I actually do not understand what is a back button focus. My camera has a Fn1 button which is bind to AEL/AFL which I don’t think I have used it before.
Back button focus can be set up in most cameras to decouple focussing from the shutter button. So you hold a button to focus and then you can shoot as many pictures as you want with the shutter button. Think of it as automated manual focus.
This is the Godox flash module I use. I recalled setting up the sync with my camera. All my shoots with this flash has been done using this configuration.
Oh I was just testing the shutter speed to confirm the correct figure. So this was done without any lens attached. The one below would be with a lens attached.
I believe this might actually be more relevant when I shoot at con where moving + posters may distract or fool the auto-focus due to face detection? I will actually try single AF + no face detection and see how it goes
There is a way to “fix it in hardware” when the subject you want to photograph is not moving much but anything you do not want captured is:
ND-filter, tripod, long exposure (5+ seconds)
I dont know how to do it in Gimp, but usually you have to “paste” something else to cover what you want gone.
It is easier with moving-shot video:
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And paint your subject orange or blue-green, which may draw the ire of other photographers.
Focus illuminator compromised photos can sometimes be salvaged by conversion to BW, but most would prefer not to have any to begin with.
A good thing about large aperture lenses is that you won’t need such supplemental illumination nearly as much.
I’ll look for the settings and give it a try. Seems like quite a bit of experimenting going in this weekend
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An example of a shot going out of focus. I remembered I did focused on the face before making the shot. This was not noticed on camera screen by us
Yeah, that’s just out of focus. Background is clearly sharp and the way her face is diffused is clearly done by the lens. I expect that to get fixed when you switch from AF-C to single point AF-S.
That photo looked to be focused on the background.
Focal point may have changed between when you saw the indicated focus point and the shutter release. The camera may have jumped focus onto one of the faces - or eyes - in the background.
Some cameras store where the focus point is in each picture’s EXIF data and/or in the raw image. You can find out what happened with that, if it is available.
This seems to suggest it’s focus on the face tho. Unless it was the face detection messing things up. I have since turned it off.
F1.7 is focusing on hard mode.
What other focus settings do you have available?
I dont understand what do you mean by focusing on hard mode
The shallower the DoF, the less margin for AF error.
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Hard to see what’s going on, if that really is the focus point used. Try S-AF at 100% zoom on some test target at similar distances, maybe.
Make sure your camera’s firmware is at the last version available, assuming that had no issues itself. These sometimes contained AF performance fixes, however unlikely that being the actual problem here. Make sure to follow all instructions provided if you upgrade.
Manual focusing lenses wider than f/2.0 can be hard, though it should not be for a properly functioning AF chain even on a mid-2010s camera.
But also the more light getting through the lens, the easier it is for the sensor to “see” where to focus.
In the end we are looking at the equivalent of a 40mm f/3.4 here. Any AF can do that when used with the right settings.
As noted upthread, the EM-5 II is CDAF, not PDAF.
Doesn’t really matter. Issue is backfocus exceeds front DoF.
I’m not familiar enough with Olympus AF to say with any confidence but, given how moronic most AF algorithms are, face priority ignoring the focus point to pick a different face is certainly plausible.
S-AF with face priority off should be a good test towards reverse engineering the algorithm. @JWNoctis’s 100% suggestion’s a good check for evaluating whether focus can be correct in simpler conditions.
Of the four mid-2010s ILC bodies I’ve owned, they were all too stupid to manage basic stuff like this entirely reliably and were not uncommonly outperformed by point and shoots and phones’ greater DoF.
While @RazorLR1 at least hasn’t mentioned the EM-5 II crashing or locking up so hard as to require battery removal and lens changes to reset, technically it may not actually be a defect. Usually the default’s to allow (e-)shutter release without focus lock, so if the shutter button’s getting pressed before focus confirmation’s displayed then an out of focus image is expected. Or it could be wrong face confirmation.
Having only briefly used an EM-1 out of Olympus’ offerings I can’t really assess how likely this hypothesis might be. But it’s at least not wildly inconsistent with practical observations I’ve read from others on Olympus CDAF behavior in this era.
And where do you think CDAF happens, mr. smarty-pants? 
I’m aware of the differences but both happen on the same component in a mirrorless camera.
… bruh 
Idk if this helps, but this sudden out of focus problem only occurred when I was using the prime lens. I never have this issue for the kit lens. I did suspect it might be because of the wider aperture (f/1.7 vs f/3.5+) I was operating at. The combo of 1/50 + f/3.5+ was my settings with kit lens.
I didn’t fine tune the settings or test it much till the con day itself.