Ooh, baby, we like it RAW. Yes. I went there.
The past few days, I've had a lot of traffic to my Why you should shoot in RAW article/infographic. That's great, but a few people on the internet here and there feel that I have been giving a skewed view of things; that it is a little bit more complicated than that.
Truth is, whenever I buy a new camera body, I set it to 'raw', and leave it there. I like the extra flexibility it gives me, and it fits very well with my shooting style.
Taking photos in RAW has one potential downside: It takes up a lot of extra space (around 10x more, compared to JPEG). The file size issue has three different impacts, and I'd like to talk about both with you:
JPEG takes up less space
It is undeniably true that JPEG files are a fraction of the size of RAW files. On a practical level, that means that you need more memory cards if you take a lot of photos, and you need more harddrive space. However, I would argue that harddrive space is cheap these days, and a couple of high-speed, high-quality memory cards are within the financial range of all photographers who can afford a camera that takes RAW file photos in the first place.
I can't really come up with a reality where the 'taking up storage space' is a valid argument: If you're willing to significantly reduce the flexibility of your post-production workflow just to save a few megabytes of storage space, then I would suggest it's time to take another look at why you are taking photos, and why you bothered with a SLR in the first place.
JPEG is faster to save to memory card
Now, the bottleneck in the camera isn't actually the processing: JPEG files take a lot of processing by the camera, but cameras have specialised processors to do this for you - and high-end SLR cameras actually have multiple processors to make this all happen at lightning speed.
What slows down your work, is that you can only write to memory card so fast. A camera has a buffer built in, which gives you a bit of leniency, but of you are taking photos in rapid succession, this buffer can get full. When it does, the camera has to write the photos to the memory card before you can take another photo. When that happens, you are met with a "writing" or "busy" message, and your camera stops taking photos for a few seconds.
JPEG files, because they take up so little space, can be written to the memory card quite quickly. RAW files, on the other hand, are much, much bigger. The result is that they fill up your photography buffer much faster, and your camera stops taking photos much faster, too.
If you are taking photos in an environment where speed is of the essence (sports, events, etc), and where you are unlikely to have to do a lot of post-production, JPEG files are your only alternative. It is worth keeping in mind, however, that you have to get the white balance, exposure, and all your in-camera settings spot on: If you don't, there's only so much tweaking you can do in post production before you start losing data.
JPEG is faster to process
The final argument is that JPEG files are faster to process on older computers, because RAW files are huge in size, and contain a lot of extra data. In addition, even simple changes to a RAW file require the computer to read the RAW file, re-render it, and show it to you. JPEG files don't need re-rendering because they are already rendered.
I think this is another daft argument, to be honest; Sure, it's annoying to have to sit there, waiting for your files to render so you can look at them properly, but ultimately, most photographers are only interested in one thing: Getting the best possible photos. Why anyone would choose to use a file format that reduces your flexibility in post
Can photos taken in JPEG be as good as photos taken in RAW?
There's a quirk with this question: The human eye can't actually distinguish that many colours, and 8-bit JPEG files are more than plenty for showing all the colors and details that humans are able to perceive in a photograph. So, as an output format, JPEG is perfectly adequate.
If you are taking photos in a studio, with perfect lighting, perfect exposure settings, and a manually set white balance, with a completely flawless subject, then there is no reason for why you should need to do any post-processing whatsoever. If the photos that come out of your camera are the way you want them to look, then taking them in RAW is a waste of time and resources.
It is also true that JPEG isn't as inflexible a file format as some think. You have a fair bit of leniency in making white balance, minor exposure, and other edits to your photo. The problem is that if you are planning to do extensive editing (say, you're photographing a model and you want to retouch the image to make her look better), then the fact that the file started off as a JPG means that there will be some data loss (up to 20%) already: Nearly imperceptible compression artefacts will have snuck into the file, and the next time you save it as a JPG, you are introducing further artefacts. Every time you re-save a JPG file, you are degrading the image quality.
Of course, it is possible to do 'lossless' editing on JPG files in software like Lightroom or Aperture, but you still get twice the amount of compression artefacts: One set introduced by the camera, and another set introduced by you, when you export the final image.
A final consideration is whether you trust the technology; the noise reduction done by your camera might be very good today, but in five years, they will have introduced new technology. If you have your photos in RAW, you can re-render them with current technology (in Lightroom, run "Update to current process"), and you'll find that the noise is lower, the colors are smoother, and the quality of your images is higher - all because you still had the original RAW data captured by your camera. The differences can be rather astonishing.
By shooting in JPEG, you are in essence taking a bet that you believe that what the camera can do for your photos, is as good a quality as you will ever need, and that no future development in photo software algorithms will be worth your while.
So to answer the original question: If you take perfect photos every time, JPEG can be as good as RAW - but never better. If you take less than perfect photos, and you put the quality of your photos ahead of anything else, RAW is the only choice.
TL;DR (Too long; didn't read):
- Get near-perfect exposures every time
- Get near-perfect white balance every time
- Have your camera set to the right contrast settings for your preferences
- Have your camera set to the right sharpening settings for your target media
- Are not going to do any extensive post-production
- Need to be able to take a lot of photos in quick succession
- Don't believe that future developments can make a positive impact on your photos
... You can start considering to shoot in JPEG.