Nikon D4 Af-S FPS

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tiddlybiz

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Chris
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Hello, I got a Nikon D4 a while ago and it has been a mixed bag of amazing and broken but one thing that I can't seem to figure out is the continuous release FPS in AF-S focus mode. It seems to slow right down to a few FPS unless pointed at a bright light and it isn't the shutter speed limiting this. In AF-C mode all is fine and it tracks at full speed without issue. Since the focus should be locked in AF-S I don't really understand it. Has anybody else experienced this?

My D3 on the other hand appears to have the opposite problem which is more understandable. i.e. it will shoot at 9fps locked in AF-S but struggles a bit in AF-C.
 
Release and focus for AF-C and focus for AF-S. But AF-S should be locked once in focus as far as I'm aware and should fire once in focus.
 
Expect approx. 10-fps shutter bursts with full AF and AE performance in FX format. The frame rate can also be boosted to up to approx. 11 fps*1,2 in FX format. The camera's large buffer memory allows shooting up to approx. 100 frames*3 in RAW and up to 200 frames*4 in JPEG (when using SONY XQD Memory Card H series QD-H32 with 32 GB capacity). This enables photographers to maintain high-speed continuous shooting without worrying about buffer memory capacity – a real advantage that cannot be measured by fps rates alone.
  • *1The frame rate assumes continuous-servo AF, manual or shutter-priority auto exposure, a shutter speed of 1/250 s or faster, and other settings at default values. Frame rate may drop at extremely small apertures (high f-numbers) or slow shutter speeds, when vibration reduction (available with VR lenses) or auto ISO sensitivity control is on, or when the battery is low.
  • *2In continuous high-speed mode at 11 fps, some of the second and subsequent shots in each burst may not be in focus and exposure may not accurately track poorly lit subjects.
  • *398 frames on average, image quality: 12-bit compressed RAW, under test conditions established by Nikon.
  • *4Image quality: JPEG (fine/Medium)
Click to expand...
 
Interesting, It does suggest using AF-C. Sure why that would be the case but looks like it is!
 
AF-S and CH seems like an odd combination to me... I'm pretty sure I've done it, but not enough frames to notice a reduction in speed. I could test mine if it matters....
 
It isn't something I use much but does occasionally have a use such as taking photos of groups in a room and firing off a burst to ensure nobody blinks or something. I still generally use AF-C for that but is a possible situation it could be used. If you don't mind having a quick check that'd be helpful! The slow down is pretty obvious on mine and doesn't require any detailed analysis.
 
A quick test using your settings:
With AF activation on the shutter release, no reduction in FPS.
With AF activation on the AF-on button only, a significant reduction in FPS. This is due to the current firmware having re-enabled "trap focus" when using BBF and AF-S (the shutter doesn't release unless the image *is* in focus).
 
Interesting, thanks a lot for looking into that. I do use BBF and hadn't considered that it would be due to that. Good to know and I think I'll keep settings how they are as I'd rather have it in focus in AF-S than be able to fire off a million shots!
 
And "trap focus" is a pretty neat/useful trick... I guess enough photographers complained about Nikon "breaking" it that they re-enabled the behavior. But it requires more specific settings with the newer cameras than it used to. According to the firmware notes:
  • When AF-ON only was selected for Custom Setting a4 (AF activation) and the AF-ON button was pressed to initiate autofocus during viewfinder photography, focus remained locked even after the user took their finger off the button, and the shutter could be released at any time. However, specifications have been modified so that the shutter cannot be released under the following conditions if the camera fails to (find)** focus.
    • Autofocus mode is set to AF-S (single-servo AF)
    • AF-area mode is set to Single-point AF
    • Custom Setting a2 (AF-S priority selection) is set to Focus
* - We have prepared a supplementary user's manual that covers this function. Click here to download the supplementary user's manual. Adobe's Acrobat Reader must be installed on your computer to view this file.

** "(find)" added by me...
 
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Thanks for that info. Trap focus is not something I've found much use for myself as the af system is generally quick enough to pick up and track things. It would be nice to have to have the option to turn it on and off when required.
 
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