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View Full Version : AF Fine Adjustment on E-M1 Mk II


Ross the fiddler
23rd June 2017, 04:03 AM
EDIT: (Mon 26/6/2017) Please look here for a very good explanation of how the Mk II differs with AF to that of the E-M1 with a better understanding on how to use it. http://pen-and-tell.blogspot.com.au/2016/12/e-m1ii-der-neue-af.html

I decided to try the 40-150 Pro with the MC14 on the new body when I heard some birds outside. Of course they weren't around when I had the camera, so I took some photos of static objects to try them out & I was disappointed with the results. I know this subject has come up before, but I feel it may need a fresh look. So I tried the lens combination on the E-M1 with fine results. After that I tried the Mk II with Magnified View select (through Fn2, MultiFunction), both with magnification on & off with much better results. My assumption with that was it was now just using CD-AF as the E-M1 was while normal AF (Mk II) was using PD-AF (S-AF). So my next move was to try AF Fine Adjustment at +10 & I got better results. From that quick & rough trial I would suggest it maybe is a good idea to now perform AF Fine Adj with all lenses since it uses PD-AF (+ CD-AF), particularly with lens combinations using a teleconverter. I will make further checks & adjustments to see if there are any differences, but if I suspect a subject is out of focus I can revert to Magnified View selection at +14 (but not with a magnified view though).

My feeling is, they gave us PD-AF with all lenses to perform like a DSLR & therefore it does perform like a DSLR; that is, needing AF Fine Adjustment as well, particularly with lens combinations. In other words, "You can't have your cake & eat it too". That is, AF Fine Adj. is needed on DSLRs & I think so does this camera (as it is provided for DSLR lenses as well as MFT lenses). While the Mk II claims Dual FAST AF system (https://www.olympus.com.au/Products/Interchangeable-Lens-Cameras/Olympus-OM-D/E-M1-Mark-II/Features/High-speed-Performance), so did the Mk I. (https://www.olympus.com.au/Products/Interchangeable-Lens-Cameras/Olympus-OM-D/OM-D-E-M1/Features/Dual-FAST-AF-high-speed-performance) I think a better understanding of when those Dual AF operations occur & when only one does (on each model) would result in a better AF outcome.

The following is quoted from the Mk II (Australian) web page here (https://www.olympus.com.au/Products/Interchangeable-Lens-Cameras/Olympus-OM-D/E-M1-Mark-II/Features/High-speed-Performance).
High-speed AF system

A completely new AF system makes it possible to capture fast-moving subjects. With a Dual FAST AF system that uses the 121-point AF area for both On-chip Phase Detection AF and Contrast AF, the E-M1 Mark II delivers dramatic advancements in AF precision, tracking performance, and operability.

121-point All-cross-type On-chip Phase Detection AF

This E-M1 Mark II is equipped with an 11 x 11 121-point All-cross-type sensor. With an AF area that covers 75% vertically and 80% horizontally, subjects can be tracked across a wide range. All 121 points are cross-type focus points, making subject detection very accurate.

New AF algorithm

The new 121-point All-cross-type On-chip Phase Detection sensor and new TruePic VIII image processor significantly improve focus detection performance. The new moving subject tracking algorithm makes it possible to continue tracking various subject changes.


I welcome comments please.

blu-by-u
23rd June 2017, 04:27 AM
Don't understand.:( I am totally lost. Are you saying that we can select between Contrast or Phase on say the 40-150 pro? And in Phase, I can actually do fine adjustments?

If so, Please show the steps.

Thanks Uncle Ross.

Ross the fiddler
23rd June 2017, 05:33 AM
Don't understand.:( I am totally lost. Are you saying that we can select between Contrast or Phase on say the 40-150 pro? And in Phase, I can actually do fine adjustments?

If so, Please show the steps.

Thanks Uncle Ross.

I think normal S-AF shooting is done predominantly with PD-AF while the Magnified View function, that can be anywhere in the focus area on the screen & can be selected by touch I think is only CD-AF.

So my feeling is; PD-AF usually requires the lens to be calibrated, or adjusted with AF Fine Adj., in camera & this camera has that provision, for all lenses & lens combinations, so we should use it. EDIT: I may have to eat my words with making AF Fine Adjustment with MFT lenses because there is no adjustment amount shown when viewing the thumbnail with info in camera as seen with 4/3's lenses.

Ross the fiddler
23rd June 2017, 06:43 AM
I may have to eat my words with making AF Fine Adjustment with MFT lenses because there is no adjustment amount shown when viewing the thumbnail with info in camera as seen with 4/3's lenses. I will investigate further myself, but if anybody has any official information from Olympus, then I would love to see it.

bassman
23rd June 2017, 11:13 AM
Look forward to hear how you get on with this one, Ross. I have calibrated my lenses, where I felt they've needed doing, including 40-150mm 2.8 +MC-14. Purchased a Spyder Lenscal, used tripod etc and remembering to turn off the image stab'. Easy to get carried away with all this stuff but in my case, definitely worth doing ! All my current lenses are MFT(no 4/3's) and seem to remember I had fun working out how the camera function actually worked. For a zoom lens, you can adjust for the wide and tele end, on that same lens. Once confident how it worked, I was having great fun testing all my lenses and I found you can't spoil anything.... into menu, turn lens data off and you're back where you started.


Mark

OM USer
23rd June 2017, 11:32 AM
Its crazy that you need to make a manual adjustment for the lenses in this day and age. There is a sophisticated processor in the camera and all it has to do (provided it is pointed at the obligatory brick wall, graph paper, or high contrast design) is chunter through the focus range in CDAF looking for when each contast point is in focus and update the PDAF fine adjustment setting accordingly.

Ross the fiddler
23rd June 2017, 11:48 AM
Look forward to hear how you get on with this one, Ross. I have calibrated my lenses, where I felt they've needed doing, including 40-150mm 2.8 +MC-14. Purchased a Spyder Lenscal, used tripod etc and remembering to turn off the image stab'. Easy to get carried away with all this stuff but in my case, definitely worth doing ! All my current lenses are MFT(no 4/3's) and seem to remember I had fun working out how the camera function actually worked. For a zoom lens, you can adjust for the wide and tele end, on that same lens. Once confident how it worked, I was having great fun testing all my lenses and I found you can't spoil anything.... into menu, turn lens data off and you're back where you started.


Mark

So you did do the AF Fine Adj in the Mk II then for those lenses? Great! I only took a quick stab at a +10 for the tele end of the 40-150 Pro & MC14. I'm familiar with using it on the E-M1 (Mk I) with the 50-200 SWD lens & EC14 etc. The Sigma macro lens & EC14 also need it too. I had some doubts about it when the adjustment figure doesn't show when reviewing the images though. I'll do meore checking tomorrow in day light again. Thanks for your feadback. *yes

Ross the fiddler
23rd June 2017, 11:51 AM
Its crazy that you need to make a manual adjustment for the lenses in this day and age. There is a sophisticated processor in the camera and all it has to do (provided it is pointed at the obligatory brick wall, graph paper, or high contrast design) is chunter through the focus range in CDAF looking for when each contast point is in focus and update the PDAF fine adjustment setting accordingly.

You must be thinking of the Nikon system then (or was it Canon?). ;)

DerekW
23rd June 2017, 04:24 PM
I do not understand why a fine adjustment has to be made on a mirrorless camera as the focus sensors are on the same plane as the image sensor (actually part of the image sensor), I can understand why on a dSLR as the focussing device is away from the film plane.

Miketoll
23rd June 2017, 06:01 PM
I do not understand why a fine adjustment has to be made on a mirrorless camera as the focus sensors are on the same plane as the image sensor (actually part of the image sensor), I can understand why on a dSLR as the focussing device is away from the film plane.

Me too Derek.

DanC.Licks
23rd June 2017, 06:48 PM
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.

Ross the fiddler
23rd June 2017, 11:42 PM
I do not understand why a fine adjustment has to be made on a mirrorless camera as the focus sensors are on the same plane as the image sensor (actually part of the image sensor), I can understand why on a dSLR as the focussing device is away from the film plane.

If the camera is using PD-AF it instructs the lens to focus at a particular setting according to the detected phase angle (or whatever it is detecting), & that may not necessarily be exactly in focus at the intended critical point because the lens may not be as accurately calibrated for PD-AF, so a fine adjustment stored in the camera can correct that. The difference here is understanding how the PD-AF is combined with CD-AF & when. I think that 'touch' AF (using magnification method) only uses CD-AF & may get around occasions where (PD-)AF can have anomalies.

DanC.Licks
24th June 2017, 04:53 AM
I have also heard that the AF works slightly differently depending on the mode selected. I only use S-AF (C-AF is useless with the Metabones/Canon rig, not to mention C-AF+Tr) so I can't say, but there was some discussion about just that on the German forum.
It is SO easy to become dependent on AF and once we have it, there is no going back, and we want it to work ALL the time.... surprise... :D

MJ224
24th June 2017, 08:39 AM
All double dutch to me...........

Either the focus works or not. Certainly did not pay 1700+ for the focus system not to work.

Well over my head..........................*chr

Ross the fiddler
24th June 2017, 11:49 AM
All double dutch to me...........

Either the focus works or not. Certainly did not pay 1700+ for the focus system not to work.

Well over my head..........................*chr

When I was trying to focus on an object using the 40-150 Pro lens with the MC14 TC that took more effort than it did on E-M1 then I wanted to find out why & what the differences were & how I can make it at least as reliable in those circumstances. I also didn't pay $2500 to be disappointed either. I'm not sure if anything I've done has really made any difference or not, but I will just be cautious when taking photos where I'm trying to focus on a small area in isolation to the surrounds & if necessary try the Magnification selection (at X 14 size AF box) if needed, in the hope that it may only use CD-AF (for S-AF), giving that further flexibility in the use of the camera.
On going back over the frames I believe IS was part of the issue too. Also, just for the information, I was using Anti-Shock Sequential Low drive mode.

Ross the fiddler
24th June 2017, 11:59 AM
Ross, this is all way beyond me too but then I still haven't got past "GO" on my new O-MD MK1 :) Stop "fiddling" with the new MK2 camera and take some more great photos like you usually do. You know you want to :D:D:D

Best regards,
John

Sorry, but I really need to get out as I don't have much else to add except one little pup that is keeping us busy (along with the three other dogs). :rolleyes:

http://e-group.uk.net/gallery/data/500/K6230361-s.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/93979)

Not even the birds are around much. *shrug

Bassman51
25th June 2017, 12:52 PM
Me too Derek.


My interpretation of the reason is as follows:

PDAF works by calculating where focus SHOULD be, based on the out-of-phase appearance of the image to the focusing sensor, and instructing the lens to move to that focus setting. The camera never actual checks to see if the image IS in focus. Errors can occur because of mechanical tolerances in the lens itself, the lens mount, etc. In DLSRs, errors can also occur because of mechanical tolerances in the separate focusing sensor which is not on the image sensor, hence the greater need for focus adjustments.

CDAF, of the other hand, works by looking at the actual image and determining if it IS in focus. So by definition, there can never be any adjustment needed.

Clearly, Olympus wouldn't have provided the adjustment capability if it weren't useful.

DanC.Licks
25th June 2017, 01:19 PM
Yes. I think you are right.
Olympus had to jump through a few hoops to get on-sensor PDAF to work at all. They have done well, all things considered.

Ross the fiddler
25th June 2017, 01:32 PM
In further testing today, I'm not sure if any adjustment will help the MFT lenses like the the 40-150 Pro lens with the MC14 combination. I would like to know for sure, one way or the other.

DanC.Licks
25th June 2017, 01:38 PM
Don't blame you. It is not as if it were a cheap setup. It SHOULD work.... :confused:

Ross the fiddler
25th June 2017, 02:00 PM
Don't blame you. It is not as if it were a cheap setup. It SHOULD work.... :confused:

It's working OK really, but I just need to know how to best use it correctly.

I was testing it on these red gum leaves & thought it should focus on them rather than the background leaves being PD-AF, but then again, the front red leaves may have been moving. *shrug

The full image using MF (40-150 Pro + MC14).

http://e-group.uk.net/gallery/data/500/K6250693-s.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/94038)

A crop of the above with MF.

http://e-group.uk.net/gallery/data/500/K6250693-scr.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/94039)

A crop of an example using S-AF (low sequential drive mode with IS priority, not fps priority)

http://e-group.uk.net/gallery/data/500/K6250690-scr.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/94037)

It's all OK as I'll just get used to using appropriate settings to get what I want. The camera is a beauty!

DanC.Licks
25th June 2017, 03:27 PM
Ross,
To me the green leaves with yellow spots and yellow edges on them have more contrast than the red leaves and are perhaps more attractive to the AF system. Also, the AF is colorblind though red is sometimes problematic.
I have found in general, that it is somewhat more difficult to be really selective with the Mk II than with the Mk I in situations like that. I feel that the Mk II wants to latch onto the background more than the Mk I, but it could by my imagination, not having held a Mk I for 6 months, and working solely with PDAF with my Canon 400. Here are some test shots I did with the 50-200, which behaves about the same as the Canon/Metabones. The same test using my mFT 75-300 II was revealing in that it was much easier to focus exactly on what I wanted. PDAF and/or CDAF?? Who knows.... ?
Do we know whether the 40-150 Pro + MC-14 uses ONLY PDAF, or does it also use CDAF?
The Oly expert on the German forum wrote a longish comparison of the Mark I and II focus systems, actually somewhat difficult to compare because they are so different. He mentions that the crosses are actually longer than what shows up in the green box, and that they have to be in order for PDAF work. With CDAF the camera examines contrast edges exactly within the box. So his conclusion was that if you want to use FT or adapted lenses and single point, the focus accuracy will be better with the Mark I, otherwise it is Mark II all the way. He also states that you have better chances with 5 or 9 points finding the focus than with single point. My feeling is that although it is easier to be more selective with the 75-300 II, the focus accuracy is better with both the Canon 400 and the 50-200. I have tested them quite a bit with a dedicated focus testing chart, and I get much better results with the two clunkers than with the tiny mFT zoom.
But there again, test charts are one thing, and in the real world, my Mark II seems to find twigs and branches more attractive than fuzzy little baby birds, so I sometimes get nice sharp backgrounds and really fuzzy birds.
Still... I love the camera and I am slowly improving my technique. When it gets it right it is stunning. This series is all with the Mk II, often in difficult light and often difficult situations for the AF. But they are all S-AF, sometimes with a quick manual pre-focus, but not often.
https://www.flickr.com/photos/42162009@N04/albums/72157679178320144
More on the AF comparison next....

DanC.Licks
25th June 2017, 04:19 PM
Here are a few important points covered by Reinhard Wagner in his article. It is in German here:
http://pen-and-tell.blogspot.co.at/2016/12/e-m1ii-der-neue-af.html
His books on all the various Olympus cameras are well known here.
So let me roughly translate/summarize the main points that are relevant to our discussion...

"It is a fact that S-AF on the Mk II works completely differently with FT and mFT lenses.

The cross type sensors on the MkII work quite differently than cross type sensors on a DSLR where "nearest is best" meaning that the closer contrast edge becomes the point of focus. The MkII works completely differently in that it looks for edge quality (contrast) and doesn't care if it is further forward or further back. A black and white contrast edge will be preferred over any other structure, regardless of its position.

If a mFT lens is on the camera, the camera becomes more interested in what is going on AROUND the cross. This means that with a mFT lens attached the camera will likely focus on something other than with a FT lens attached. If there are two contrast edges of equal quality within the field it will become a question of luck which one the camera chooses, further forward or further back.

A further problem with mFT lenses using CDAF arises in that if there is any movement of the camera or the subject, the AF will tell the camera "focus achieved, no need for further adjustment" and you can end up with a blurred shot.

Olympus has put a lot of thought into their AF system, but they don't give us much information on exactly how it works. Where before using 9 or all focus points was something only for birds against a blue sky, it has now become the more sensible option as a single point can behave erratically, but with more points active it is easier for the camera to understand what is nearer and focus on that. With FT lenses it is fast and accurate.

With mFT lenses it can become a problem to have all fields active, as it evaluates both contrast edges and distance, and it will prefer something in the center of the frame rather than something more to the edge, even though it is closer. So here it is better to use 9 or 5 fields, or touch-focus."

Confusing?.... yup! ;) And he hasn't even gotten into C-AF... that can wait. But I find it very interesting and important to understand how an AF system works in order to get the most out of it. Reinhard is an interesting guy, and he knows his stuff, but even his close contacts with Olympus doesn't mean that they will lay all their cards on the table.

DanC.Licks
25th June 2017, 04:23 PM
One more point,
"With FT lenses, only PDAF is used. With mFT lenses, in S-AF both PDAF and CDAF are used, and with C-AF, again only PDAF."



and....

"One thing is clear, red is still evil! Plain red areas and red cloth are still a big problem for AF."

Phill D
25th June 2017, 08:50 PM
Blimey this is all pretty confusing, my head hurts from reading this thread in one go to catch up. Just let us mortals know when you guys have sorted it all out and tell us what to do. In the meantime I'll take it that I can now blame the camera for any out of focus shots I get ;)

Ross the fiddler
26th June 2017, 12:06 AM
One more point,
"With FT lenses, only PDAF is used. With mFT lenses, in S-AF both PDAF and CDAF are used, and with C-AF, again only PDAF."



and....

"One thing is clear, red is still evil! Plain red areas and red cloth are still a big problem for AF."

Thanks very much for all of that Dan & I love all those bird images on flickr. *yes

Both red & what I also saw in Google's English translation (plus you quoting it),
"Another important finding is that the cross-sensors of the E-M1II react differently than cross-sensors in DSLR cameras. For these, the closer contrast edge is the edge to be focused on. "Nearest is best". The cross sensors of the E-M1II work completely differently. They determine the quality of the contrast edge and the camera then focuses on the best contrast edge. Whether it is front or rear, is not relevant for the camera."
now makes it much clearer to me. The other static object where it had issues was an old red connection box on my neighbour's redundant TV antenna pole. It seemed to work well with the same lens combination on the E-M1 & not so great on the Mk II & is why I started wondering why & what were the real differences. This information you have passed on confirms what I am seeing & makes better sense on the Mk II behaviour & hence, makes it clearer on how to use it. Another less distinct subject are banksia flower spikes that are barely larger than the focus box. Most of my interest for the small focus area is to grab that elusive bird shot as they visit our place, but being winter they aren't as active around here now (I haven't been putting out bribing seed either).

These are what I was testing AF on & where they weren't behaving as well as I had expected.

http://e-group.uk.net/gallery/data/500/K6260700-s.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/94050) http://e-group.uk.net/gallery/data/500/K6260738-s.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/94051)

And a crop of the above.
http://e-group.uk.net/gallery/data/500/K6260738-xscr.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/94052)

Thanks again for all your help here as it answers most of my questions very well. Some things may just need MF assistance & since the Pro lens have a manual focus ring on it so easy to use it I will likely use that more on occasions (so long as it isn't a bird that won't cooperate).

*chr

Ross the fiddler
26th June 2017, 12:12 AM
Blimey this is all pretty confusing, my head hurts from reading this thread in one go to catch up. Just let us mortals know when you guys have sorted it all out and tell us what to do. In the meantime I'll take it that I can now blame the camera for any out of focus shots I get ;)

My take on it: leave the AF Fine Adjustment alone except for Four Thirds DSLR lenses & take note of how the PD-AF with CD-AF on the Mk II actually achieves focus & note that red objects might not be as easy to focus on as one might assume (red does appear dark in B&W) as described here, http://pen-and-tell.blogspot.com.au/2016/12/e-m1ii-der-neue-af.html (using Google translate).

I've also added this into the opening of the thread, so others don't have to 'hurt their head' in trying to find it. ;)

brasche
26th June 2017, 03:45 AM
One of the first tests I did with my new E-M1 mk2 in December was to play with the AF Fine Adjustment.

The bottom line is that with my 40-150mm Pro, changing the adjustment had no effect when using S-AF, however it had the desired effect using C-AF.

From this I concluded that (with M.Zuiko lenses and no adapter) S-AF uses CDAF while C-AF uses PDAF.

I did not repeat the test for my other lenses. I was using the regular sized center focus point. The lens was wide open and at maximum zoom.

BTW, the focus point of my 40-150mm Pro did not need adjustment.

Ross the fiddler
26th June 2017, 04:32 AM
Finally a bird to test on. :rolleyes:

I could not get focus on the bird's head in this so focussed on the feet & branch & recomposed.

http://e-group.uk.net/gallery/data/500/K6260780-s.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/94053)

This is a crop of the above to show there is detail to be had if focussed OK.

http://e-group.uk.net/gallery/data/500/K6260780-scr-s.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/94054)

*chr

DanC.Licks
26th June 2017, 06:34 AM
Phil,
Believe me, I feel your pain! ;)
Here are some simple hints on how to go about it...
1. Point
2. Shoot
3. Enjoy
*chr
and finally..
4. Don't pay attention to us trolls :D

Seriously though, this is such a great camera and it can do so much and the AF is worlds better than what it was not all that long ago. Some of us like to fuss and fiddle, but that is part of the game, discovering a new system and trying to figure out how it works and what the fine points are. Keeps "ze leetle gray cells" from drying up all together.
My favorite camera/lens for two years was the E-M1 I with a Canon 400/5.6 mounted on it, all MF only and wide open. It could DELIVER!
4178
Then came the revelation in the form of a firmware update for the Metabones Smart Adapter that allowed AF! Keeper rate skyrocketed! Now with the Mark II I have gotten really spoiled. It delivers so consistently and produces such good results, and I still feel that I am after 6 months and over 10,000 shots just beginning to really get a grip on it, and I don't even have the luxury of the wonderful Oly Pro lenses! Still so happy with the Canon 400 I am not even tempted by something like the Panaleica 100-400 that would no doubt be more practical, but would be a step down on the long end. To me it is a question of understanding and accepting the limitations of the system being used to get the most out of it.

PS. I use S-AF/MF all the time with my Canon and FT lenses. Especially with long lenses and ESPECIALLY when the light is not great, the EVF and focus peaking etc are a real boon! If there is enough time, it is best not to rely on ANY AF system entirely (and that includes C&N).
I think of AF as a time saver. If there is time, AF or AF+MF is fine, but if there isn't, AF is a lifesaver.

Tordan58
24th July 2017, 07:57 AM
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)
http://www.e-group.uk.net/gallery/data/2043/P7180056.jpg

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?

Ross the fiddler
24th July 2017, 08:14 AM
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).

DanC.Licks
24th July 2017, 09:27 AM
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.
4248
4247

Mdb2
24th July 2017, 09:28 AM
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

Growltiger
24th July 2017, 09:38 AM
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?

Tordan58
24th July 2017, 09:41 AM
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.

Tordan58
24th July 2017, 09:46 AM
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).

DanC.Licks
24th July 2017, 09:50 AM
Right. I still wonder though how the camera likes focusing on something at an angle rather than parallel to the focal pane.

Growltiger
24th July 2017, 09:58 AM
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.

Tordan58
24th July 2017, 09:58 AM
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.

Tordan58
24th July 2017, 02:52 PM
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.

bassman
24th July 2017, 07:11 PM
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.

Bengeo
25th July 2017, 08:59 AM
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?

bassman
25th July 2017, 06:01 PM
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.


Mark

Bengeo
25th July 2017, 06:34 PM
Thanks Mark. That's interesting. I've been happy with my lenses but perhaps I should test the 40-150mm with TC.

c12402
30th July 2017, 10:17 PM
After some BIF pictures using 75-300mk2 with a difficulty getting pin sharp results, I decided to calibrate the lens in the em1.2.

Two conclussions:
- the calibration System is quite good and easy to use.
- the lens had not any issue that can be corrected with calibration, when testing similar BIF cases using 40-150 Pro, my results were much better so the cheaper lens did not focus the same way a pro model did with this camera.

Ross the fiddler
30th July 2017, 11:27 PM
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.


Mark

I still have my doubts with M4/3's lenses as it doesn't save them with actual lens ID (lens model & ser no.) as it does with 4/3's lenses where it identifies the lens & TC combination etc.
With the 40-150 Pro lens & the MC14, the MC14 is a 'dumb' device & only identified in the lens with that extra connection pin (two on the lens, for possible other TCs), which then is in the lens data reported to the camera from the lens. The MC14 has a serial number but I haven't found any serial number for it in the EXIF data though (like I can for the lens). BTW, KUSO Exif Viewer V3.0 identifies the 40-150 Pro lens as Olympus Zuiko Digital 35mm F3.5 Macro Unknown Release (16) (unlike Oly Viewer 3 which IDs it correctly + MC14) but does give the lens serial number & firmware version.

bassman
31st July 2017, 06:29 PM
Think I understand Ross, must admit I'd not looked for it in EXIF data. The lens + adjustment values are in order, as I have them in my data list, on the camera.

Was confident it registered the 40-150 + mc-14 ok, because it shows as 56-210mm.
When proceed into the 'check' screen for 56-210mm, it shows the focal length + serial number of the 40-150mm but has added an 0A on the end ! ( S/N ABV****330A) presume this is recognition of the MC-14.


Mark

super_claret
22nd October 2017, 08:51 AM
I wonder if someone could explain step by step how to adjust for back focus. Just got the 40-150 f2.8 PRO and was photographing pheasants yesterday and focusing on the eye/head but they all came out soft. The breast of the pheasant was pin sharp though!

Is it worth sending the lens back and asking for a replacement, as I hired the same lens a few months ago and had no issues with focusing accuracy?

Thanks in advance.

DanC.Licks
22nd October 2017, 09:10 AM
It is important to realize that that could have nothing to do with front/back focusing. The AF sensors are out for contrast edges, and they are more abundant in feathers than around the eye. The only way to find out whether the lens/camera is really front or back focusing, which I seriously doubt given the nature of the system, is with a dedicated AF fine tuning chart. Can also make one yourself. No need to buy anything.
Important to know also which AF points were selected. Single point is the only way to really select the focus point. Give the camera more choices and it will go for whatever it thinks is best. I have the 300/4 Pro, and there are times when I want the eye and get feathers instead, but it is always with 5 or 9 points selected. Single point is the way to go on static subjects. On the focus fine tune chart it is bang on.
Here is an example from the other day:
https://c1.staticflickr.com/5/4483/37817933762_7d9cc9c269_b.jpg
Took care to get the focus point right on the eye. The feathers on the shoulder are much more attractive for the AF system, and at that distance, even a single AF point can be problematic.

super_claret
22nd October 2017, 09:18 AM
Thanks for the reply Dan. It's weird because I don't have these issues with the 300mm f4. When positioning the focus point on the birds eye/head, there was plenty of contrast in that region.

I'll obviously have to do some more tests.

DanC.Licks
22nd October 2017, 09:23 AM
Naturally with 300mm you will be able to be more selective.
That all said, it is strange that you had no issues with the hired lens. However, lighting conditions and subject mater play a HUGE role in AF, so it is hard to compare unless you have both side by side.

Here is one with the 300 without the MC-14, stopped down to 5.6. It is an ideal situation because the eye and the shoulder are on the same plane.
https://c1.staticflickr.com/5/4493/37349110280_e66b60f61d_b.jpg
Even so, we are talking millimeters here, and the feathers just a tad closer are no longer sharp.
Full sized here:
https://c1.staticflickr.com/5/4493/37349110280_eea25a3f11_o.jpg

GyRob
22nd October 2017, 10:01 AM
I agree, Dan has it spot on imho .
For my checking I use a cereal box at about the distance I use with that lens i.e 300mm around 70 ft this gives a clear indication I am at leased at the longer side of how I use it and this will also cover far longer shots too .
If I only shot birds in a tree then I would set the test target at about 30ft .


Rob.

DanC.Licks
22nd October 2017, 10:25 AM
On top of that, we have to keep in mind that with distance comes air, and air is EVIL! AF systems hate it, and the more there is between us and our subjects, the more they complain.;)

Tordan58
14th December 2018, 02:45 PM
Hi,

I know this is a fairly old thread. Anyway I wanted to share a useful and understandable post from DP Review which I came across in search of other information. That post touches on the pros and cons of PDAF vs. CDAF and then the necessity of tuning (or at least checking) the focus adjustment for 4/3 lenses and how to do so when using the EM-1.1. I think the method should be the same for the EM1.2 as the user interface has not changed.



The post is found here:
https://www.dpreview.com/forums/post/60174208
(https://www.dpreview.com/forums/post/60174208)