Weird Back Focusing issue.

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blutch
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p.1 #1 · Weird Back Focusing issue.

I have a relatively new 70-200 VRII that I bought with a D600 and also have used extensively with a D7000.

When I am fairly close to my object at focal length 200 the photos are incredibly sharp. When I am far away using the same bodies and the same lens I have a horrible back focusing issue.

I regularly shoot professional orchestras, bands and Choirs from a balcony or way in the back. I have uploaded a typical photo and a crop of the same photo. I am focused on the woman standing up in the middle with red glasses singing a solo. The focus on her is very soft but if you go a row or two behind her it is very sharp.

This photos is on the D600 1/200th at f/2.8 and 2500 ISO.

I have tried fine tuning, but it doesn't seem to make much or any difference no matter how much correction I employ. Plus it is like this WITH BOTH BODIES. it is almost identical. I have tried all sorts of fine tuning settings from -15 to +15 and none of them seem to correct this problem. Ideas please? Here are the photos:

121211-0070-32.jpg by blutcherama, on Flickr

121211-0070-32-2.jpg by blutcherama, on Flickr

Dec 15, 2012 at 09:33 PM

blutch
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p.1 #2 · Weird Back Focusing issue.

I should also say that I am using AF-S. Not much movement on concert stages like this. Sure would like to get some responses on this. thanks!

B

Dec 15, 2012 at 11:51 PM

sworth
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p.1 #3 · Weird Back Focusing issue.

That looks mighty close to me. Are you sure you weren't locked onto the guy with the sideburns behind her?

Dec 16, 2012 at 04:18 AM

blutch
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p.1 #4 · Weird Back Focusing issue.

Positive. I tried this sort of shot over and over with both bodies. Check out the bald guy two rows behind her. He is tack sharp. B

Dec 16, 2012 at 05:02 AM

Mark_L
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p.1 #5 · Weird Back Focusing issue.

I'd do some more controlled testing in good light at 50x the focal length. Every time I have had a lens consistently miss at long distance the fine tune value has been off. Also check your focus point indicators in the vf are accurate positionally, if they are slightly off you can lock onto something other that what you intended.

Both my D700 and now D800 have issues when the thing I'm focusing on is about the size of the focus point box for example at f/1.4 with someone's eye larger than the af point it will usually nail it but if the eye is the same size or smaller it will miss more often. That may have happened here.

Edited on Dec 16, 2012 at 09:51 PM · View previous versions

Dec 16, 2012 at 02:15 PM

workerdrone
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p.1 #6 · Weird Back Focusing issue.

"I have tried fine tuning, but it doesn't seem to make much or any difference no matter how much correction I employ." (-15 to +15)

If you're doing that under controlled conditions, something is very wrong. Either methods or equipment. 1 or 2 clicks can be very difficult to see the difference depending on FL and aperture, but 30 clicks? Could you provide detailed description of your testing / tuning method?

Dec 16, 2012 at 02:26 PM

MalbikEndar
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p.1 #7 · Weird Back Focusing issue.

I agree that it looks like the camera has focused one row back.

It has been remarked that the focus sensors are bigger than the boxes in the viewfinder. I have also read some claims that the focus sensors can end up slightly misplaced as manufactured. Your scene has a lot of contrasting edges, closely spaced, and at different distances. I would test with a flat target in similar conditions.

Dec 16, 2012 at 08:18 PM

Lance B
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p.1 #8 · Weird Back Focusing issue.

The bloke to the left of the woman standing looks reasonably sharp in comparison to her and she looks to be on the same focus plane. Seems strange.

Dec 16, 2012 at 11:35 PM

mshi
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p.1 #9 · Weird Back Focusing issue.

It's a known issue with the lens. All you need to do is to send it in so that Nikkon can realign the lens elements.

Dec 17, 2012 at 01:03 AM

blutch
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p.1 #10 · Weird Back Focusing issue.

I have not tested it in a controlled environment.. just on the gig. This is the third concert I have shot from a long distance with this issue. Again.. both camera bodies. I have never returned anything to Nikon. Can someone advise me on how to proceed? Will I have to send my cameras as well?

Mark, how can I tell if the focus points in the VF are off?

Thanks everyone.
B

Dec 17, 2012 at 04:15 AM

Ivo Heshusius
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p.1 #11 · Weird Back Focusing issue.

ehh.... 200 mm at aperture 2.8 gives a thin DOF. Did you ever try a smaller aperture value (4/5.6)??

Dec 17, 2012 at 10:06 AM

Paul.K
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p.1 #12 · Weird Back Focusing issue.

Ivo Heshusius wrote:
ehh.... 200 mm at aperture 2.8 gives a thin DOF. Did you ever try a smaller aperture value (4/5.6)??

Uh...you don't buy a $2000 pro f/2.8 lens to shoot f/5.6. Also, at that distance, the DOF isn't that small.

Dec 17, 2012 at 10:15 AM

Mark_L
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p.1 #13 · Weird Back Focusing issue.

blutch wrote:
Mark, how can I tell if the focus points in the VF are off?

Not sure what the best test is really beyond sticking the camera in af-c and moving the camera slowly off something close you have focued on and seeing when the focus moves to the background. Then repeating this for up, down, left, right.

Dec 17, 2012 at 12:53 PM

pbraymond
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p.1 #14 · Weird Back Focusing issue.

I've had issues with the Nikon bodies focusing differently under different lighting sources. Try this - do an AF test in daylight, then try the same object under tungsten lighting - I've seen different results, and it's different with different lenses.

May or may not be the problem here, but something to try out for free.

Dec 17, 2012 at 01:23 PM

blutch
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p.1 #15 · Weird Back Focusing issue.

Pbraymond,

It is difficult to recreate this scenario in daylight, but I did test it a bit yesterday on a bright day and it didn't seem to back focus. I need to find something "stepped" to shoot that is sort of like that choir, but it doesn't seem to have the problem in real light. B

Dec 17, 2012 at 02:28 PM

James R
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p.1 #16 · Weird Back Focusing issue.

Paul.K wrote:
Ivo Heshusius wrote:
ehh.... 200 mm at aperture 2.8 gives a thin DOF. Did you ever try a smaller aperture value (4/5.6)??

Uh...you don't buy a $2000 pro f/2.8 lens to shoot f/5.6. Also, at that distance, the DOF isn't that small.

Uh, you're not saying that a "pro" lens should always be shot wide open? The 70-200 G VRII is a better lens shot at 4 or 5.6 than 2.8.

Dec 17, 2012 at 03:14 PM

blutch
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p.1 #17 · Weird Back Focusing issue.

Because of the type of shooting I do - low light, long distances - I often need to shoot at 2.8. If I can get away with 4.5-5.6 I will use it. That said, I have tested this stopped down a bit and the problem still exists.

I have an older AF 300mm F4 and after fine tuning, I have gotten good results using a monopod with this lens under the same scenario. I REALLY do not want to be chained to a monopod. It is cumbersome and a bit noisy and limits the shots I can get hand held. I bought low light bodies and the 2.8 VRII lens to be able to shoot hand held in this situation.

B

Dec 17, 2012 at 03:23 PM

James R
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p.1 #18 · Weird Back Focusing issue.

"I REALLY do not want to be chained to a monopod."

I always try to shoot the 70-200 at 1/300th sec. for best results, and use the back-button focus. In a dark setting, a monopod can make a big difference and getting the shot is what's important. How does the D600 handle ISO 3200 or 6400?

Dec 17, 2012 at 04:09 PM

pbraymond
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p.1 #19 · Weird Back Focusing issue.

blutch wrote:
Pbraymond,

It is difficult to recreate this scenario in daylight, but I did test it a bit yesterday on a bright day and it didn't seem to back focus. I need to find something "stepped" to shoot that is sort of like that choir, but it doesn't seem to have the problem in real light. B

I've demonstrated the effect to myself with simply a paper target by the window, tripod mounted camera w/remote release. Shoot with daylight, close the blinds and shoot under tungsten lighting, and the focus is shifted. Fairly repeatable probably 70-80% of the time the fcous changes, but not 100%. Drives me crazy, but I calibrate my lenses to daylight and try not to shoot in tungsten lighting, or at least try to make adjustments if I do shoot in tungsten lighting. What's even worse is with some zooms, the degree of focus shift also seems to change with focal length. I think with the really high res cameras today it's more easily observable; not quite sure if it's technology that's gone bad.

Another possibility is that the focusing area is larger than the face you are focusing on, and it's capturing the bearded man the lady behind it since that has more contrast. In that particular pciture, I probably would have checked focus in playback, and maybe aimed the focus target at the hand surrounded by the black music book.

Ray

Dec 17, 2012 at 04:30 PM

cltmte
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p.1 #20 · Weird Back Focusing issue.

My monitor may be off a bit but it looks like the three people to her right (our left) are quite sharp and even the gentleman obscured by the conductor is slightly sharper. Maybe "subject" movement?? Just a quick thought.

Mark

Dec 17, 2012 at 04:38 PM

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