iPads and iPhones do so many things. Scanning documents is another task iOS has taken on, and an app called PDF Scanner (US$2.99, universal) does the job quite well.
To get started, just point your iPhone's or iPad's camera at a document or book, and the app focuses and creates a clear scan of the text. What's nice is that PDF Scanner can recognize a book open to two pages, get both sides and create two separate PDF files ready for export. Without that feature, you would do a lot of cropping to get everything just right.
You can tell the app to scan in color or black-and-white. In my tests, I was just doing text so I opted for monochrome. The results were very sharp. Once the scan is done, you can open the file in any app that supports PDF format. I had no problem using iBooks or the Kindle app. You can also send the file to various cloud-based servers like Google Drive. You also get an option to mail the file, send it to Dropbox, move or rename the file and print it. On my laser printer, the scans were tack sharp.
I would have liked to see the app do character recognition so I could turn the document into editable text, but the developers say the resources needed to do a reliable job just aren't present on iDevices. There is consideration of sending the files to remote servers for character recognition, but that's a feature we may or may not see in the future. I tend to agree with this conclusion. The OCR software I've tried in iOS has a very high error rate. What the app does very well, using some complex algorithms, is adjust for distortions from a curved page in an open book. I verified that this worked quite well.
PDF Scanner is a solid app, and is on sale for a short time for US$2.99, 50 percent off the regular price. If you need to quickly turn documents into PDFs, PDF Scanner is worth serious consideration.
The app is universal and should be used with the rear camera of your iDevice, which has the best resolution. The app requires iOS 6.0 or greater.