How to make a PDF from photos or pictures
Make a PDF from photos with File > New > From pictures in PDF by Zaweba: a page per picture, JPEGs kept byte for byte, multi-page TIFFs one page per frame.

Photos become a PDF through File > New > From pictures in PDF by Zaweba. Choose the pictures and you get one page per picture, each at the picture's own resolution, in a single PDF. Multi-page TIFF and GIF files give a page for every frame, so a fax or a scanned stack saved as one TIFF opens as a proper multi-page document.
It's what you need for sending phone photos of receipts to an accounts department, putting scanned pages of a form into one file, or turning a set of drawings into something you can email in one go.
Your pictures, kept as they are
Quality is the thing people worry about with converters, and the way PDF by Zaweba handles pictures is careful about it.
JPEG photos go into the PDF byte for byte. They're not decoded and squeezed again, so there's no second round of compression and nothing gets softer or blockier. Other formats are stored losslessly, which means every pixel arrives exactly as it was.
Each page is made at the picture's own resolution, so a sharp photo stays sharp and a small picture isn't blown up into a blurry one.
Formats it reads
PDF by Zaweba reads JPEG, PNG, TIFF, GIF, BMP, JPEG XR and ICO pictures. That covers phone photos, screenshots, scanner output and most images you'll find on a PC. JPEG 2000 isn't read, so convert those to another format first if you have any.
Making the PDF
Before you start, put the pictures in a folder and name them in the order you want them, such as 01, 02, 03. It saves reordering later.
Choose File > New > From pictures and select the pictures. The new PDF opens in a tab, not yet saved. Scroll through it, and if any page needs to move, drag its thumbnail. A photo taken sideways can be turned with Ctrl+R. Then save it with a name that says what it is.
If the PDF will be emailed and the photos are large, File > Reduce file size can make it smaller, with presets from Balanced to Smallest file.
Tidying the pages
Phone photos of paper often have a bit of table or floor round the edge. Pages > Crop pages lets you drag a rectangle to keep just the document, and Remove white margins trims plain borders automatically.
If you're adding pictures to a document you already have rather than starting a new one, insert them instead. Pages can be inserted from a copied picture on the clipboard, and File > New can also make a PDF straight from whatever picture is on the clipboard, which is quick for a single screenshot.
When the pictures are pages of text
A photo of a letter is still a photo. The words in it are part of the picture, so they can't be selected or searched like the text in a PDF made from a document. That's fine for keeping records and sending copies. If you need to copy the words out, bear in mind they aren't text yet.
PDF by Zaweba is free software for Windows that works offline with no account, so personal photos and scanned papers become PDFs on your own PC without being uploaded anywhere.