Reader Question: Is A Larger RAW File Better?
I recently received the following reader question from Michael S.:
Does the size of the raw file make a difference as to the quality of the final image? Looking at nikon d90 with raw file size around 10mb, sony a550 about 14 and the canon t1i around 20. is larger better? I have googled this question for hours and cannot find an answer.
My answer is after the jump, but if any of my readers have additional information to share with Michael please do so by adding a comment to this post. Thanks!
Mike,
The reason you’re not finding the answer to your question is because the size of the RAW file is determined by the sensor resolution. The more data captured by the sensor the greater the size of the RAW file. More resolution isn’t always better particularly in smaller sensor where pixels are smaller and packed closer together. This creates a greater amount of digital noise at higher ISO settings.
Note: Even with in the same camera different ISO settings can result in different amounts of data stored with in a RAW file impacting its overall size.
Clearly higher resolution sensors (those with more megapixel) are going to provide you more data to create larger prints. For prints under 8×12 most any 10+MP camera will suffice. If you’re looking to make really large prints then you may want to consider a higher resolution camera, but image enlargements can be made with lower resolution cameras with the proper software depending on the subject. Images with less detail are more forgiving with enlargements while images with a great amount of detail are not.
As of late there has been debate as to the necessity of higher resolution sensors if digital noise is kept to a minimum in smaller resolution sensors. NIkon’s introduction of sensors capable of capturing nearly noise free images at 4000 ISO revived this debate. Ultimately there are multiple paths to the same destination of high quality prints. While evaluating sensor resolution and noise characteristics are key aspects to any camera purchase decision you should also factor in other features that each camera provides.
So the answer to the question, “Is larger better?”
RAW file size is determined by the size of your sensor and can vary depending on your photos ISO settings. As to what sensor size you opt for depends on what your goals are with your photography and how much noise you’re willing to endure. Most any dSLRs at this stage will result in great images for the web. Different dSLRs will result in differing degrees of print quality and size.
I hope my answer and those of my readers help you in your camera selection.
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Jim, This is true when comparing raw files of the same manufacturer and similar cameras, but different raw formats might use diverse data structures and compression techniques, making the file size vary.
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GearOracle is correct. The file size is loosely correlated with the number of pixels but there are enough other factors at play that make it pretty arbitrary. Different sensor technologies, file formats, and compression algorithms will produce different size files regardless of the image size or quality.
One minor correction for GearOracle's post: even comparing raw files from the same manufacturer is not always a very meaningful exercise. Some scenes will produce data that compresses better than others, even using the same algorithm.
Guy
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There's a caveat here that is rather important. While the amount of data in the unprocessed raw file is a function of the resolution of the sensor, some manufacturers' raw formats actually compress the raw data in the file (using some lossless algorithm, I expect). As far as I can remember, this applies to Nikon's NEF format but I don't know whether Canon do something similar. As a result, the size of the file will vary depending upon the image content as well as the resolution.
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Very well explained, Jim. Cheers!
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Like all things in photography, the answer is “it depends”. The two main factors that impact RAW size are number of megapixels (10,12,24, …) and bit depth (12,14).
Let's start with the easy one. Files with a larger BIT Depth are better. Bit Depth is basically the number of shades of red/green/blue that a sensor can capture. More is always better.
Now, resolution/megapixels. There are 2 things to consider here – sensor size and pixel density. If you have the same sized sensor, at some point, more pixels will create more noise – for example the Nikon D3X (24MP) has significantly more noise at higher ISO than the 12MP D3 (a full comparison is at http://www.jonmccormack.com/blog/?p=41).
So – if you are shooting landscapes where you can keep the ISO down, a bigger RAW sizis better. If you are shooting sports or indoors where you need a high ISO, bigger RAWs may reduce your image quality.
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Thanks to everyone who has commented adding to my answer for Michael. The different compression types for each makes RAW format was something I forgot about. Seeing as these compression algorithms are intended to be lossless it would not seem to me that this would make one larger/smaller RAW file better or worse. As always keep the answers coming. Everyone's participation is what makes our photo community so great.
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[...] really breaks it down in his simple easy-to-understand language. Check out the discussion: Is A Larger RAW File Better? (JMG Galleries) [...]
Within a single camera, RAW file size can vary by as much as 2 MB at a single ISO setting. I think it has to do with the amount of information stored in the file.
For instance, if I take a photo of aspen trees, with lots of leaves and detail (probably related to resolution), the file will be larger than if I take an image of a silhouette against a cloudless sky. There's simply more information stored in the first file than the second one.
I'm not sure the two differ in image quality (i.e. sharpness, etc), though.
Am I correct?
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i am the original poster of this question and i still don't see an answer to hang my hat on. am new to digital slr and have settled on the pentax k7 which can store raw files in either pentax “format” or dng. the ” spec” sheet states that raw files are 25mb. it doesn't state if this is at iso 100 or whatever or if the shooting scene is complicated or not (snowy field vs. picture of fans at a football game). i found a discussion on dpreview that was somewhat related.
http://forums.dpreview.com/forums/read.asp?foru....
are we comparing aples to aples?
michael
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Within a single camera, RAW file size can vary by as much as 2 MB at a single ISO setting. I think it has to do with the amount of information stored in the file.
For instance, if I take a photo of aspen trees, with lots of leaves and detail (probably related to resolution), the file will be larger than if I take an image of a silhouette against a cloudless sky. There's simply more information stored in the first file than the second one.
I'm not sure the two differ in image quality (i.e. sharpness, etc), though.
Am I correct?
[Reply]
i am the original poster of this question and i still don't see an answer to hang my hat on. am new to digital slr and have settled on the pentax k7 which can store raw files in either pentax “format” or dng. the ” spec” sheet states that raw files are 25mb. it doesn't state if this is at iso 100 or whatever or if the shooting scene is complicated or not (snowy field vs. picture of fans at a football game). i found a discussion on dpreview that was somewhat related.
http://forums.dpreview.com/forums/read.asp?foru....
are we comparing aples to aples?
michael
[Reply]