Given my interest in panoramic photography, I’ve recently been researching cameras and seeing what aspect ratios are commonly used. Nobody asked for this, but here’s a comparison showing the same photo cropped to various aspect ratios ordered by size, along with what types of cameras use each. This isn’t intended to be a complete list, but just a general guide:
3:1
Used by various 35mm panoramic cameras, though the physical photo prints I measured from a disposable 35mm panoramic camera were actually 2.875:1
17:6
Used by 617 medium format film cameras
65:24
Used by Hasselblad XPan / Fuji TX film cameras and available as an option on a few digital cameras like the Fuji GFX series and various Panasonic full frame cameras
2.35:1
A common cinematography aspect ratio, included mostly for reference since I’m not aware of any still photography cameras that fully support this [the Sony A7C II and possibly other Sony cameras can preview photos at 2.35:1, but you still have to crop them in post]
21:9
Available as an option on Sigma Quattro digital cameras and possibly others
12:6
Used by the Holga 120 Pan camera, though photos I’ve seen online are actually closer to 21:9
16:9
An option available on many digital cameras, and is the common widescreen television aspect ratio
3:2
The most common aspect ratio used for still photography, initially as the standard 35mm film format and borrowed by most digital camera manufacturers… it’s also the same aspect ratio used by various 6×9 medium format film cameras
4:3
Used by micro four thirds cameras as well as 645 medium format film cameras. and is the standard “fullscreen” television aspect ratio
5:4
Used by various large format cameras
7:6
Used by various 6×7 medium format cameras
1:1
Used by various 120 film medium format cameras, Polaroid cameras, Instagram, and uh… Plastipic.