Manual focus more precise?

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Stein Rune Risa New Member • Posts: 17
Manual focus more precise?

I purchased an RF 35mm f/1.8 for my Canon RP. This is a great little lens.

I tested the sharpness by taking some photos of some white paper with printed text on. The text had some jagged edges so it was easy to see the sharpness. I take the photos very closely - maybe 10-15 cm distance.

What I experience is that I can focus manually more precisely than the autofocus. The difference is subtle, but I can see it if I zoom max on the photos taken.

Is this as expected?

I guess that even with spot autofocus, it is difficult to know if the camera actually focus exactly at the letter that I want? The DOF is very narrow at f/1.8 and 10-15 cm - maybe 0.6 mm.

If I do manual focus, I can magnify and get the focus spot on.

As there are no micro focus adjustments on the camera, there is nothing to do there either.

Any thoughts?

A separate question - a bit difficult to explain, but I'll try:

How does the camera interact with the lens to focus? Does it "for a period" analyze the picture it sees through the lens and then adjusts the lens forward/back to achieve optimal focus based on the focus-analyses? Or has the lens "pre set steps" that the camera utilise (i.e. does not "see" the picture and adjust lens - but tells lens to "go to focus distance xx)?

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