What are RAW files?
RAW is the general name for any image file that a DSLR creates that has not been processed. For example, point and shoot cameras will typically apply a blanket picture style to your photos before saving them in the JPG format. That picture style can increase saturation so that the colors are more vibrant. This helps to reduce any post processing and works just fine for most people with a point and shoot. In DSLRs you can choose from a myriad of options to get the result you want. RAW is just one of those options and it delivers what the camera sensor sees, unaltered.
RAW is not an industry standard file format like JPG for example. The JPG format has a set of specifications created by a governing body. This means that JPG files can be shared, edited and read in any number of applications that conform to the JPG standard. RAW files and the specifications that define them are all uniquely the property of the individual camera manufacturers. So a RAW file created by a Canon camera is not the same as a RAW file created by a Nikon camera. Canon currently creates a .CR2 file extension and Nikon creates a .NEF file extension, although both are considered RAW. Both are loosely based on the TIFF format (Tagged Image File Format) which is widely accepted as an extremely strong and comprehensive image format. But both Nikon and Canon’s RAW files are tweaked specifically for their cameras. In fact the RAW files created by these manufacturers have been known to vary from camera to camera.
Adobe has their own RAW format called DNG (Digital Negative). Their argument is, because RAW files created by Canon and Nikon for example are proprietary you may be held over a barrel at some point in the future. DNG is an open source format and so available for anyone to use. A lot of the smaller camera manufacturers have adopted DNG. Sony uses the ARW format. Personally I don’t see any of the larger manufacturers using their RAW format in a negative way at anytime in the near future.
Why do we need RAW?
Unlike the majority of image file formats that are most commonly used PNG, JPG, etc., RAW files allow us to work with natively with the highest quality image. RAW files are non-destructive meaning that you can’t actually save in RAW. There are no applications that allow you to save changes to a RAW file. You can open them and you can edit them. In Photoshop when you close a RAW file after making adjustments it will create an XMP file, also known as a sidecar file, which is associated with the RAW file. Any adjustments you make to the RAW file are saved in this XMP file and when you reopen a RAW file the XMP file open with it and allows you to continue to make adjustments where you left off. However at no time is the RAW file changed. Therefore it is non-destructive and you can always return to the original without fear that you may have lost something. Both files are associated but the RAW file is in no way dependent on the XMP file. You can delete the XMP file and all that will be lost is the metadata. When you reopen the RAW file it will have the original settings.
In fact in the Camera RAW software that Photoshop uses to make adjustments to RAW files the sliders are always set to the middle and if you move a slider in error you can double click it and it will automatically be reset to the original, middle setting. You can see from this screenshot that the title bar specifically calls this software “Camera RAW 8.4 Canon EOS 5D Mark III”
We can tell from that information that this is version 8.4 of the RAW processing software and because it knows which camera was used to take the photo it knows what to expect from the file.
RAW files are typically lossless images meaning that they store ALL of the information that the camera sensor picks up. Point and Shoot cameras will typically want to modify the file when storing it and in doing so they create a ‘Lossy’ file which ultimately means bits lost and in one way or another a degradation in the image. Also RAW files come with the benefit of a higher dynamic range and the ability, in the right software, to make adjustments that just feel more native to the image.
That said RAW files typically are going to want at least some minimal processing outside the camera.
More about the XMP “Sidecar” file.
XMP (Extensible Metadata Platform) is a trademark of Adobe but is a widely adopted open source industry standard, but again it is a sidecar file and so needs a parent file association.
What are the consequences of using RAW?
With all of the information that is packed into RAW files, they are big. Most DSLR cameras make RAW an option when saving images and not the default. You can set most DSLR’s to create any combination of RAW and JPG files (RAW or JPG or RAW and JPG). The reason DSLR’s give you both is because you need special software to make adjustments to RAW files, and also for most people JPG files are just fine. If you need something quick to use and yet you want to retain the power of a RAW image then you may just want to have your camera create both. In that way you can deliver the JPG immediately and yet still have the RAW to work with as needed.
However, all of this comes at a cost. RAW files are larger than JPG. For example this image in RAW format is 25.94 MB and without any processing it’s JPG counterpart is 11.26 MB.
Creating both can eat up your storage and take more time to process in-camera. Which means that they are going to slow things down. A lot of DSLRs now provide specifications on how many images you can shoot in burst mode before you should expect the buffer to fill. Here’s a link for Canon users.
If there is no need for speed (subliminal Top Gun reference) and because storage costs are still shrinking, your trade-off differential may be negligible.
FYI: Be aware that out of the box Windows will not display a thumbnail for RAW files in Windows Explorer. Microsoft have not made photography part of their core business so it’s not a format Windows understands. If you create only RAW and want to sort through your photos you will need to have another application like Adobe Bridge in order to be able to view RAW thumbnails. There is a Viewer plug-in for Windows 7 called the Microsoft Camera Codec Pack. It can be downloaded here:
If you really need to view thumbnails of RAW files in Windows Explorer then this might be a way to do it. Personally, as a photographer I rarely consider Microsoft products because there are so many other companies doing great work and generating good software that are more dedicated to this specific industry.
Should you use RAW Files?
Yes and No. I mostly shoot in RAW to give myself the most flexibility after the shoot. On occasion though, I have worked events where they need the photos immediately and in a relatively small size. In that instance I’ve shot exclusively in JPG. What is the end result you are looking for and what might you want to do with those images down the road? This will help you determine whether to shoot in RAW or otherwise.
Once you have a RAW file open you can of course save it to any one of the existing formats in order to be able to use it as needed, on the web, in print, etc.
Lots of options to consider. DSLR camera manufacturers have been very good at providing options. Instead of forcing an opinion on us they continue to deliver great flexibility.