According to the Arducam doc, their Motorized Focus Camera has a 54°×41° field of view, (roughly) equivalent to an old-school wide(-ish) angle 35 mm lens on a 35 mm still camera. For my simple purposes, the camera will be focused on objects within maybe 200 mm:
The numeric keys are 6.36 mm = ¼ inch tall, the function keys are 5.3 mm tall, and the rows are 10 to 11 mm apart.
The focusing equation converting distance to lens DAC values depends critically on my crude measurements, so the focus distance accuracy isn’t spot on. Bonus: there’s plenty of room for discussion about where the zero origin should be, but given the tune-for-best-picture nature of focusing, it’s good enough.
I set the
CANCEL legend at 50 mm and it’s in good focus with the lens set to that distance:
Focusing at 55 mm sharpens the
ON key legend, while the
CANCEL legend remains reasonably crisp:
Adding another 5 mm to focus at 60 mm near the front of the second row shows the DoF is maybe 15 mm total:
Focusing at 65 mm, near the middle of the second row, softens the first and fourth rows. Both of the middle two rows seem OK, making the DoF about 20 mm overall:
Jumping to 100 mm, near the top of the first function row:
At 150 mm, about the top of the far row just under the display:
I think 200 mm may be the far limit of useful detail for a 5 MP camera:
At 300 mm the DoF includes the mug at 600 mm, but the calculator keyboard is uselessly fuzzy:
At 500 mm, the mug becomes as crisp as it’ll get and the text on the box at 750 mm is entirely legible:
At 1000 mm, which is basically the edge of the desk all this junk sits atop, the mug and text become slightly fuzzy, so the DoF doesn’t quite reach them:
I limited the focus range to 1500 mm, which doesn’t much change the results:
I could focus-stack a set of still images along the entire range to get one of those unnatural everything-in-focus pictures.