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Old Apr 11, 2014, 7:55 AM   #1
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Default CAF Accuracy .. whats an acceptable rate ?

This weekends the annual London Marathon and Basiakhi (Important day in the Sikh calendar), and I'm planning on being in town to capture the runners. Hopefully, I'll get to see and snap Mo Farah leading the pack on Sunday and hopefully see one of my old friends complete the run for the first time if I get there early enough and the same spot as before.

Now the question is CAF accuracy, I've been going thro the last 2 years worth of sports related pics and prior to Hockey tournement a couple of weeks ago, it looks as if the E3's CAF tracking ability is on average approx 20% when tracking someone come at you fast and head on. Thats critically sharp images and with the 35-100F2.. I've not tested it with the 14-54 so I don't know if the smaller lens would be any better. Changing to all 12 AF points, seems to have improved that hit rate a bit more but only by another 10%.

Is a 20%-30% CAF tracking accuracy rate acceptable (excluding user error) ?
Whats the tracking accuracy of the OMD-EM1 with native M43 lenses ?
Whats the tracking accuracy of the OMD-EM1 with FT lenses ?
Is the E5's CAF tracking any better than the E3's and if so by how much?

What made me think about the CAF was this vid of the D4s:


I know its a brand new cam and designed for action .. but look at how accurate the cam is .. 90%+ at achieving critically sharp images. The 1DX is even more accurate from another vid that I've recently seen. I saw the pics that the Pro shooter took with the D300s and his accuracy at the Hockey tournement is 70% or higher and thats from a cam the same age as the E3.

Last edited by HarjTT; Apr 11, 2014 at 8:57 AM.
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Old Apr 11, 2014, 11:05 AM   #2
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Hi Harj, that is an interesting question. My shooting style and subjects are different from yours, so I can't really compare. But I get a pretty high hit rate with the E-3 and 50-200 shooting flying jets at air shows, and the race cars at NASCAR races. I've never shot the kind of events that you cover. However, I have followed some of the micro-4/3 forums and there are lots of impressive action shots using the M-1. Here on Steve's-Digicams Oly Micro 4/3 forum, TG from Australia uses the M-1 on Formula One races, air shows, and motorcycle races, and he has very impressive action shots, many where the subject is coming straight at him. Ramcewan had mentioned this in a previous post here:

Originally Posted by Ramcewan
From what I am seeing out of the EM-1 by the likes of TG I would say an EM-1 w/the lumix 35-100 f2.8 can do the same job as the D300 plus 70-200VR f2.8. You've got useable C-AF, fast burst rate and the WiFi to transfer to a computer in real time, touch up and put up for sale after the show.

You may be interested in some of TG's shots:

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Old Apr 11, 2014, 2:09 PM   #3
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Hi Hartj,

With the Canon 5D III that is 96% and Nikon D800 92%.
So When you compare to the E-3 then I must think not normal.
But isn't so that when you use a battery grip that the % also raises with the E-3?
One photo out of focus is a mistake, ten photo out of focus are an experimentation, one hundred photo out of focus are a style.

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Old Apr 11, 2014, 3:44 PM   #4
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Hey Steve/Pascal

Steve, those are some pretty fine pics with the EM1 .. in between studying today (i'm finding it hard t o step away from it atm) I came across the following link for AF accuracy and the EM1 with FT lenses:


Its a pretty good read. I did find another site that did extensive testing with the EM1 and SHG's but I lost the link and googles been crap at finding it again.

Now back to the E3 - I decided to check what settings the pro sports photographers were using for their Canikons:

1. Focus and Release Priority

A really good read :


A first for me a Ken Rockwell quote:

"The default is "Release Priority." The D70 and D50 only work in this mode.
In default Release Priority mode, Nikons fire anytime you press the shutter. They fire even if they're not in focus. If you're shooting a sequence, most of the shots except for the first two will be out of focus!"

So that would explain why the E3 would fire the shutter even when nothing is in focus, although in my case .. its usually none of the pics can be in focus!

I had Release Priority for CAF set to On - so may be it should set to OFF
New D7100 lets me take photos when out-of-focus, help needed.
2. The back focus button for AF- I know I was supposed to test this out and I think I should but with the BG on the cam I don't know how you can map the AEL/AF button to the BG.


I've swapped the AEL/AF and FN buttons so that I can use the BG in portrait mode and use the back focus.

3. C-AF Lock - should be off .. and thats what i had it on


4. CAF- Modes - Mine was set to default mode 2 but I've switched it Mode 3

"CAF Mode 2: AF starts when the release is half-pressed; then both AF and AE are adjusted till the last moment, unless the lock button is used to freeze the exposure. This is the default. "

Now I've been reading that Mode3 or 4 provide a better keeper rate
  • CAF Mode 3: Half-pressing the release freezes the exposure; continuous AF (or any AF) is active only when the lock button is being held down. Once again, this becomes a manual focus mode with continuous AF "on demand", like SAF Mode 3 above.
  • CAF Mode 4: Like CAF Mode 3, except that the exposure is being adjusted up to the last moment. Like in Mode 3, continuous AF is performed only while the lock button is held down.
5. Burst rate - 5fps or 4pfs ?


hadn't thought that the burst rate could impact no of in focus images but its looking as it can with Olys - 4fps produces a higher number of in focus images.

Whats surprising is that after all these years theres no definitive set of settings for the E-3/E-5 !!

I did come across this link for the Nikon D3


Pascal .. where I have used the BG .. its improved .. I think all thats happening there is theres more power and thats it. The old oly grip doesnt do what the Nikon/Canon grips do which is also improving the AF.

I'm going to attempt some tests tomorrow and see how i get on b4 Sunday.

Last edited by HarjTT; Apr 11, 2014 at 3:57 PM.
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