For those tech savvy low vision folks who have been handily using their iPhone cameras to capture images of restaurant menus and then using zoom to enlarge it to double the size for easy viewing, iOS has upgraded their native Magnifier app to reduce the steps needed to produce a great and sharp image for your needs. The app also serves to support travelers who need to read street signs or view pedestrian signals in real time.
To activate the Magnifier app, go into settings, general, accessibility, Magnifier and turn it on. Now it is available whenever you triple click the home button. If you have additional accessibility features attached to your home button, Magnifier becomes one of the choices displayed.
Along the tool bar at the bottom you have options to turn on a light, freeze the image (which does NOT save it to photos), choose from high contrast colors/reverse images. If you did want to save the image permanently, you can screen shot it. For reading in a restaurant in low light, this option is far superior to using the camera live and zoomed when you are subject to using only available light. Having the flexibility to freeze/release the image (touching the image again releases it) with a light makes reading in low light much more convenient and with fewer steps. Note, the freezing process also improves image quality if you have a slight tremor or handshake. When using the magnifier at distance for reading street signs or pedestrian signals, you don't need to save and delete images, and you can monitor and respond to signals changing in real time, rather than taking a photo and then zooming in on it.