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EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF
  
 
James Farrell
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p.1 #1 · p.1 #1 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


As a new user of the Oly EM-1 Mark 2, I just returned from my first outing with this new camera and my new Oly 40-150 f/2.8 Pro and 12-100 f/4 IS Pro lenses. I spent 5 days at the Bosque NWR and the Bernardo NWR in New Mexico. I enjoyed using the Oly system (I had my Nikon D500 and lenses with me as well but purposely did not use them much.)

One unusual thing that I have noticed after reviewing images on a large monitor at home is there seems to be some front focusing happening when shooting in C-AF focus mode. To be more specific, I shot ALL my images with the EM-1.2 using C-AF, even shots where there was NO motion instead of switching to S-AF.

So, today I shot a number of test images - C-AF vs S-AF - with my EM-1.2 and my Oly 40-150/2.8 using a Lens Align test target and the corresponding slanted ruler (single focus point, centered, timer release shutter) shot in RAW ORFs. What I noticed was that using S-AF the test shots were in perfect focus. However, the C-AF test shots, otherwise using the same setup, were all front focused.

Now, I admit to not knowing all of the nuances of the EM-1.2 having had it only for just under 2 weeks. That said, I'm just wondering why I am getting different focus results using S-AF and C-AF.



Feb 12, 2017 at 09:54 PM
rxgolf
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p.1 #2 · p.1 #2 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


Hi James,
I am anxious for the micro 4/3's experienced users to hopefully respond. On my 100-400 Pany I dialed in +2 and that is now close in Single. In C AF I am not so sure but I figured that maybe it was just not as accurate as S AF as that has seemed to be the case with other bodies I have used. OR it could be I don't know what I am doing!
I look forward to seeing your post going forward!
Sincerely,
Greg



Feb 12, 2017 at 10:37 PM
James Farrell
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p.1 #3 · p.1 #3 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


rxgolf wrote:
Hi James,
I am anxious for the micro 4/3's experienced users to hopefully respond. On my 100-400 Pany I dialed in +2 and that is now close in Single. In C AF I am not so sure but I figured that maybe it was just not as accurate as S AF as that has seemed to be the case with other bodies I have used. OR it could be I don't know what I am doing!
I look forward to seeing your post going forward!
Sincerely,
Greg


Well, I hope to get feedback too, Greg. Thanks for chiming in. I suspect, but I am only making a guess, that there is a combination of focusing systems in play here. Since I've seen the EM-1.2's AF system described as a "Hybrid" system (I think meaning a combination of Contrast Detection and Phase Detection) that perhaps S-AF is contrast and C-AF is phase (or perhaps a combination of the two). At any rate, the S-AF is very accurate, the C-AF not so much. I am standing by to be corrected and set straight.



Feb 12, 2017 at 11:18 PM
k-h.a.w
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p.1 #4 · p.1 #4 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


AFAIK S-AF is Contrast Detection focus. C-AF is Phase Detection focus only, no fine tuning with Contrast Detection at the end.
One can micro adjust C-AF in the E-M1.2. It also helps to half press the shutter button until a green indicator shows focus has been achieved.
My E-M1.2 is set up to achieve focus before it can fire also for C-AF. I don't use f-numbers larger than 8. YMMV.

Maybe your lens should be adjusted or replaced.

Good luck James, K-H.




Feb 14, 2017 at 05:37 PM
James Farrell
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p.1 #5 · p.1 #5 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


k-h.a.w wrote:
AFAIK S-AF is Contrast Detection focus. C-AF is Phase Detection focus only, no fine tuning with Contrast Detection at the end.
One can micro adjust C-AF in the E-M1.2. It also helps to half press the shutter button until a green indicator shows focus has been achieved.
My E-M1.2 is set up to achieve focus before it can fire also for C-AF. I don't use f-numbers larger than 8. YMMV.

Maybe your lens should be adjusted or replaced.

Good luck James, K-H.



Thanks for your response and post. Coincidentally, I learned just this morning that my Oly 40-150 f/2.8 Pro lens firmware had a lens firmware update available per Oly's lens support page. So, I completed that just a few moments ago. I am aware that one can micro-adjust AF in the E-M1.2 - but now that the firmware has been updated (and according to the info on Oly's support page and firmware update notes for the 40-150 f/2.8 Pro, auto focus should be improved as the E-M1.2 is specifically mentioned) I suspect that this issue should be resolved. We shall see.



Feb 14, 2017 at 06:23 PM
k-h.a.w
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p.1 #6 · p.1 #6 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


Thanks James. Yup, I updated all my lenses. Forgot about that. Sorry.
Please let us know if that solved the problem. TIA.

K-H.



Feb 14, 2017 at 06:26 PM
 

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James Farrell
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p.1 #7 · p.1 #7 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


k-h.a.w wrote:
Thanks James. Yup, I updated all my lenses. Forgot about that. Sorry.
Please let us know if that solved the problem. TIA.

K-H.


Thought I'd offer some follow up and maybe closure on the original post in this thread (don't like to leave issues unresolved or un-reported). After updating the firmware of my 40-150/2.8 Pro, it now seems that the focus performance between S-AF and C-AF has evened out on my E-M1.2. I now note that the 40-150/2.8 Pro was back focusing somewhat. So, I did a slight adjustment to the AF fine tuning and now everything seems OK. Likely that I'll have to retest if or when Oly issues a firmware update to the E-M1.2 down the road. But that's easy to do.



Feb 15, 2017 at 06:12 PM
k-h.a.w
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p.1 #8 · p.1 #8 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


Thanks James.

Cheers, Karl-Heinz.



Feb 15, 2017 at 06:22 PM
bobbytan
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p.1 #9 · p.1 #9 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


Just stumbled on this article about AF optimization:

http://www.ayton.id.au/wiki/doku.php?id=photo:olympusem5_af

The link is broken, so you will have to do a cut-and-paste.



Feb 21, 2017 at 07:10 PM
James Farrell
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p.1 #10 · p.1 #10 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


bobbytan wrote:
Just stumbled on this article about AF optimization:

http://www.ayton.id.au/wiki/doku.php?id=photo:olympusem5_af

The link is broken, so you will have to do a cut-and-paste.


I tried to read this article but had to give up as it made my head hurt. Too much info. Like reading an article about a dozen ways to make soup.



Feb 21, 2017 at 09:11 PM
bobbytan
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p.1 #11 · p.1 #11 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


I know. I didn't bother to read it myself.

James Farrell wrote:
I tried to read this article but had to give up as it made my head hurt. Too much info. Like reading an article about a dozen ways to make soup.





Feb 21, 2017 at 11:06 PM
ajamils
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p.1 #12 · p.1 #12 · EM-1.2 New User Inquiry RE Focus Performance: C-AF vs S-AF


Here is the fixed link

bobbytan wrote:
Just stumbled on this article about AF optimization:

http://www.ayton.id.au/wiki/doku.php?id=photo:olympusem5_af

The link is broken, so you will have to do a cut-and-paste.





Feb 22, 2017 at 12:13 AM







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