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Olympus OM-D E-M1 The first 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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  #76  
Old 26th March 2015
kbouk kbouk is offline
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Re: 15 frame sequence E-M1 BIF after firmware update

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Originally Posted by DavyG View Post
The 37 focus points appear when using a 4/3 lens.

I think I understand this correctly however, I'm happy to be corrected if my understanding is wrong.

Dave
Unfortunately you are wrong but it's not so obvious to understand it,
on CAF - H mode (9fps) the 37 focus points area appears and is in use when using all 4/3 and m43 lenses (because this is the only area with PDAF focus points) when you hit the shutter button,
before the press of the shutter with m43 lens you can choose from the bigger area of 81 point grid but when CAF on Sequental H engage only the 37 points are in use and you have to try to keep target inside this limited area, only with CAF on Sequental L (up to 6.5fps) all 81 points are in use because there the focus is a mixed CDAF+PDAF.
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  #77  
Old 26th March 2015
DavyG DavyG is offline
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Re: 15 frame sequence E-M1 BIF after firmware update

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Originally Posted by kbouk View Post
Unfortunately you are wrong but it's not so obvious to understand it,
on CAF - H mode (9fps) the 37 focus points area appears and is in use when using all 4/3 and m43 lenses (because this is the only area with PDAF focus points) when you hit the shutter button,
before the press of the shutter with m43 lens you can choose from the bigger area of 81 point grid but when CAF on Sequental H engage only the 37 points are in use and you have to try to keep target inside this limited area, only with CAF on Sequental L (up to 6.5fps) all 81 points are in use because there the focus is a mixed CDAF+PDAF.
Thanks for your post.

This has thrown up an interesting point in that, I understood that when using C-AF on seq H only the area within the 37 focus points uses PDAF however, if the point of focus strays outside this area when using m43 lenses, the camera will continue to attempt to focus using CDAF only, the update document states:

When shooting in C-AF mode, the camera uses 37 AF point, phase-detection autofocus (PDAF). Figure 1, image 1, shows the actual locations of the 37 AF target points. While you are actually firing the camera in Sequential H burst mode, you will see a faint focus area frame in the EVF or monitor, outlining the 37 AF point area (figure 1.0, image 2). In other words, the camera will autofocus using the outlined area seen in image 2, all the time you are holding down the shutter button and firing the burst of images.

The E-M1 provides phase-detection autofocus in C-AF mode, with both Micro Four Thirds and older Four Thirds lenses. It uses 37 of the 81 available focus points because only the 37 points have on-chip, phase- detection capability (figure 1, image 1). If you allow the subject to stray outside of the framed area seen in figure 1, image 2, it will no longer use phase-detection (PDAF) autofocus. Instead it will use contrast-detection (CDAF) autofocus, which may not be as efficient at updating the focus with a rapidly moving subject.

In addition, when I use a 4/3 lens only the 37 point focus grid is seen on the monitor and the 37 point area is clearly visible in the EVF however, when using any of my m4/3 lenses the 81 point grid remains visible regardless of whether the shutter is pushed or not and all I see in the EVF is the selected point of focus, the 37 point PDAF area does not appear.

I'd be interested to hear of other E-M1 users experiences as there may be an error in the way the information is being interpreted.

Dave
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  #78  
Old 27th March 2015
TonyR TonyR is offline
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Re: 15 frame sequence E-M1 BIF after firmware update

It seems to me that the E-M1 with a micro 4/3 lens does a strange combination of focus techniques. During the initial focus acquisition, when you are half-pressing the shutter, it seems to use the old combined method of PDAF and CDAF. This is not very good and can end up hunting all over the place. It shows the 81-areas if you have all areas selected and will resort to CDAF only if the subject moves out of the 37-area PDAF array. I think this behaviour is the same as all previous pre-version 3.0 firmwares.

Where version 3.0 is different is once you start shooting in sequential H mode. Once shooting starts, C-AF switches to PDAF only and consequently shows the outline of the 37-area PDAF array. C-AF is quite good provided the starting point left be the initial acquisition described above is reasonably close. AF is very accurate and tracking quite good. I don't know what happens if the subject strays out of the 37-area PDAF array.

The comments above are my deductions and not facts. As an ex-software guy, this is what I would call a hack. Instead of leaving the focus static during the sequential-H shooting part of the process, the software calls up the PDAF focus routine to change focus between shots. It works remarkably well. But it's still a hack to the sequential-H routine. This is why the behaviour of C-AF during the initial focus acquisition is unchanged and why there is no change to sequential-L.

I would like Olympus to use the experience gained from firmware 3.0 to completely revise all the C-AF operation with micro 4/3 lenses so that it use PDAF only at all times except when the subject is outside the 37-area PDAF array. Then they could dump Sequential H and Sequential L and just have Sequential because there would be no difference!
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Old 27th March 2015
kbouk kbouk is offline
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Re: 15 frame sequence E-M1 BIF after firmware update

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Originally Posted by TonyR View Post
I would like Olympus to use the experience gained from firmware 3.0 to completely revise all the C-AF operation with micro 4/3 lenses so that it use PDAF only at all times except when the subject is outside the 37-area PDAF array. Then they could dump Sequential H and Sequential L and just have Sequential because there would be no difference!
I agree with all your observations but I'm afraid your final conclusion - proposal needs more explanation, there are two more differences between the two modes (H an L): fix exposure at the first frame and the absence of the liveview on H mode (because there isn't enough processor power to handle them compare to the L mode), Olympus must combine the best of the two modes (i think we will see it in the next E-M1 II).
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Old 27th March 2015
TonyR TonyR is offline
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Re: 15 frame sequence E-M1 BIF after firmware update

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Originally Posted by kbouk View Post
I agree with all your observations but I'm afraid your final conclusion - proposal needs more explanation, there are two more differences between the two modes (H an L): fix exposure at the first frame and the absence of the liveview on H mode (because there isn't enough processor power to handle them compare to the L mode), Olympus must combine the best of the two modes (i think we will see it in the next E-M1 II).
Good point(s)! It isn't really necessary to merge the two modes. I was getting ahead of myself. They should make C-AF using PDAF consistent across all modes though.
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