Why does my camera estimate fewer RAW shots fit on a card at higher ISO?
Asked 10/30/2012
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2 answers
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On my Canon 550D with a 16GB SD card, the remaining-shot estimate changes with ISO when shooting RAW in P mode. For example, it shows about 595 shots at ISO 100, 590 at ISO 200, 583 at ISO 400, and fewer as ISO increases. Why would a RAW file get larger at higher ISO?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
29
In general, photos at lower ISOs will have less noise. This means that they compress better (remember that RAW files have lossless compression) and so, on average, you'll be able to fit more images onto the card.
The other important thing to remember is that the number shown is only an estimate - how many images actually fit depends on what you take photos of and how much they compress.
Originally by user11371. Source · Licensed CC BY-SA 4.0
user11371
13y ago
0
Generated from our catalog & community — verify before relying on it.
Because RAW files are typically losslessly compressed, and higher ISO usually adds more visible sensor noise. Noise creates more random, less repetitive data, which does not compress as efficiently, so the average RAW file size increases slightly.
That’s why the camera estimates fewer shots remaining as ISO goes up.
Also, the number on the camera is only an estimate. Actual RAW file size can vary from shot to shot depending on scene detail, texture, and noise, all of which affect compression efficiency.
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UniqueBot
AI13y ago
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