I tried a mirrorless. Have you?

JeremieB wrote:

Mark Ransom wrote:

JeremieB wrote:

As an easier method, they could just use the "good focus" information, that we see in viewfinder. That's the AF system saying "not focused" or "good focus" or "not very good focus" (blink). If they have access to a continuous value they can use that (and repeat multiple times to average). If they have only 3 states, they can still use that to deduce a value (and again, repeat several times ...). The advantage if automatized is that this method could be blazing fast, even if configured to take many samples for each value (just move out of focus / refocus / save focus indicator).

The "good focus" indicator is driven by the same AF system you're trying to calibrate. Until the calibration is complete it's worthless.

You would start from a perfectly focused image (using live view for example), because of course you need a reference, then calibrate the AF with method above. I didn't invent it, was shared on YouTube and here (the full method is to detect the range of fine tuning values where AF indicator shows good AF then take the middle value).

This is a method I have tried, without fantastic success.

1. focus the camera in LV mode.
2. switch to OVF.
3. focus and see if the lens moves.
4. adjust correction and redo 1-3.

The adjustments where the lens do not move are acceptable adjustments.

This is a tedious method and whether the lens moves or not is not reliable.