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BL3
01-31-2008, 01:18 PM
I've been having dismal results trying to get CAF to work on my E-3, on at least one occasion I had a hit rate of zero--nothing was in focus. With my E-1, I could at least get around 25 to 30 per cent hits. So, in the shower today (all my revelations seem to come while showering--maybe I should do it more often) I had the thought "Maybe the AF can't keep up with the sensor if it's jumping all around while trying to accomodate my shaky hands!" I remember a line in the manual about turning the IS off at high shutter speeds, and another thread in the Focus malady posts by no less than EB himself where he felt that focus problems were somehow related to IS settings. Without actually shouting "Eureka!" I went outside and set my E-3 to Shutter Priority Mode, 1/400 seconds, Auto ISO, IS-OFF, and the "diamond" focus area selected, the lens was a 150/f2. Shazam! Pretty near all shots of cavorting Border Collies were in focus. I'll not belabor you here with more pics of my dogs as I have made a resolution to try and spare the poor members here, but trust me, these shots were in focus. I'm thinking that at least with the longer lenses, the IS has to move the sensor around to the point that the AF function is at least impaired. If I'm right, the point may be that sound photographic principles must be upheld, in spite of tech advances like image stablilization. Please be mindful that I still have a lot more research to do before I can state unequivocally that I've found the solution, but I think I'm on the right track and I hope that others here will chip in as well.

Rocky

E B
01-31-2008, 02:47 PM
Or, it could be that IS has nothing to do with the problem. Maybe previously the shutter speed was too low and you were seeing subject movement, not a focusing issue? IS helps control the results of camera shake but can't do anything about moving subjects and, since you were using C-AF I assume the subject is moving. To capture moving subjects you still have to use a higher shutter speed. Ideally, you should be using C-AF plus a high shutter speed and IS=2 if you are panning.

BL3
01-31-2008, 03:29 PM
Yeah, I'll try using the IS while in Shutter Priority mode as well. I wonder if this presumed interaction between IS and CAF is the reason the camera defaults to Release Priority C-ON. Could it be that allowing an exposure when focus hasn't been achieved is a way to give the autofocus function some slack, since the ("shaky") sensor may be inhibiting its ability to come up with a solution?

The day that I had the 100% failure rate using CAF, I was using the P mode, but I was careful to select a shutter speed of 1/200, which should have been fine with the 150 lens given that I was using image stabilization. It was a fairly bright day, and I was trying to track a helicopter traversing an otherwise unobstructed blue sky at around 40 knots of airspeed. It should have been easy for CAF, but I was unable to attain any pictures in focus, until I shifted to SAF, where my keeper rate went above 90%.

I obviously have a lot more testing to conduct. I have to remind myself that this camera is much more complex than its predecessor, and its higher resolution can sometimes resolve mistakes that the E-1 would have overlooked.

Rocky

E B
01-31-2008, 04:08 PM
Release Priority C=On allows the camera to trip the shutter at its fastest cyclical speed (5 fps). Release Priority C=Off will slow the camera to about 3 fps or slightly less, but the focus should be good.

A shutter speed of 1/200 should have been ok with a stationary target since you had IS=On. Much too slow for a moving target. 1/500-1/1000 would have been better. Running dogs need about 1/1000. I can do birds in flight at 1/1000 if they aren't too close. A helicopter doing 40 knots is fast.

BL3
01-31-2008, 08:57 PM
I knew I wasn't getting 5 fps. from my camera, and now I know why, so thanks are in order. As for shutter speeds, my professional aviation photographer friend is always busting my chops for having too high a shutter speed, as it freezes the rotors on helos instead of getting that nice blur. It could well be that I was overcompensating at 1/200 th. shutter setting, but I have gotten usable shots from my E-1 at 1/250, with a slightly longer lens (200mm vs. 150). I'm pretty sure I'll get the CAF to work for me, maybe along with image stabilization. I had yet another thought, this time not in the shower, that maybe part of my problem may lie with my use of standard vs. SWD lenses. Maybe the lenses I use can't keep up with the focus instructions from the camera. I sometimes get that feeling as I look through the viewfinder and see the image surge into and out of focus, even on a stationary target. I hadn't planned on buying any of the new lenses, but I'll admit the 14-35 is beckoning. Last week, I sort of got the 11 point focus area to acquit itself for me, this week I'm finding a way for the CAF to work. My feeling is that since I'm going to be more circumspect in the selection of shutter speeds, I won't really need image stabilization in the first place if the shutters speeds are high enough. Moreover, I need to experiment with mode 2 of image stabilization, perhaps with my GV2 gimbal ballhead. Thanks again for the tips.

Rocky



Rocky

windsprite
01-31-2008, 09:12 PM
1/200" is definitely too slow if the subject is moving toward you, but it seems like it should be okay if you're panning an aircraft (for dogs, it's right on the edge of being too slow--the head, which bobs up and down, gets blurred).

For panning, I'd normally use S-AF instead of C-AF and feather the shutter, but you should be able to get results from either. A little experimentation should tell you which gives you more keepers.

BL3
02-05-2008, 02:49 PM
Hope I'm not drawing this old thread out too far, I've been fooling with Tony's recommendation to use Mode 4 for CAF, which moves the initial autofocus function from the the shutter button (half press) to the AEL-AFL button. I'm not sure why or how this can help, so far it at least seems to work on what I can find--passing trucks, high-flying aircraft etc. Nothing definitive yet, however.

Rocky

BL3
02-06-2008, 09:35 AM
I'm pretty satisfied that I have tried every variation of settings to get CAF to work reliably for me, and I think I've found the answer. It came to me while playing with a friend's new D3--we were getting a sporadic hit rate when using the Nikon version of CAF. My friend, a professional photographer, said that he hadn't yet mastered the (51 point!) autofocus system, but with his previous camera, a D2X, he just shot everything in the Nikon version of SAF. Today, I spent a few hours experimenting with every thing mentioned here, and I came to realize Julie's advice to shoot panning shots with SAF was probably the most useful for me. Regardless of what focus field, or normal/fine focus point, shutter speed, IS setting, focus lock on/off, AEL mode, etc. that I use, I can see the CAF setting causes whatever lens I have on the camera to "surge" into and out of focus, even on targets that are not moving. At best, on stationary targets, the hit rate is below 50%, and even lower on moving targets. Conversely, I get over 90% hits on moving targets using SAF. It may well be that I had unreasonable expectations regarding continuous focus, that was mirrored by my experience with the D3. Maybe a 20 to 30 percent hit rate is acceptable given the limitations of the equipment? I admit that my inability to get CAF to function reliably may be the result of poor photographic techniqe by me, but I won't worry about it because I get good results from SAF. Hopefully, someone will come up with a workable solution, but until then, I can get by with SAF. That D3 is indeed an amazing camera, by the way.

Rocky

heavy wind lover
02-06-2008, 10:20 AM
on the grandkids basketball games I am back to SAF as the CAF offered a lower rate of keepers,, have tried with the 12-60 SWD and the 50-200 non SWD and it made no diff,, feathering the release while following the subject just worked better for me,,

Derry

llpoolej
02-06-2008, 10:28 AM
CAF rocks with my camera, especially paired with the 50-200 swd. I don't like it to be set to a bunch of focus points, the single small works the best. It was working well before the firmware update and after.

Here is a gallery from a whippet board I am on. http://groups.msn.com/WonderfulWorldofWhippets/general.msnw?action=get_message&mview=0&ID_Message=52615&LastModified=4675659506766411333
and the completed set http://www.llpoolej.smugmug.com/gallery/4287953

Also here is photos done in crappy light of basketball http://www.llpoolej.smugmug.com/gallery/4268679

If you can't get it to work, I would send the camera in. As the CAF is actually excellent. Though, if you are using it to photo fast moving objects at 1/200th, you will see motion blur

E B
02-06-2008, 10:39 AM
I came to realize Julie's advice to shoot panning shots with SAF was probably the most useful for me. Regardless of what focus field, or normal/fine focus point, shutter speed, IS setting, focus lock on/off, AEL mode, etc. that I use, I can see the CAF setting causes whatever lens I have on the camera to "surge" into and out of focus, even on targets that are not moving. At best, on stationary targets, the hit rate is below 50%, and even lower on moving targets.
Rocky

C-AF on Olympus cameras uses predictive auto focus. That means that the camera is anticipating a moving subject and changes it's focus point in anticipation of the movement, with the direction and amount of change based on previous auto focus measurements. The result of that is that C-AF doesn't work well with stationary targets since the AF will jump off of the subject in antipation of the subject's movement.

You should get a pretty good keeper rate if using C-AF on the E-3 and a SWD lens with a target moving along a low deviation trajectory (e.g. race cars) even though the speeds are extremely high. Keeper rate should fall as the trajectory deviation increases (e.g. barn swallow in flight or soccer ball in play.)

If you're not using a SWD lens, your lens probably can't keep up with focusing changes required by the camera body and your best alternative may be S-AF.

BL3
02-06-2008, 02:17 PM
Thanks again to everyone who helped here, especially for your patience while I stumbled through various schemes and plots to get to where I am now. This next shot, taken with an E-3 coupled to a 150/f2 + TC20, in SAF, 1/500 @ f5.6 as the helo was running down the runway at around 60 knots, just after takeoff:

http://bl3.smugmug.com/photos/251653051-M.jpg


Rocky

PS: Monopod, IS mode 2

dh202
02-06-2008, 04:27 PM
Thats a great shot Rocky. You even caught the heat waves coming off the engine!
David

BL3
02-06-2008, 10:47 PM
Thanks, David. I thinks that's what a heat seeking missile looks for.

Rocky

Don Baldwinson
02-13-2008, 11:10 PM
Thanks again to everyone who helped here, especially for your patience while I stumbled through various schemes and plots to get to where I am now. This next shot, taken with an E-3 coupled to a 150/f2 + TC20, in SAF, 1/500 @ f5.6 as the helo was running down the runway at around 60 knots, just after takeoff:


Rocky

PS: Monopod, IS mode 2

Hi Rocky, I only just discovered this thread, and in view of my trials and tribulations using C-AF, I will try S-AF this weekend. The jury is still out I feel, because of the permutations available on the E-3, and the difficulty in doing meaningful side by side comparisons using erratic fast subjects.
A great helicopter shot of yours, and the best really sharp image I have seen using the EC-20.
Cheers,
Don

BL3
02-14-2008, 07:04 AM
Thanks for the photo note, Don. I have come to think that the way to get CAF to work is to know when it is needed and will work, as opposed to using it for anything that moves. As Julie noted, CAF is not needed for panning shots if you can keep the target (relatively) stationary in the viewfinder. CAF is needed when you can't track the subject, or its constantly changing its position in relation to the photographer. It'd be interesting to hear Ray's take on CAF after shooting some more football games with it.

Rocky

SimonWallwork
12-05-2008, 03:23 PM
English Bob

Just for clarity

You're saying that when the 'C' is displayed on the camera top, it'll fire when OOF?

Remove the 'C' and you're back to 3 fps but E-3 only fires when in focus.

Instructions impossible (for me) to decipher!

bitslizer
12-05-2008, 03:48 PM
AF sensor reside on the bottom of the mirror box, nothing to do with the IS which is physically mated to the imager sensor in the back of the mirror box

Body base IS should not affect AF, however lens base IS MAY help AF

Now have to differenate between motion blurred subject vs out of focus subject.

CAF would assume you are moving the camera to track the subject, in that sense the IS maybe fighting your panning and create motion blurred subject
which is different that OOF subject


I think the moving to the Diamond AF is what did the trick, you can also try going to single point AF


Not sure where I read it, A Oly Rep stated that CAF work best when the background is featureless, like a flight of birds in a clear sky.

A dog running around with the lawn/trees in the background make it harder for the CAF to find what to focus on,

by the same token using all 11 AF point with CAF is just asking for trouble as the camera have no idea which AF point to use, that's why I thought the diamond/5 point AF is what improve your CAF result and I think moving to single spot AF will help even more, of course that is assuming you can keep that single AF spot on a moving subject

---- Edit

Holy... just notice this was a Necro thread :p

moggi1964
12-05-2008, 04:50 PM
Thanks, David. I thinks that's what a heat seeking missile looks for.

Rocky

Next time I am flying a helicopter and someone fires a heat seeking missile at me I will know to turn off the engine. The satisfaction I will get from dying in the impact of hitting the ground from a rapid loss of altitude rather than the bad guy hitting me with his missile will be priceless.:D

Actually, I am learning tons from this post; being new here it is great to see an old thread resurrected with such informative content.

Thanks.

NickG
12-05-2008, 11:39 PM
Actually, I am learning tons from this post; being new here it is great to see an old thread resurrected with such informative content.

Thanks.

Agreed. Me too! :)

photo_owl
12-06-2008, 04:20 AM
"Next time I am flying a helicopter and someone fires a heat seeking missile at me I will know to turn off the engine. The satisfaction I will get from dying in the impact of hitting the ground from a rapid loss of altitude rather than the bad guy hitting me with his missile will be priceless."

well actually there is no reason for it to all happen like that at all - I guess you haven't done a lot of rotor flying?

on the other hand I know suspect that this wouldn't be the behavious of anyone on here - if they saw such a missile fired at them they would all get their E3's out for one last test of the C-AF function!

moggi1964
12-06-2008, 06:33 AM
........
on the other hand I know suspect that this wouldn't be the behavious of anyone on here - if they saw such a missile fired at them they would all get their E3's out for one last test of the C-AF function!

See; I still have so much to learn ;) :D

BL3
12-06-2008, 10:59 AM
Just for argument's sake, one procedure to counter an IR missile threat is to simultaneously reduce power, or even enter autorotation, while executing a sharp turn to both reduce IR signature and possibly mask it, and employ countermeasures such as active jamming and flares. Once the missile has broken lock and is no longer a threat, then you can break out your E-camera and document your supberb airmanship or the nice vapor trail.

So, Moggi1964's instincts were good, except for the crashing part. How did this get so far O/T?!

Rocky