autofocus accuracy

[royd63uk]

Hi all

A quick question "does lowering the continuous shutter speed improve autofocus accuracy"
If I use silent shutter at 10 frames instead of 18 or mechanical at 5 or 8 frames instead of 10, will this give the camera more chance to hit focus.

Roy

 

[panamike]

Hi all

A quick question "does lowering the continuous shutter speed improve autofocus accuracy"
If I use silent shutter at 10 frames instead of 18 or mechanical at 5 or 8 frames instead of 10, will this give the camera more chance to hit focus.

Roy

With the small amount of testing i did i found no difference

 

[Toddster]

This doesn't directly answer your question but it may help. With Panasonic there is a setting called "Focus/Release Priority" (separate choice for AFS/AFC). In AFC it basically lets you choose to have the camera shoot at the fps you have chosen or to wait until it acquires focus. In AFS it prevents you from taking a picture before focus lock.

 

[Mack]

Olympus states something about using a lower FPS in the two burst modes that the slower one acquires focus for each shot, and the high speed one does it on first and then is locked for the remainder of the burst.

In my own findings of the low-speed burst, focus does change. I have some animated GIF someplace on here that shows the focus shift from frame-to-frame of a bird sitting on a branch. Focus was locked on bird and shot off a tripod with the small AF spot, but focus does shift a bit between shots in the burst. Only one in three of the sharpest of the 7-frame burst was sharp (i.e. Only 1 in 7 was truly sharp.) as the AF did move/hunt slightly. It easily shows up in FastRawViewer, but it's hard - if not impossible - to see in any other editing software. I can't find that GIF since this new website design doesn't allow me to hunt for my photos uploaded to the gallery here (ahem!).

In my older Nikons, I always took for granted the first AF shot was almost in focus, and the second was closer as the AF didn't need to work to such an extreme to get there. The focus tuning software FoCal seemed to back that up since it shoots multiple shots at the same spot, yet the focus changes and it gets closer as it works the AF of the lens. Sometimes it looks like a shotgun splatter as to where all the AF final points are on their output graph with no two in agreement on the same spot.

Some might be the speed of the lens too. I'm holding off buying the MC-20 2x converter giving that it makes the 300mm an f/8 lens. That's getting pretty dim for me for AF to be reliable unless the subject is bright and contrasty. My Nikons get iffy around f/6.3 and Olympus may get spotty there as well.

I'm disappointed Olympus does not show where the AF square ended up in their Workspace or Viewer 3. Sometimes it is wrong in playback on the camera so it might be something they omit as it does seem flighty at times (e.g. "I see the green AF square here, but it ends up over there." ). There is something recorded about where the AF was in the EXIF in the RAW file, but I wish they would show it in their editing software.

 

[Bristolero]

With the E-M1ii and burst shooting:
Theres been a couple of in-depth posts on focus acquisition by member drj3 over on DPR. His original findings, prior to firmware v.3 is that the first few shots in a burst allow the camera to predict focus for the rest and so shooting the max frames/second will result in the camera locking on sharp focus faster. Interestingly however, he found that after v.3, the camera locks onto sharp focus sooner, often on the first or second frame and hence shooting those first "focus predicting" shots are not as important. Additionally, I recently read from another source, of increased success when turning down the frame rate on shots at incoming birds. My initial testing shows this to be true, and I have reduced my e-shutter-low frame rate to 10 fps. with sharper shots on incoming puffins. Most likely this is more important on incoming stuff, where distances are rapidly changing, rather than birds flying by out in front out in front.
Hope this helps,
Eric

 

[whumber]

Olympus states something about using a lower FPS in the two burst modes that the slower one acquires focus for each shot, and the high speed one does it on first and then is locked for the remainder of the burst.

You're mixing up the Continuous L/H drive modes with changing the framerate within Continuous L. What I've seen overall is that the keeper rate seems better overall when you shoot at higher burst rates; the camera seems to better respond to small changes in speed of the subject and recovers better when it inevitably loses focus. The downside is you end up with a bunch of extra shots most of the time.

 

[Mack]

I found the burst of the sitting bird. No EXIF so I don't know which camera, but I suspect it was the E-M1X with the 420mm (300mm +1.4x TC). You can see the AF changing slightly working down the branch in the burst in FastRawViwer. It was in July, so the camera likely had either the current 3.1 or 1.1 firmware for either the E-1 Mark II or E-M1X respectively. Probably one small focus motor step movement between each frame.

Added later:
The EXIF in the left-most bottom pane shows it was the E-M1X with the 420mm setup that took the burst.

Subscribe to see EXIF info for this image (if available)

 

[royd63uk]

Thanks all.
The reason I asked is, I recently changed from a Canon 7dii (getting older so lighter weight is better) and whilst I am genuinely loving the EMX1 I just wish the autofocus was more accurate for birds in flight which is one of my favourite things.
Dont get me wrong I have some good images BUT I have to delete far more than i did with the Canon.
Perhaps on the next firmware update.