Slightly Blurry subject even with flash

[swipepics]

Hi All,

Am new to the forum so this is my first question.
I have a reasonable understanding of how to avoid camera shake but am facing an issue that i dont understand fully.

Am using a 70-200 f2.8 vr1 nikon lens on a DX body (d7000). With vr on shooting all focal lenghts but especially so on the higher end i'm experiencing slight blur on the subject. Nkticable in the eyes. These are 2/3rds to full length portraits at 120-200mm. I even tested in bright sun with iso 100 to eliminate noise related blur but still keeping sjutter speed high (at least 1/320s bearing in mind crop factor and shooting like there is no vr). My hands arent perfect but they are quite steady.

what confuses me most is that this happens even at 1/1000s BUT a couple out of 10 shots are tack sharp!! So dont think the lens focusing is off.. I always focus on the eyes of the subject fyi
I mentioned flash in the subject because i get the same results when i use flash off camera closer to the subject on a decent power setting.

Is this something with the lens? Any ideas please..
Also open to hearing any related tips on technique in using this range of telephoto.

thanks

 

[paigew]

post a photo with settings.

 

[gsgary]

I will have a bet that you are shooting at F2.8

 

[tirediron]

I will have a bet that you are shooting at F2.8

I'll give you even money!

Example image and full EXIF data please.

 

[480sparky38 37]

Manual or AutoFocus?

A link to an unedited, full-size JPEG will provide a quick solution.

 

[swipepics]

Many thanks for the quick responses.. I'll post some samples as soon as can.
in the meantime to answer some of the questions..

i was using auto focus, af-s, and a range of f stops..
I thought the issue was thin dof with 2.8 so i tried larger dofs

thoughts?

Manual or AutoFocus?

A link to an unedited, full-size JPEG will provide a quick solution.

 

[480sparky38 37]

In AF-S, once focus is detected the focusing stops. If you or the subject move between that and shutter actuation, you may end up with the wrong focus point

 

[Derrel]

In AF-S, once focus is detected the focusing stops. If you or the subject move between that and shutter actuation, you may end up with the wrong focus point

That is a good point regarding AF-S, and people work. I have owned the VR-1 for a decade...I've found myself that at FAST shutter speeds in good light, VR can create a very slight softness..and it's for lack of a better word, "weird" in the way it looks.

A second issue might be what is called "ghosting"; this happens when the ambient exposure is close to the "flash exposure" level...there are in reality, two, separate exposures being made, one by the flash, the other by the ambient light exposure. Ghosting is a BIG problem in many bright light + flash situations; it can be used to creative effect with slow speeds and second-curtain shutter synchronization. A second thing: in BRIGHT light, using FP Synch, the flash fires at a very high Hertz, so the flash is actually not ONE, single, discrete "POP!" of flash, but is instead a very closely-spaced sequence of many,many,many micro-flashes, so shooting FP synch flash photos on normally-moving people in bright, beach- or summertime light levels can lead to a weird softness that is often easily seen in the catchlights of the eyes.

Nikon has an article that encourages users to switch the VR to "OFF" unless it is absolutely needed. At speeds above 1/500, VR in the VR-1 70-200 can cause a weird loss of sharpness, and I have seen it myself on many exposures.

 

[raventepes]

My first question is weather or not the OP is shooting on a tripod with VR on...

 

[Dao]

I kind of also think the subject was out of focus. Telephoto with wide aperture = shallower DoF. So the subject could just walk out of the focus plane between 1/2 press full press of the shutter button.

 

[cynicaster]

The OP says the problem occurs at 1/1000 shutter speed, and with flash. With the latter, depending on how much ambient light is in the mix, the motion is being frozen at ~1/8000 sec or so. Hard to imagine camera shake being an issue under these conditions.

Be it due to operator error or equipment malfunction, sounds like a slam-dunk case for missed focus to me.

 

[KmH]

"Telephoto with wide aperture = shallower DoF."

Shallower than what?

If less focal length is used, the camera has to be closer to the point of focus to maintain image scale in the image frame.
Using the same aperture at both focal lengths, and maintaining subject scale in the image frame, the DoF is almost exactly the same at each focal length.

The difference is that the longer focal length magnifies the blurred background more making it seem more blurry when it actually isn't.

Using flash and 1/1000 shutter speed usually requires a high speed flash sync mode and the flash has to fire multiple times during a single exposure.

 

[swipepics]

Hi All,

Thanks for your inputs - they've been very useful in my thought process about the whole thing.
Sorry for my slowness to reply, been away for a bit but I have managed to do some more tests (a few hundred pics!) with positive but still confusing results...

Basically I decided to test the AF by turning it off and manually focusing while keeping the VR on. After a couple of test shots to get the eye of my subject in focus I let go of the focus ring and took shots freely. I even allowed my self to be sloppy with technique by dropping the camera to my hip and raising it quickly then shooting without giving myself much time to stabilise. The results - I was consistently able to get sharp images at 200mm f2.8 on all pictures even at SS as low as 1/100s, and reasonable amount of sharp ones at 1/60s!

I repeated the test with my old 35-70mm f2.8 lens (where i faced similar issues) again at 70mm f2.8 and SS down to 1/50s with similar consistent results - this lens does not have VR.

So that rules out several things for me and brings the point down to the accuracy of the AF. I'm aware that AF needs sufficient light to be accurate, and to see a good line of contrast for focus, but while the tests above were performed in lower light.. there were many that I performed in bright sun with AF on yielding slightly (but not much) better results and really taking my time to stabilise before I focus and squeeze the shutter steadily.

Could be that I need to AF fine tune as both lenses could be front or back focusing which I will try BUT some of my initial tests did come back tack sharp which confuses that point. :-\

Thoughts?

Thanks