Clarification on technicalities of fixing Oly CAF issues

Started Oct 18, 2012 | Discussions
agogo Contributing Member • Posts: 603
Clarification on technicalities of fixing Oly CAF issues

I'd like to pose some questions to those less technically challenged than myself (seems to be more than a few lurking here on this forum), so that I might have a better understanding of how hard the CAF problems are to correct with the 4/3 system.

The CAF seems to be the biggest issue with 4/3 users on these forums - or maybe it's the higher ISO/sensor performance - not sure, but it's certainly one of the main frustrations expressed on this forum.

I'd like to know if accurate and fast CAF is even possible to achieve on the 4/3's system at all.

The SWD lenses would have the best chance I'm guessing, but the non-SWD lenses, in particular, I'm interested in (because I have the old 50-200 and 300/2.8) with their slower focusing motors.

How much of the CAF speed/accuracy is based on digital processing as opposed to the PDAF sensors and mechanical focus motors/system?

Is it more a PDAF sensor problem?

If Oly had quicker processing and better algorithms for CAF, would this fix the problem?

I'd imagine that the processing would have to take info from the AF sensors then predict the speed and direction of the object, then send that info to the focus motor - all within a nano-second.

If there were better processing and PDAF sensors, would the focus motor and the rest of the mechanical focus system still be capable of keeping up? Or is it all too dated and sluggish?

It seems to be an unsolvable problem for Oly - even with the CDAF on m4/3.

I will say though, that it's not totally unusable - I have been able to get BIF keepers with my Oly gear.

Thanks in advance for the enlightenment

OM 6Ti Plus Contributing Member • Posts: 756
Re: Clarification on technicalities of fixing Oly CAF issues

agogo wrote:

I'd like to pose some questions to those less technically challenged than myself (seems to be more than a few lurking here on this forum), so that I might have a better understanding of how hard the CAF problems are to correct with the 4/3 system.

The CAF seems to be the biggest issue with 4/3 users on these forums - or maybe it's the higher ISO/sensor performance - not sure, but it's certainly one of the main frustrations expressed on this forum.

I'd like to know if accurate and fast CAF is even possible to achieve on the 4/3's system at all.

Quite possibly not; if it was easy Olympus' engineers would have done it by now :). I would say it is more to do with Newton's First Law (of Motion) and the mass of the focus group, plus the tolerances of the AF system. I doubt there is much chance of firmware fixes solving the problem. My lay opinion is that the focus groups of the lenses, as designed, are too massy for fast response CAF, but I am not a lens designer.

Mike

surfingmaltman Regular Member • Posts: 185
Re: Photo Albums using OLY CAF

https://www.facebook.com/pages/Surfing-Newcastle/123837104358786?sk=photos_albums

All using Oly E3 and EC20 coupled to 50-200mm SWD.

Hoep that helps to see what is possible. They are not BIF but do use CAF.

Rich

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alatchin Senior Member • Posts: 1,055
Re: Clarification on technicalities of fixing Oly CAF issues

Just a quick note... I dont think it is speed of acquisition that is holding it back... so they can move fast enough (remember all of these lenses are relatively new designs) but the systems ability to follow or predict.

Better PDAF sensor, processing and algorithms will improve its overall performance.

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philosomatographer
philosomatographer Contributing Member • Posts: 539
Re: Clarification on technicalities of fixing Oly CAF issues

Considering the medium focusing speed of the two SHG Zuikos I have, the 7-14mm and the 35-100mm, I have to think that the raw speed at which the focus plane moves is fast enough for tracking most conceivable subjects. The primary problem is surely in the camera hardware/software - specifically the ability to acquire and keep up with the rate of change of the position of the object being tracked.

I am hopeful that it can be solved. The lenses are extremely modern - pity as it is that they do not all feature ultrasonic motors. In fact, Olympus must be the only company in the world whose medium-range lenses feature more ultrasonic motors than their professional range, with the 14-35 being the lone SHG lens with an ultrasonic motor.

If Nikon can do pretty good focus tracking even with lenses with no built-in focus motor (screw-driven 1980s lenses) it must be possible with the modern range of Zuikos in theory at least

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goblin
goblin Veteran Member • Posts: 3,539
Re: Clarification on technicalities of fixing Oly CAF issues

agogo wrote:

...

The CAF seems to be the biggest issue with 4/3 users on these forums - or maybe it's the higher ISO/sensor performance - not sure, but it's certainly one of the main frustrations expressed on this forum.

I'd like to know if accurate and fast CAF is even possible to achieve on the 4/3's system at all.

Definitely yes. There is no reason not to. All the elements needed for that, as far as lenses are concerned, are present.

The SWD lenses would have the best chance I'm guessing, but the non-SWD lenses, in particular, I'm interested in (because I have the old 50-200 and 300/2.8) with their slower focusing motors.

Again - yes, shouldn't be that much of a problem.

How much of the CAF speed/accuracy is based on digital processing as opposed to the PDAF sensors and mechanical focus motors/system?

A good part of it.

Is it more a PDAF sensor problem?

In part, yes. The more (as long as there's enough electronic brain behind to fully use them) - the merrier. Then again, in the case of the E-3/30/5 the sensors do a great job and are made the right way.

If Oly had quicker processing and better algorithms for CAF, would this fix the problem?

It would greatly improve things.

I'd imagine that the processing would have to take info from the AF sensors then predict the speed and direction of the object, then send that info to the focus motor - all within a nano-second.

Don't know if it's in a nanosecond, but that's already what it does.

If there were better processing and PDAF sensors, would the focus motor and the rest of the mechanical focus system still be capable of keeping up? Or is it all too dated and sluggish?

Without being a specialist, I believe that they will keep up very very well.

It seems to be an unsolvable problem for Oly - even with the CDAF on m4/3.

No, just a matter of available money and the decisions about where to put it.

I will say though, that it's not totally unusable - I have been able to get BIF keepers with my Oly gear.

I don't know what your gear is, but I have to say that the E-5 is totally adequate for BIF in most of the cases. There are a few things to consider:

- Amazing as it sounds and contrary to the legend, C-AF works very well on the E-5 (I used to have the E-30 and the E-3, but that was before I bought my 50-200mm so I never had the chance to compare apples to apples), .

By this I mean that when you do little tests to see how your C-AF works, there are always little disappointments. Get in the heat of the action, start shooting - very soon you will be so deep into it, that you will even forget what AF mode you're in. Get home, dump your files on your computer, and you will be surprised by the amount of keepers you'll get.

At least, that's the case for me.

One other thing - I don't know exactly how BIF professionals with big rigs, gimbal heads and whatnot proceed, but i am personally more limited following a BIF in my viewfinder at 400mm when it's filling my whole viewfinder, rather than by anything else.

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goblin
goblin Veteran Member • Posts: 3,539
Re: Clarification on technicalities of fixing Oly CAF issues

Edit window expired - here's to illustrate the "​" part:

Here's an example of what I'm talking about. Sorry for the numerous images, but it's to illustrate my point:

Those are not all the frames from the burst, just every other one so I don't pollute the thread.

The camera even managed to misfocus this one:

Then catch up on the next:

That's with an E-5 + EC14 + 50-200mm SWD.

As you can see, the camera was not to blame. It adapted, focused, followed. It's the device behind the camera which messed up

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goblin
goblin Veteran Member • Posts: 3,539
Re: Clarification on technicalities of fixing Oly CAF issues

There seems the be a bug adding the pictures, will add tomorrow if they don't pop up within the hour.

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OP agogo Contributing Member • Posts: 603
Re: Clarification on technicalities of fixing Oly CAF issues

I know the CAF can work, even on the E3 - I have some great BIF shots, but it isn't consistent and the keeper rate isn't great. I know the E5 performs a bit better than the E3 in this regard and it works better without the EC's.

Another thing that would help is more FPS - like 7-9 FPS would be great.

surfingmaltman Regular Member • Posts: 185
Re: Clarification on technicalities of fixing Oly CAF issues

goblin wrote:

Edit window expired - here's to illustrate the "​" part:

Here's an example of what I'm talking about. Sorry for the numerous images, but it's to illustrate my point:

Those are not all the frames from the burst, just every other one so I don't pollute the thread.

The camera even managed to misfocus this one:

Then catch up on the next:

That's with an E-5 + EC14 + 50-200mm SWD.

As you can see, the camera was not to blame. It adapted, focused, followed. It's the device behind the camera which messed up

Have to agree with your last line here goblin.

That's why I posted the site above with lots of images.

Sure they are not BIF but i am using the E3 with EC20 and shooting at f11. No go territory?

I agree that the e3 is not the best out there when it comes to CAF and I think my experience is limited to surfing but I think that goblin makes a good point about user technique being a considerable factor in OOF images.

More fps would be nice but 4 is ok.

Rich

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JoopN Regular Member • Posts: 151
Re: Clarification on technicalities of fixing Oly CAF issues

I'm not sure, but as far as I learned it has to do with how you did setup your camera. One thing for sure, you can do mess up more in settings then with other systems. So it might be a setup problem. Also there are some sites with "how to's" and I learned there that if you want to catch birds or planes in flight its best to set up with all focus elements and not with diamond or one.

goblin
goblin Veteran Member • Posts: 3,539
Re: Clarification on technicalities of fixing Oly CAF issues

goblin wrote:

There seems the be a bug adding the pictures, will add tomorrow if they don't pop up within the hour.

Ok, last try from the DPR galleries this time, if it doesn't work - I give up

This one is to give an idea where I am and how far relative to the bird in flight

You can see that as it comes from the side, the distance to the subject becomes smaller and smaller.

Then, the subject comes to its closest point. At this time, it fills almost my whole viewfinder, and this is where the DBTC (Device Behind The Camera) craps out:

Then the camera had the time to misfocus one, and to refocus for the next one:

As for bursts - might not be the best, but my friend next to me with a d300s and a d7000 simply gave up trying. He was already pretty p#ssed with his 80-400mmVR anyway.

There's always worse (although conditions were pretty crappy and the 80-400mmVR is known to be slow to focus).

PS sorry if some photos double, I have a crap of a time selecting on those tiny thumbnails.

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illy
illy Forum Pro • Posts: 12,160
Re: Clarification on technicalities of fixing Oly CAF issues

goblin wrote:

 As for bursts - might not be the best, but my friend next to me with a d300s and a d7000 simply gave up trying. He was already pretty p#ssed with his 80-400mmVR anyway.

There's always worse (although conditions were pretty crappy and the 80-400mmVR is known to be slow to focus).

PS sorry if some photos double, I have a crap of a time selecting on those tiny thumbnails.

the 80-400mm is a screw drive lens, get a nice AF-S lens he'd have no problems

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goblin
goblin Veteran Member • Posts: 3,539
Re: Clarification on technicalities of fixing Oly CAF issues

illy wrote:

the 80-400mm is a screw drive lens, get a nice AF-S lens he'd have no problems

I know. I used to have it.

Yet - the 80-400mm gave me great results at motocross races with the D200, on a nice day with the sun in the right position.

Light at that airshow was simply awful - strong sun, but a lot of humidity and some sort of mist through which the sun had to filter, and positioned at a pretty bad angle (almost always in the field, except at the end of the day).

I also had my E-M5 + 75-300mm with me, and it had great difficulties locking on anything, same for my friend with his Nikon gear which I otherwise love.

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illy
illy Forum Pro • Posts: 12,160
Re: Clarification on technicalities of fixing Oly CAF issues

goblin wrote:

illy wrote:

the 80-400mm is a screw drive lens, get a nice AF-S lens he'd have no problems

I know. I used to have it.

Yet - the 80-400mm gave me great results at motocross races with the D200, on a nice day with the sun in the right position.

Light at that airshow was simply awful - strong sun, but a lot of humidity and some sort of mist through which the sun had to filter, and positioned at a pretty bad angle (almost always in the field, except at the end of the day).

I also had my E-M5 + 75-300mm with me, and it had great difficulties locking on anything, same for my friend with his Nikon gear which I otherwise love.


you should try airshows in the UK for bad light, to even see the sun would be a nice thing in the summer, some of the shutter speeds you use for fast jets are more appropriate for props, time to try somewhere sunny next year

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d3xmeister Veteran Member • Posts: 3,380
Re: Clarification on technicalities of fixing Oly CAF issues
2

Like it was said and proved many times here, Olympus C-AF really works great with the right settings techniques. I've done it even with the E-620 and 40-15mm MKII with good results, but with the E-5 and the 35-100 it was superb.

I want to add that I also used briefly the E-5 with grip and the 50-200 SWD and it was the fastest AF performance I have ever saw. It was like lightning, a Nikon D3 with 70-200mm seemed very slow by comparison. The only combination I used that seems to compete is the Canon 1DX with the 70-200mm IS II. You don't believe me, try it. A side note, for different reasons I use Nikon gear now.

So here's how I set up my E-5 with 35-100mm for C-AF work:

- Always use the HLD-4 original grip, in my experience it makes a big difference.

- Don't use batteries with less than 35% power in them. When you see the first drop form 2 lines to 1, change both batteries. This is from experience. One day I found the C-AF to work poorly, it took me some time to find out what was causing this, it was the batteries. I was able to duplicate this behaviour. So always use fresh charged batteries in the grip.

- Always use Dynamic Area AF (you can select it by pressing AF and rotate the front dial). It uses your selected point, but gets help from adjacent points. Be aware that it does not change the area or point like Nikon. Always keep your subject under the focus point for good results. Works much better than single points. NEVER EVER EVER use 11-points, it does not work at all and the AF is very slow in this mode, even on SAF.

- Set CAF Lock to ON in the menus. Everybody say this should be set to OFF, but it's WRONG. I tested this and CAF Lock ON works much, much better in every single CAF situation I tested, especially for fast moving subjects. From what I saw, the camera is hesitant to change focus by much if this is set to OFF, coupled with the slow 5fps. I repeat, set this to ON before you cry the E-5 cannot C-AF.

- Something that makes a hell of a difference: Wait for the camera to catch up with the subject before releasing the bursts. The camera takes some time from the moment you put your focus point on the subject and half press, starts tracking...to the moment it locks on the subject. Use the viewfinder and try to understand when the camera has caught up with the subject. It doesn't take long, and it's easy to do/see. Just be aware of this.  IMPORTANT: If you release the bursts before the camera caught up, your sequence will be ruined.

- Something that sometimes improves  keeper rate in some very difficult conditions: Shoot quick short bursts, keeping your finger half-pressed. So, cameras starts tracking the subject - release quick short burst - release the shutter to half way for a fraction (camera continues tracking) - release quick short burst

I hope I haven't forgot anything, I haven't used Olympus gear from 2011 :), but using what I described above, the E-5 was a superb tracking machine, my keeper rate was always around 95-100%.

Also important: The Olympus AF is sloooooooow and unreliable in low-light. All above work in daylight or very good artificial light. So if you want to track your kids indoors, or a sport event indoors/low light, or very low contrast scene, Olympus AF is falling apart (one of the reasons I switched)

Maybe that is a better subject for a new topic: Why Olympus AF is so bad in low light ?

d3xmeister Veteran Member • Posts: 3,380
Re: Clarification on technicalities of fixing Oly CAF issues

d3xmeister wrote:

Like it was said and proved many times here, Olympus C-AF really works great with the right settings techniques. I've done it even with the E-620 and 40-15mm MKII with good results, but with the E-5 and the 35-100 it was superb.

I want to add that I also used briefly the E-5 with grip and the 50-200 SWD and it was the fastest AF performance I have ever saw. It was like lightning, a Nikon D3 with 70-200mm seemed very slow by comparison. The only combination I used that seems to compete is the Canon 1DX with the 70-200mm IS II. You don't believe me, try it. A side note, for different reasons I use Nikon gear now.

So here's how I set up my E-5 with 35-100mm for C-AF work:

- Always use the HLD-4 original grip, in my experience it makes a big difference.

- Don't use batteries with less than 35% power in them. When you see the first drop form 2 lines to 1, change both batteries. This is from experience. One day I found the C-AF to work poorly, it took me some time to find out what was causing this, it was the batteries. I was able to duplicate this behaviour. So always use fresh charged batteries in the grip.

- Always use Dynamic Area AF (you can select it by pressing AF and rotate the front dial). It uses your selected point, but gets help from adjacent points. Be aware that it does not change the area or point like Nikon. Always keep your subject under the focus point for good results. Works much better than single points. NEVER EVER EVER use 11-points, it does not work at all and the AF is very slow in this mode, even on SAF.

- Set CAF Lock to ON in the menus. Everybody say this should be set to OFF, but it's WRONG. I tested this and CAF Lock ON works much, much better in every single CAF situation I tested, especially for fast moving subjects. From what I saw, the camera is hesitant to change focus by much if this is set to OFF, coupled with the slow 5fps. I repeat, set this to ON before you cry the E-5 cannot C-AF.

- Something that makes a hell of a difference: Wait for the camera to catch up with the subject before releasing the bursts. The camera takes some time from the moment you put your focus point on the subject and half press, starts tracking...to the moment it locks on the subject. Use the viewfinder and try to understand when the camera has caught up with the subject. It doesn't take long, and it's easy to do/see. Just be aware of this.  IMPORTANT: If you release the bursts before the camera caught up, your sequence will be ruined.

- Something that sometimes improves  keeper rate in some very difficult conditions: Shoot quick short bursts, keeping your finger half-pressed. So, cameras starts tracking the subject - release quick short burst - release the shutter to half way for a fraction (camera continues tracking) - release quick short burst

I hope I haven't forgot anything, I haven't used Olympus gear from 2011 :), but using what I described above, the E-5 was a superb tracking machine, my keeper rate was always around 95-100%.

Also important: The Olympus AF is sloooooooow and unreliable in low-light. All above work in daylight or very good artificial light. So if you want to track your kids indoors, or a sport event indoors/low light, or very low contrast scene, Olympus AF is falling apart (one of the reasons I switched)

Maybe that is a better subject for a new topic: Why Olympus AF is so bad in low light ?

I missed a important setting: Set RLS Priority to OFF for CAF.

Also, I think it helps to shoot in full Manual mode and a preset White Balance. The camera doesn't have to process exposure and WB leaving all processing power for AF calculations.

Ulfric M Douglas Veteran Member • Posts: 4,828
Re: Clarification on technicalities of fixing Oly CAF issues

d3xmeister wrote:

d3xmeister wrote:

- Always use the HLD-4 original grip, in my experience it makes a big difference.

- Don't use batteries with less than 35% power in them. When you see the first drop form 2 lines to 1, change both batteries. This is from experience. One day I found the C-AF to work poorly, it took me some time to find out what was causing this, it was the batteries. I was able to duplicate this behaviour. So always use fresh charged batteries in the grip.

- Always use Dynamic Area AF (you can select it by pressing AF and rotate the front dial). It uses your selected point, but gets help from adjacent points. Be aware that it does not change the area or point like Nikon. Always keep your subject under the focus point for good results. Works much better than single points. NEVER EVER EVER use 11-points, it does not work at all and the AF is very slow in this mode, even on SAF.

- Set CAF Lock to ON in the menus. Everybody say this should be set to OFF, but it's WRONG. I tested this and CAF Lock ON works much, much better in every single CAF situation I tested, especially for fast moving subjects. From what I saw, the camera is hesitant to change focus by much if this is set to OFF, coupled with the slow 5fps. I repeat, set this to ON before you cry the E-5 cannot C-AF.

I missed a important setting: Set RLS Priority to OFF for CAF.

Also, I think it helps to shoot in full Manual mode and a preset White Balance. The camera doesn't have to process exposure and WB leaving all processing power for AF calculations.

Bumping this with thanks : the subject just came up on another forum and this is a focus behaviour I've never heard of up until now.

Calinature Regular Member • Posts: 463
Re: Clarification on technicalities of fixing Oly CAF issues

Thank you very much for the tips for CAF. It has been hit or miss for me, so I will definitely follow your recommendations. Jeff

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