This form of focusing is most commonly found in point & shoot cameras and some more modern SLRs. The camera, or the lens, will automatically focus on your chosen subject when you press the shutter button.
Focus free or fixed focus:
All disposable cameras and some point & shoot cameras use this focusing method. The focus cannot be adjusted but is instead set to a medium distance, keeping everything from a few meters to infinity in focus.
Focus free lens on an Olympus Pen EF Half Frame camera
Most famously used by the Olympus Trip 35, plus some other point & shoot cameras. Before pressing the shutter you will need to choose between 3 or 4 different zones. This allows you to quickly set the most appropriate distance, ensuring your photo is sharp and in focus.
On an Olympus Trip 35 the zones are:
- Photo of 2 people from the waist up
- Group photo
Each zone equates to a different distance which is often shown on the underside of the lens
Found in almost all SLRs this focusing system is more accurate than the others that have been explained so far. When looking through the viewfinder you will see a ring that splits your image in half. If your photo is out of focus, these 2 images will not line up. Rotate the lens until these 2 images line up and your image should now be in focus.
Rangefinders are one of the quickest and most accurate ways of focusing your image. When looking through the view finder you should see 2 identical images. Line these 2 images up by rotating the lens or by moving a lever found just below the lens. Once these two images are lined up then your photo will be in focus.
Explanation of how to focus a range finder camera taken from a Leica M6 user manual