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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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  #16  
Old 19th April 2018
TonyR TonyR is offline
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Re: C-AF - tight/loose

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Originally Posted by Growltiger View Post
We do know, as I did extensive testing. It is a delay as you guessed, and I measured it at all the settings. See my message #6 above.

If you are following a moving object you may lose it for a moment. If you have a lower setting such as -1 the focus won't change for a moment, so you may get the object in your aim again before the focus starts changing. That is the idea. (But I use +2 like you do.)
That's not quite what I meant. Your test shows that there is a delay when you deliberately move the camera between subjects at different distances. That is not something that I try to do in my photography.

What I try to do is keep the focus point on the subject. And when I do that successfully, and the subject is moving, does the C-AF Sensitivity setting have any effect on the accuracy of the AF? That is what we don't know and your test doesn't say anything about that. Some people say that +2 works better than other settings in this scenario but I don't find any difference.
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  #17  
Old 19th April 2018
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Re: C-AF - tight/loose

It did change: I find tight and loose helpful brief descriptors and more meaningful than +\- (plus or minus what?). Others disagree, I know.

About half way down this page there’s a helpful table: http://asia.olympus-imaging.com/prod...2/feature.html
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  #18  
Old 19th April 2018
Growltiger Growltiger is offline
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Re: C-AF - tight/loose

Here are the actual timing delays controlled by the setting. This is copied from the forum I originally posted it to.

Results of timing measurements

I worked out a way to measure the C-AF Sensitivity setting delay with reasonable accuracy. I moved the camera quickly between near and far, running bursts at 18fps. I then subtracted the zero delay focus times (it takes the camera and lens I was using 0.28s to adjust focus with this setup). The results are as follows. The delay is expressed in hundredths of a second.

Sensitivity ----- Delay in 1/100 of a second ----- Frames at 18fps
+2 ----- 0 ----- 0
+1 ----- 5 ----- 1
0 ----- 17 ----- 3
-1 ----- 67 ----- 12
-2 ----- 117 ----- 21

This seems to fill in the gap in what Olympus tell us. It helps us understand what each setting does.

I found it very interesting to see that there is a steep curve here, as you head from high to low. The small delay with +1 grows hugely as you head to -1, and the delay with -2 is over a second.
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  #19  
Old 19th April 2018
Growltiger Growltiger is offline
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Re: C-AF - tight/loose

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Originally Posted by drmarkf View Post
It did change: I find tight and loose helpful brief descriptors and more meaningful than +\- (plus or minus what?). Others disagree, I know.
Sensitivity. The feature is now called C-AF Sensitivity and the settings are marked High and Low. So +2 is the highest sensitivity and -2 is the lowest sensitivity.
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Old 19th April 2018
Growltiger Growltiger is offline
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Re: C-AF - tight/loose

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Originally Posted by TonyR View Post
That's not quite what I meant. Your test shows that there is a delay when you deliberately move the camera between subjects at different distances. That is not something that I try to do in my photography.

What I try to do is keep the focus point on the subject. And when I do that successfully, and the subject is moving, does the C-AF Sensitivity setting have any effect on the accuracy of the AF? That is what we don't know and your test doesn't say anything about that. Some people say that +2 works better than other settings in this scenario but I don't find any difference.
The deliberate change between near and far was designed to simulate having the focus point on a subject and then failing to keep the focus point on the subject. None of us try to do that, we try to do the opposite.

I share your view that this setting has no effect on the AF accuracy, except that in various scenarios where you lose and then regain the subject, the delay may help or hinder. As you say I can't prove it.
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Old 19th April 2018
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Re: C-AF - tight/loose

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Originally Posted by Growltiger View Post
Sensitivity. The feature is now called C-AF Sensitivity and the settings are marked High and Low. So +2 is the highest sensitivity and -2 is the lowest sensitivity.
Fair enough: on the other hand, before it would hang on 'tight' to the subject, which is what I'd got used to.

I guess either would have done had they explained it better beforehand, in which case the change would have been unnecessary and confusing.
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Old 19th April 2018
GyRob GyRob is offline
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Re: C-AF - tight/loose

Iv had success with all of the settings same with my 1DXMK II but I do find +2 can make the camera feel a little jiterish / jumpy because it can react quicker than I can
Note I'm only talking about bird photography.
- 2 is the opposite it makes the camera feel slow/sluggish for me I'm finding +1 is just about right mixed with Bumping the shutter button that is to say taping the shutter to make the camera re focus .
No one setting is perfect there isn't one it's just finding what works best for how quick your reaction time is .
someone new to birding may well find -1 is a good starting point .
I do use the 300f4 pro and have the limiter set so its not going to hunt that too helps a lot.
Rob.
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  #23  
Old 20th April 2018
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Re: C-AF - tight/loose

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Originally Posted by GyRob View Post
Iv had success with all of the settings same with my 1DXMK II but I do find +2 can make the camera feel a little jiterish / jumpy because it can react quicker than I can
Note I'm only talking about bird photography.
- 2 is the opposite it makes the camera feel slow/sluggish for me I'm finding +1 is just about right mixed with Bumping the shutter button that is to say taping the shutter to make the camera re focus .
No one setting is perfect there isn't one it's just finding what works best for how quick your reaction time is .
someone new to birding may well find -1 is a good starting point .
I do use the 300f4 pro and have the limiter set so its not going to hunt that too helps a lot.
Rob.
Yes, I've settled on +1 as well for BIF for exactly that reason (with -2 for birds in reeds and branches if there's time to change the setting) and mostly left on 0 otherwise.

I haven't yet tried motorsports or rugby (the other 'fast motion' shooting subjects I most often do) since the latest update, but now we've got a clearer idea about what the settings do it should be easier to work out which works best for people's particular styles.
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  #24  
Old 23rd April 2018
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Re: C-AF - tight/loose

I only use C-AF and I’m almost sure the sensitivy factor does take effect. Those pictures are taken at 0, and shows the camera maintaining the focus even in very challenging scenes with birds flying across the trees.
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  #25  
Old 23rd April 2018
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Re: C-AF - tight/loose

I agree - for the starkest demonstration, try following a duck paddling between fairly sparse reeds using CAF and single point (or 5 or 9), first at -2 and then at +2.

At the former setting it will hang on to the animal well (as long as it has got decent contrasting feather detail). On +2 it'll dart around all over the place between reeds and the duck.

That's my experience, anyway.
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Too much Oly gear.
Panasonic 12-35, 15. Samyang 7.5 fisheye. Laowa 7.5.
Assorted legacy lenses, plus a Fuji X70.
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