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Olympus OM-D E-M1 Mark II The second Micro Four Thirds camera that offers phase detect focusing so you can use Four Thirds DSLR lenses normally as well a Micro Four Thirds lenses.

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Old 24th July 2017
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Re: AF Fine Adjustment on E-M1 Mk II

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Originally Posted by DanC.Licks View Post
Part of the problem is in the nature of CDAF and PDAF systems, and trying to combine them. One thinks closer is best and the other thinks further away is best, so when the camera tries to think and decide which AF system it is going to use for what kind of image (as I understand it it does not use both at the same time) it can get confused. According to the expert on the German Oly forum, there is never any need to fine adjustment when the camera uses CDAF, but it MIGHT need it with PDAF. Confusing...
That all said, a +10 adjustment is HUGE! My trusty old 50-200 has I think +1 on the long end, otherwise nothing. My Canon 400/Metabones is bang on every time on my thet chart. Unfortunately though, we don't buy cameras to take pictures of test charts, and real world situations are harder to manage.
It would not surprise me if there are improvements on the way via via firmware updates. Hope so...
It would be great if we could connect our brains to the camera via Bluetooth or something so it would know what WE want rather than decide for its self.
Hi,
I spent some time testing the AF accurracy of the Canon 400/Metabones and the Zuiko 300/2.8 on the E-M1 and E-M1 Mark 2, photographing a focus chart at 45 degrees angle in controlled conditions (good light, tripod, paying attention when aiming etc...). With/without TC, 10 frames for each combination, 100 frames in total.

For illustrative purpose below is the worst sample from the population (E-M1 M2 + Zuiko 300/2.8, 5mm back focus)


What took most time was reviewing the results. To reduce the impact of human factor I reviewed two times with a break in between, and if there was a delta of 2mm or more between reviews of same frame I did a third, definitive review. This way I feel confident that the review was fair.

The results?

Both cameras back-focus when using the 300/2.8, about 2 mm.
E-M1/E-M1 M2
Average 1,7/2,3
Std dev 0,9/0,9

Both cameras seem accurate with the Canon 400/5.6 and Metabones. 0,5 may be within the resolution limit. Not all frames are spot on though.
E-M1/E-M1 M2
Average 0,0/0,5
Std dev 1,5/1,2

How much adjustment should be applied to compensate for 1 mm backfocus?
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Old 24th July 2017
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Re: AF Fine Adjustment on E-M1 Mk II

Tord, I had to add +4 to the tele end of the 50-200 EC14 on the E-M1 (haven't done so on the Mk II because the 50-200 is now faulty), so it is necessary to do the 4/3's lenses (or other AF lenses with adapter).
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Re: AF Fine Adjustment on E-M1 Mk II

Tord,
I am not sure that sort of chart is best for Oly cameras, even with cross type AF points. They don't react well to horizontal lines. So if you use that chart you can rotate the camera 45°, or use something like this that gives the camera plenty to focus on on one clear plane of focus.
36087005366_2ce172530b_z.jpg
36086923316_130062dbe9_z.jpg
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Re: AF Fine Adjustment on E-M1 Mk II

Furthermore as the camera has 121 cross type points, which ACTUAL POINTS are dual? I mainly use single centre sometimes 5 point and occasionally 9 point.
Doing a lot of nature photography in the field as to speak I have found that when the subject i.e. A bird is out of focus it's usually the operator error, when reviewing images later on the computer one can see with the aid of the focus point (small green rectangle) wether you have nailed the target.

When using the 300pro and MC14 you are waving around an equivalent 840 mm lens hand held this scenario is common especially for birds in flight or that small passerine in a thicket. I have not interfered with focus adjustment thus far.
Kind regards Mike
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Re: AF Fine Adjustment on E-M1 Mk II

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Originally Posted by DanC.Licks View Post
Tord,
I am not sure that sort of chart is best for Oly cameras, even with cross type AF points. They don't react well to horizontal lines. So if you use that chart you can rotate the camera 45°, or use something like this that gives the camera plenty to focus on on one clear plane of focus.
Yes, and the instruction to angle the camera at 45 degrees is printed on the chart. Perhaps it was taken at 45 degrees but processed to appear upright when posted here?
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Re: AF Fine Adjustment on E-M1 Mk II

Hi Dan,

When shooting with the Mark 1 I rotated the camera 90 degrees, or it simply would not acquire focus. When rotated it aqcuired focus without hesitation. The Mark 2 acquired focus regardless of orientation. So I think it works in that aspect.

Thinking about it, the line in the chart I used is a tad thick, 2 mm when viewed at 45 degrees angle so that may explain some of the deviations, but not the 2mm average back focus. Your chart eliminates such uncertainties but introduces risk of mechanical misalignment.
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Re: AF Fine Adjustment on E-M1 Mk II

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Originally Posted by Growltiger View Post
Yes, and the instruction to angle the camera at 45 degrees is printed on the chart. Perhaps it was taken at 45 degrees but processed to appear upright when posted here?
I rotated the camera 90 degrees when shooting so all RAW frames have portrait orientation. The picture I shared is a horizontal crop resized to 1024x768 as the forum photo processing software will reduce quality if you exceed the max lenght/width. (At least, it did so in the past).
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Re: AF Fine Adjustment on E-M1 Mk II

Right. I still wonder though how the camera likes focusing on something at an angle rather than parallel to the focal pane.
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Re: AF Fine Adjustment on E-M1 Mk II

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Originally Posted by DanC.Licks View Post
Right. I still wonder though how the camera likes focusing on something at an angle rather than parallel to the focal pane.
Some focus tools eliminate that problem by having a flat target precisely aligned with the focal point of the sloping sheet. This seems the safest option.
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Re: AF Fine Adjustment on E-M1 Mk II

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Originally Posted by Mdb2 View Post
Furthermore as the camera has 121 cross type points, which ACTUAL POINTS are dual? I mainly use single centre sometimes 5 point and occasionally 9 point.
Doing a lot of nature photography in the field as to speak I have found that when the subject i.e. A bird is out of focus it's usually the operator error when reviewing images later on the computer one can see with the aid of the focus point (small green rectangle) wether you have nailed the target.

When using the 300pro and MC14 you are waving around an equivalent 840 mm lens hand held this scenario is common especially for birds in flight or that small passerine in a thicke. I have not interfered with focus adjustment.
Kind regards Mike
Mike,

These are with 4/3 lenses, not m4/3.

I started using the E-M1 Mark 1 with the 300/2.8 a few years back and was never really satisfied with the results that were showing inaccurate focus (back) and also some spread. This was never an issue with the 50-200 and 12-60 SWD. The solution was easy - use the trusted E5 when using the 300/2.8, with that combo there is no backfocusing issue. Now that I also have the E-M1 Mark 2 I would like to take advantage of it (or the Mark 1 for that matter) with the the 300/2.8 and that's why I ran the test as preparations for calibration.
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Re: AF Fine Adjustment on E-M1 Mk II

I calibrated by photographing a high resolution focus chart perpendicular to the camera and found that adjustment of 1, 2 or 3 depending on camera and lens provided sharpest results. These values happen to be same as the mm values I measured when photographing the scale at 45 degrees angle - coincidence I guess. Then I ran the first test again and now the average out of focus is less than 1mm.
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Re: AF Fine Adjustment on E-M1 Mk II

I spent lots of time watching various YouTube videos, differing techniques on how to calibrate AF and picked pointers from these.

EM-1 mk2 - jpg LSF with increased contrast and sharpness, to assist when reviewing the images. Using a Spyder Lenscal focus tool, camera on tripod, IS-off and
single point/ s-af. All my lenses are M4/3 and I manually de-focused between each shot, to allow af to refocus. There's recommended min/max (lens to focus target) distance's for each focal length tested and lens aperture should be wide open.
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Old 25th July 2017
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Re: AF Fine Adjustment on E-M1 Mk II

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All my lenses are M4/3 and I manually de-focused between each shot, to allow af to refocus.
How many did you change, and by how much?

Recommended distance is about 30 times focal length - so a 300mm would be 9 metres, but perhaps we should double that for m4/3?
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Re: AF Fine Adjustment on E-M1 Mk II

I calibrated my
12-40mm 2.8 / 45mm 1.8 / 40-150mm 2.8 and 40-150mm + mc-14
The 40-150mm + mc-14 registers in the data set, as a 56-210 F4.0

With the 12-40mm I settled at -2 Tele/ -1 Wide
40-150mm -2 Tele/ no adjustment at Wide
45mm +4
56-210mm -7 ( I probably hadn't worked out how to adjust and save both ends of zoom when I did this calibration, will check again soon )

Was working at approx distance, 25x of each focal length tested.


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Re: AF Fine Adjustment on E-M1 Mk II

Thanks Mark. That's interesting. I've been happy with my lenses but perhaps I should test the 40-150mm with TC.
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