Timeline for Why aren't faces sharp in my f/1.8 portraits even though I'm carefully using center-point autofocus?
Current License: CC BY-SA 4.0
10 events
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| Sep 30, 2019 at 7:14 | comment | added | Michael C | @Russell_McMahon It's for speed. The camera can go ahead and begin to close the shutter curtain (or clear the sensor if you're using electronic shutter) in preparation for the exposure while the lens is still being moved to the desired focus position without taking a "confirmation" AF reading. The calibration is for the amount of difference between the distance the lens was instructed to move versus the distance the lens actually moved. | |
| Sep 30, 2019 at 0:22 | comment | added | Russell McMahon | @MichaelC Yes, for full mirrorlesses. I thought about my comment before posting. | The pellicle mirror SLT's I mentioned do of course still have the issue because they divert (typically) ~= 30% / half a stop of light to the phase-focus sensors. | Mirrorless cameras with contrast focusing should never have the problem, and mirriorless cameras with phase detection sensors in the main sensor should not either - BUT eg both my Sony NEX-5N & Alpha 6300 mirrorless have an "AF microadjust" feature . [Why needs investigating ...]. | |
| Sep 29, 2019 at 14:39 | comment | added | Michael C | Most mirrorless cameras that use the main imaging sensor to AF should have no front/back focusing issues unless something is causing the lens to move between AF and exposure. In such a case, perhaps one should check that one is not inadvertently moving the lens' focus ring? | |
| Sep 29, 2019 at 9:54 | comment | added | Russell McMahon | @MichaelC Yes, the method 'has it's issues' - but it's still useful for intended use, with "due care". A single shot may mislead. A little intelligent experimenting will allow good results. The target can be, if desired, a series of flat faced pillars or palings, or ... . Having permanent live view with an electronic viewfinder helps. (eg only: Sony SLT or newer) | |
| Sep 29, 2019 at 6:37 | comment | added | Michael C | Shooting at an angled object without a properly aligned flat target parallel to the camera's image plane is not a reliable method for checking back/front focus. There are several possible ways that one can get false results because the camera decided to focus on something different than what is showing directly below the AF "point" in the viewfinder. | |
| Sep 25, 2019 at 8:00 | history | edited | Russell McMahon | CC BY-SA 4.0 |
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| Sep 25, 2019 at 7:53 | history | edited | Russell McMahon | CC BY-SA 4.0 |
added 177 characters in body
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| Sep 24, 2019 at 7:09 | comment | added | Russell McMahon | @MichaelC I suspected so - but the visual alignment check is still useful. Then there is manual playing :-). | |
| Sep 24, 2019 at 3:01 | comment | added | Michael C | No AFMA with the Rebel T6/1300D. | |
| Sep 24, 2019 at 1:24 | history | answered | Russell McMahon | CC BY-SA 4.0 |