DOC Calculator Tool in Magic ViewFinder apps is quite innovative yet extremely simple to use.
Once you press DOF button on the main screen you enter the DOF calculator:
Accordingly you can see the near and far limits of the sharp area (the blue lines) — the Depth-of-Field. The DOF doesn’t depend on the camera or the sensor you are using. That is why you should also adjust the focal length of the lens (the dark blue wheel on the right).
You can also see the Hyperfocal Distance value only if you have purchased Premium Features.
You can change the distance and the aperture simultaneously by tapping the screen:
NOTE: though the lines for the near and far limits of the DOF (the blue lines) seem to be equally away from the focus mark (red line) the actual distances are not equal (the vertical axis for the focusing distance is not linear).
If you turn on the BLUR MAP switch you can see a very important map of the blurriness:
The green area shows the size of the minimal sharp detail at any distance up to the infinity. The wider the green area is, the larger is the amount of the non-sharpness. In other words, anything smaller than that size will be totally blurred (sometimes this size is called the Disc of Confusion). As you can see the blurriness decreases as you approach the focus point, where it turns zero, and then it grows as it approaches the infinity.
To measure the size the Disc of Confusion turn on the CHECK switch (available only in Premium Features):
One example from the picture above: let’s assume that you have a paper with a word written on it. The letters written on that paper are 3mm tall. If your lens is set at the focal length of 58mm (the blue wheel on the right) and is focused at the distance of 3.24m (the red line) then if you place the paper at the distance of 1.27m from the camera (provided the aperture is f/10.9), the word on the paper will be blurred so that it can be hardly discerned. How do we know that? From the screen above the minimal sharp object at the distance of 1.27m is 3.2mm. Anything less will not be sharp.