Every second photo blurry?

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Every second photo blurry?

Post by TooTallDean » Tue Jul 30, 2019 12:03 am

I have noticed something odd with my photos recently.
When shooting flying aircraft with camera on continuous motor drive, my photos alternate between sharp and soft.
I think I am panning along fine, so I dont think I am pausing between shots.
Also, it just looks soft, not smeared.

Nikon D7000
Sigma 150-600mm Contemporary

Usually f5.6 at 1/1000, and ISO 200, or thereabouts.
Drive on CL ( Continuous Low speed)
Lens generally not maxed out, but around ~400-500mm
Pre-focused, and focus range set to 10m-infinity

Any thoughts as to why they alternate?
If they were ALL soft, I would look at the focus.
If they were all smeared sideways, I'd look in the mirror...
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Post by RyanS » Tue Jul 30, 2019 1:23 am

Sounds at first pass like the focus is hunting in and out a bit?

In the case where it loses focus, you can tell the camera to prioritize shooting (it will shoot even if it doesn't finish focusing) or prioritize focusing (it will not shoot until focusing is complete). It may be that it is trying to focus continuously but the frames are coming too rapidly for it to finish in one 'gap' so it shoots anyway, then continues adjusting.

You can maybe try setting it to focus priority or upping the servo speed so it adjusts faster (but is more likely to overshoot).

Conversely, you may try slowing the focus servo speed down so it overshoots less. This may not be able to keep up with fast planes, though.

Not a solid answer but that's all I've got.
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Post by Larry I » Tue Jul 30, 2019 2:45 am

Is the camera set to SERVO (AI Servo) mode? Can't quite remember Nikon's exact name for this. Sound like it may be in single shot.

Edited to add that I think I remember the af servo mode as AFS on Nikon's. You need to use that setting to track moving targets.
Last edited by Larry I on Tue Jul 30, 2019 3:35 pm, edited 1 time in total.
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Post by DanODell » Mon Aug 05, 2019 12:02 am

I shoot a Nikon D500 with a Sigma Sport 150-600mm. I have the Nikon auto-focus set on AF-C and 5 point or D21.

I also have the USB dock for the lens and have tested numerous configs and decided that the following settings work best: OS mode is set to 1. Custom is "Off". Full focus mode.
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Post by Larry I » Mon Aug 05, 2019 2:41 am

Rather than go thru my D7100 manual I looked that up & this is what I found. Certainly worth verifying that the camera in use had been set correctly.

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Post by wfooshee » Mon Aug 26, 2019 4:31 pm

I would use AF-C 3D. That mode actually tracks the point used for the initial focus and makes every reasonable effort to keep it in focus, as long as it's over an available focus point in the viewfinder. You can demonstrate that to yourself by finding some unique feature in the distance. Center it, half-press, and then move the camera around a bit to change that object's location in the viewfinder. The selected focus point at any time will be highlighted, and that selection should remain on or near your initially selected object.
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Post by EricP » Mon Aug 26, 2019 6:14 pm

You don't by any chance have any sort of UV filter attached to the Sigma 150-600 do you? I have UV filters on all my lenses (which are all Canon except for my Sigma 150-600) and the only one I had issues with was the Sigma. I sent my camera/lens to Sigma for calibration and they confirmed that images are softer with the UV filter attached. I am betting the filter may have also caused focus issues, but can't confirm this just yet.
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