As a professional photographer I am always concerned with getting my images to look the best they possibly can. That means paying the extra money for fast glass, shooting RAW files instead of JPG (even though it takes longer to edit and takes more file storage space), using remote flash units and more.
So when app makers started unveiling the ability to create RAW files on iPhones I was excited. There are limitations to do it right now though. You need to have a new enough device that your camera is a 12 MP (which my iPhone 6s has), and you need to be using iOS 10. Wait a minute. What was that last part? iOS 10? It is not out yet. So for the last several weeks I have been using the iOS 10 beta system on my phone.
Why shoot RAW? A simplified explanation is that all cameras have to do some computer processing to your image to turn it into a JPG file. This includes applying sharpening, locking in white balance, setting the contrast level and more. A JPG image is also a compressed image. The computer (there is a computer in the camera/phone) does the compression and in order to make the file small for storage and for uploading/downloading. It does this by simplifying the pixels in your pictures. It looks at areas of the photo and it says that this group of pixels here are all very similar in color, so we are going to package them together and say they are all the same color. This mean that it is lowering the quality of the image. By shooting RAW the pictures are not compressed and sharpened. The pixels are all as the sensor recorded them, and you get to edit them the way you like. Just remember that when you edit a RAW file if you save it as a JPG file you are doing the compression yourself.
By shooting RAW you get to control how much sharpening is applied to your image and you also get to avoid the artifacts in the images that come from the compression that goes into your image being made into a small file.
In short, shooting RAW will give you the pixels untouched and in the best quality. Like I said, I want the best quality I can get. So shooting RAW is a no-brainer, right?
It is not quite that simple.
You could make the argument that RAW does not matter for most iPhone users since the images will be going to social media like Instagram and Facebook which add their own compression to the files and negate the effort of shooting RAW. Not only that, the vast majority of these images are viewed on small mobile device screens and the images will not be carefully examined. But not shooting RAW means that your image is being compromised two or three times -- the JPG compression of the phone is lowering your quality right away. Then when/if you make edits it saves the fie and applies the JPG compression again - compressing and damaging the pixels that have already been compressed. Then when you post it the site runs their own compression scheme on the image, lowering the quality again. If you shoot RAW to begin with you are getting the image at the best possible quality and getting rid of the first image compression step, so the image is higher quality when it goes to the social media site.
The ultimate answer is that you need to decide what works best for you. If you have an iPhone 6 or older the point is moot - your phone will not let you do RAW files. If you have a newer iPhone and can do RAW you still have to consider the larger file size (how much memory does your iPhone have to store the bigger picture files?) and your own workflow. Does the app you use support RAW? Google's app, Snapseed and ProCam 4 by Tap Tap Tap both have RAW support - but what about other apps like Aviary or Mextures or Photogene4?
For me, if image quality is truly critical I am going to bring out my Nikon DSLR kit and shoot with the bigger sensor and higher quality lenses to get the best possible image. That does not mean however that I am going to not shoot the best quality image I can get with my phone. I have the iPhone 6s with 128GB so I am not squeezed for space on my phone. For me, shooting RAW makes sense.
As a side note, until the official release of iOS 10 comes on Sept 13th I have to run the beta version.
Running the beta has proven that not everything works yet (that's why it
is beta). The app that got me really interested in iPhoneography is
Hipstamatic. The app has hundreds of different lens and film
combinations (filters, really) to get an amazing range of looks to your
images. In the beta version of iOS 10 the Hipstamatic app (and its
sister app Oggl) do not work properly. The camera works, but being able
to go into other images and apply the filter crashes the program. In
Oggl I cannot even add a photo to the editing section.
I have been in contact with the people at Hipstamatic and they are hard at work making sure their app will be fully functional when the official non-beta release rolls out (scheduled) on Sept. 13 In the meantime I will just shoot with Hipstamatic like it was the classic version where you can't edit after the fact.