the photo you took, not a copy of it
A JPG can go into a PDF unchanged — most converters change it anyway
JPEG is already the format PDF stores photos in. Decoding a photo and re-encoding it on the way in is pure loss: slightly softer detail, sometimes a bigger file, and no way to get the original back out.
This page embeds your JPG bytes as they are. It also respects the orientation flag your camera wrote, so the portrait shots that some tools lay on their side come out the right way up here.
three steps
How to convert JPG to PDF
Add your photos
Drop in as many JPG files as you like.
Set the order and page
Rearrange with ↑ and ↓, then pick size, orientation and margins.
Download
One PDF with a page per photo.