    • Pieter
      JPEG options?

      By Pieter · Posted

      If you're only publishing small-sized photo's or viewing on a phone / computer screen, 12-ish MP should be more than enough for your needs. Since with JPEG, the ability to 'fix' stuff on the computer is very limited anyway, you're not giving up much except the ability to crop/recompose after taking the shot. If you tend to crop often or might print large, shoot fine quality instead as JPEGs don't take up a lot of space anyway. I tend to shoot RAW+JPEG. After a trip/shoot, I download my photos to my computer and quickly scan through my JPEGs to select my keepers. The JPEGs are fine for 90% of my needs but at times there are one or two 'WOW'-shots that I might one day print large. I'll edit the RAW of these photos to my hearts content, generate a JPEG, then delete all RAWs to clear up space.

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