Focus bracketing vs CAF?

[hazwing]

I've got a 8 month baby, who's sitting up by herself now. She's a bit wobbly and can move around a little bit. It can be hard getting a perfectly focused shot when she moves around.

I've been mainly using a GM5 lately, and AFF with eye detection generally gives me okay results. However sometimes the AFF itself hunts slighty, or bubby moves a little and I sometimes get a shot that is not critically in focus.

I'm just wondering whether it might be worthwhile trying the focus bracketing system in the newer OMD cameras. That way when the focus racks from front to back, there's a fair chance one of the shots will be in perfect focus?

Anyone tried this? What focus differential are you using?
I will play around with this with my new em10 mk2. Focus differential of 1. Sequence of 5. Will try lock focus on target and then move my head/camera back a little, to capture the area in front of the initial focus lock.

 

[Growltiger]

What a clever idea. It should work.

 

[jyc860923]

I have the idea the moment I read my GX85 manual, as I want to shoot my dog run and that wasn't an easy job with my previous G6. But, I gave up using the focus bracketing (GX85 has this feature too so not just the OMD series) because it takes a burst of shots both front and back focused and that's not efficient for dog run. That said, you might find this function a bit more useful if your daughter's moving slightly out of focus, unlike the dog runs straight towards me. What I suggest you try despite what others may have said, mostly negative about, is the AFC+tracking mode. The tracking I've found a lot more usable on my GX85 even for dog run and so I think the tracking on GM5 could at least handle some back and forth movements within a limited range, though I've never tried the GM series.

There are a few things to notice:

1. Panasonic has been known for acquiring focus crazy fast, however, in tracking mode, it isn't always easy to lock onto your subject perhaps because it needs certain amount of, well, something to recognise the thing to lock onto; but once it does, let's say a face in near distance not moving very fast, paired with a fast AF lens in good light, it should be quite manageable to get good shots.

2. Also, pay attention to the AF modes, somehow there's AFS tracking mode on my GX85 IIRC and that does things a little differently than AFC tracking, you probably want to try first then decide.

3. Aperture lag. This is something I get from shooting dog run, lenses like PL25 1.4 and P42.5 1.7 or just many non-pro/older lenses can cause extra lag if stopped down, you can tell by the rattle sound they make. I think newer camera bodies may make more predictive AF throw to compensate this. Another thing that may or may not be an issue when shooting actions is the 1/50s fastest global shutter speed provided with the GM series, but I haven't used it, does anyone know?

 

[Drdul]

I just acquired a camera with focus bracketing, and I've been testing different settings to see how it could work for street photography. Similar enough to the OP's situation with a baby moving around. In my case, I've settled on 5 images at the narrowest focus differential of 1, with focus set manually at approximately 1.0–1.25 m for the starting image. The key is that the focus has to be set at the closest point, as the camera adjusts focus at further distances in subsequent images. In my case, that gives me 5 images in focus from approx. 1.0 m to 5.0 m.

The focus differential is apparently proportional to the initial focus distance. So if I had focused at 0.5 m for the starting image, the focus point for the final image would have been much less than the 5.0 m I got by starting out at 1.0–1.25 m. So if you want to photograph your baby from a closer distance, a focus differential of 1 would still likely work. In any event, it's easy enough to test. I set up a series of targets (boxes and bottles with clear print on them) at 1.0 m intervals so that I could see how the focus point moved from image to image.

The one thing to note is that focus bracketed images are shot in silent mode with the electronic shutter (presumably to avoid shutter shock when taking macro photos). So if a baby (or a person on the street) is moving quickly across the frame, some rolling shutter distortion might result. I haven't tried it IRL yet, and will report back if I encounter any showstoppers.

 

[Klorenzo]

It's not a bad idea but I wonder if it works in practice. If she wobbles back and forth there is no guarantee that she will do this in synch with the focus shift. In the worst case scenario the focus shift can make things worst. Instead if she is static and the focus was a little off this makes sense.

I would also try a simple "high speed" burst mode (maybe with a slow fps speed) with focus on the first frame only: if she wobbles she should eventually pass in the DoF zone. If the focus was too close and she moves closer you are lucky, it's a 50% thing. If the burst is very long you will catch the next oscillation but it may take a while, that's why I say to use a slow fps value.

And also try a "slow speed" burst with "eye detect" enabled so that the camera refocus on each frame: the idea here is that your reaction time is bigger than the camera, while in slow burst mode the camera releases the shutter as soon as it gets focus. A similar option is to press the shutter fully rather than in two steps with simple AF-S.

I never tried this, but I know the problem, I think you just have to see what works best.

 

[wjiang]

I was getting the most keepers with face detect, S-AF, Seq-L on the E-M1 when baby was less mobile. That would generally get some in focus after the initial acquisition.

Now a crawler, that doesn't work nearly as well unless she isn't moving around. I get the most keepers by predicting her movement. If she's really on the move close to me, however, I find it rather difficult to keep up. C-AF doesn't help all that much...

 

[hazwing]

I tried the focus bracketing... doesn't work that well in practice for the purposes I am consider.

AFF on panasonic is resonable but still get a number of out of focus, or just slightly out of focus images. CAF + tracking on em10ii similar results.

Now just trying back to SAF + pump the shutter button. (make sure the review photo mode is turn off)

And as you say... now with little one moving around a bit more, I'm feeling more let down by the poor CAF of m43.

I wouldn't mind the aperture bracketing on some of the new panasonics. The other thing I'm finding is when holding baby, she sometimes moves back and forwards while holding her. For these two people portraits, I want the thinnest DOF but enough that both people are in focus. Aperture bracking opens some interesting possibilities.

 

[tino84]

I don't think it would be the right tool for the job. On the Panasonic gx85 focus bracket requires to be steady.
Instead, Panasonic 4k video mode allows to capture a video and than select the frame you want, that's the way I select to shoot my sister's little kids when playing (instead of trying to not loose focus with single shot and af-c)

 

[Deleted member 20897]

Learning to use off camera flash can be a great thing. My guess is that shooting indoors, keeping your shutter speeds too low. You can keep a speedlight or 2 up and ready, turn them on and start firing away.

 

[wjiang]

For two people portraits you really should stop down some (f/2.8 is the widest I'd feel comfortable with), and move to align both subjects to the same plane of focus. Bounce flash helps a lot with this indoors.

 

[wjiang]

Learning to use off camera flash can be a great thing. My guess is that shooting indoors, keeping your shutter speeds too low. You can keep a speedlight or 2 up and ready, turn them on and start firing away.

That's a good point. Indoors I'm generally shooting shutter priority with the baby - I find I need at least 1/200s otherwise she inevitably has motion blur.

 

[Deleted member 20897]

That's a good point. Indoors I'm generally shooting shutter priority with the baby - I find I need at least 1/200s otherwise she inevitably has motion blur.

Honestly, I don't do it often, but sometimes for Christmas, sitting around a dimly lit tree or in the winter when you just don't have as much daylight hours to work with. Most don't mind and get used to it rather quickly.

 

[pake]

And as you say... now with little one moving around a bit more, I'm feeling more let down by the poor CAF of m43.

My first week with the GX800 hasn't improved my feelings on this matter either. I was hoping it would be able keep up with our dog but the miss ratio is still way too high. I've tried all modes and settings but none of them gives results I hoped for. And even the AFC while shooting video is still pretty much unusable.

 

[hazwing]

My first week with the GX800 hasn't improved my feelings on this matter either. I was hoping it would be able keep up with our dog but the miss ratio is still way too high. I've tried all modes and settings but none of them gives results I hoped for. And even the AFC while shooting video is still pretty much unusable.

I thought the gx800 with DFD would have a bit better CAF?

 

[pake]

I thought the gx800 with DFD would have a bit better CAF?

So did I but so far I haven't been able to achieve it. But I've only tested CAF with the new(ish) 25mm f/1.7 and I'm hoping my wife's 12-35mm and 35-100mm f/2.8 lenses will do better...

 

[Klorenzo]

I thought the gx800 with DFD would have a bit better CAF?

I think DFD improves the focus speed mostly when big focus distance changes are involved. The final part is still handled with small back and forth steps like in normal CDAF (I suppose the "defocus distance" is not accurate enough). C-AF, for slow moving targets, probably works just in this final "fine tuning" zone so it should not make much difference.

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