Inconsistent Focus Problem on my D7100

[gohan2091]

oops I meant @Emmanuel

Well I noticed problems when photographing a guy for his album cover (handheld @ 1/160sec). Many shots were soft or lack sharpness. I shot a wedding with the same lens last year at around the same aperture and those photos are so sharp in comparison. What to do when the focus red square is larger than the subjects eye (because im at distance) ?

 

[Horoscope Fish]

oops I meant @Emmanuel

Well I noticed problems when photographing a guy for his album cover (handheld @ 1/160sec). Many shots were soft or lack sharpness. I shot a wedding with the same lens last year at around the same aperture and those photos are so sharp in comparison. What to do when the focus red square is larger than the subjects eye (because im at distance) ?

Well shooting at 1/160 should be good, assuming your focal length was around 100mm or less. Does your lens have some kind of Vibration Reduction or Optical Stabilization? If so, try turning it off; I've found VR can cause as many problems as it solves.

When your focus point is larger than what you're focusing ON, remember that your camera is actually using an *array* of focus points to get a lock on focus (unless you're using Single Point, which I don't really suggest). To see the focus array, look through the viewfinder while pressing and holding down the AF/M button on the camera body (the button right below the button you press to remove the lens). Pressing this button illuminates the focus array in the viewfinder.

This is how things work on a D7100, but I can't recall if we are discussing 7100's or 7000's or both; I assume it works the same on both cameras but if not...

Anyway, on the D7100 you can choose between something like 1, 9, 21 and 51 focus points for the auto focus array. To choose a different number of points in the focus array, press and hold the AF/M button just like before and at the same time turn the sub-command dial (the one on the front of the camera) and look at the LCD. You'll see the different options scroll by as you turn the dial. I use either a 9 or 21-point array but that's just a personal choice. You might try this and see if it helps you get better auto focus results.

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[gohan2091]

I'd like to use only single point focus so I can determine exactly where my camera is focusing. I'd hate the idea of using a cluster of focus points, isn't that what autofocus mode set to Automatic does? Lowering my focus points from 51 to 9 or 21, will just limit the control I have to move about my focus.

 

[Horoscope Fish]

I'd like to use only single point focus so I can determine exactly where my camera is focusing. I'd hate the idea of using a cluster of focus points, isn't that what autofocus mode set to Automatic does? Lowering my focus points from 51 to 9 or 21, will just limit the control I have to move about my focus.

Ummmmm... Not exactly. You need to read this: Nikon D7000 Autofocus Explained

While the title indicates D7000 autofocus the information is applicable to many of Nikon's cameras. It's an excellent read.

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[gohan2091]

I'll have a read thanks. So if you were photographing a person approximately 10-15 feet away using a 105mm @f3 with a shutter speed of 1/160, how would you do it? If you want full and 3/4 shots?

 

[Don Kuykendall_RIP]

I have been shooting all day with my D7100 and 18-140 zoom. I left it on Full 51pt auto focus just to see how it did. If you watch where the boxes light up it was hitting everything just right. Also the focus was spot on when I went to edit them. In the past I have always used spot focus and may go back to it but it was nice to know the 51 pt auto focus is there if I need it.

 

[gohan2091]

hmmm, both of you... you would use auto AFS for portrait shoots? I just tried on some household objects (never heard of this setting before) and it seems to do a good job 9/10 times but would it be suitable for portraits?

 

[Horoscope Fish]

I'll have a read thanks. So if you were photographing a person approximately 10-15 feet away using a 105mm @f3 with a shutter speed of 1/160, how would you do it? If you want full and 3/4 shots?

Ummm... No offense intended but it's really not fair to dictate the settings (105mm @ f/3, 1/160s from 15') and then ask me how I'd do the shoot.

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[gohan2091]

Ummm... No offense intended but it's really not fair to dictate the settings (105mm @ f/3, 1/160s from 15') and then ask me how I'd do the shoot.

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Why is it unfair? I just want to take you to situation I was in last week to compare how you would set the focus to how I do it

 

[Horoscope Fish]

Why is it unfair? I just want to take you to situation I was in last week to compare how you would set the focus to how I do it

Okay, I thought you were asking how I'd shoot the portrait; not simply how I'd focus on the subject.

To answer your question I'd use my standard setting of AF-S, 9 Point and put the focus point on the subject's eye.

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[gohan2091]

Okay, I thought you were asking how I'd shoot the portrait; not simply how I'd focus on the subject.

To answer your question I'd use my standard setting of AF-S, 9 Point and put the focus point on the subject's eye.

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Ok but at that distance, the subject's eye would be smaller than the red focus square so how would you ensure focus is on the eye and not the nose or cheek?

 

[Horoscope Fish]

Ok but at that distance, the subject's eye would be smaller than the red focus square so how would you ensure focus is on the eye and not the nose or cheek?

I put the eye IN the square; that and I use the 9 point focus array.

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[gohan2091]

I put the eye IN the square; that and I use the 9 point focus array.

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On the day, my focus square was too large to fit just the eye, the right edge of the focus square went over the side of the nose and the top of the cheek. It's very easy to have just the eye in the focus square and that's it when you're closer but at a longer distance, I find the focus square too large to fit just the eye.

 

[yauman]

Ok but at that distance, the subject's eye would be smaller than the red focus square so how would you ensure focus is on the eye and not the nose or cheek?

Alright, you are over thinking this At that distance when your little focus square covers the whole face, it doesn't matter if you are focusing on the eye, the nose, the ears or the neck!!! Think of depth of field (DOF) as a percentage of the distance from the subject.
If you are shooting a face 5 feet away, and the head is a foot deep, focusing on the eye (with a big aperture) will put the ears and maybe even nose out of focus. See the depth of the head is 1/5th (20%) of your distance to the subject. Now, move the subject to 50 feet away - your focus square will cover the face but the depth of the head is only 1/50th (2%) of your distance - so it doesn't matter if you are focusing on the nose or the ears; everything on the face is considered the in the same plane - the fact that the focus square remains the same size is telling you that the camera is focusing on that spot and consider everything inside that square as being on the same plane. There is no lens with that shallow a DOF at that distance! Now, if you zoom in and now your subject's face is closed enough that your focus square is the size of the eye, focus on the eye - your DOF at the zoomed in distance is shallow enough to make a difference between focusing on the nose or the eye or the ear - so that face that the little focus square stay the same size is by design and a good thing!
Hope that makes sense.

 

[gohan2091]

Alright, you are over thinking this At that distance when your little focus square covers the whole face, it doesn't matter if you are focusing on the eye, the nose, the ears or the neck!!! Think of depth of field (DOF) as a percentage of the distance from the subject.
If you are shooting a face 5 feet away, and the head is a foot deep, focusing on the eye (with a big aperture) will put the ears and maybe even nose out of focus. See the depth of the head is 1/5th (20%) of your distance to the subject. Now, move the subject to 50 feet away - your focus square will cover the face but the depth of the head is only 1/50th (2%) of your distance - so it doesn't matter if you are focusing on the nose or the ears; everything on the face is considered the in the same plane - the fact that the focus square remains the same size is telling you that the camera is focusing on that spot and consider everything inside that square as being on the same plane. There is no lens with that shallow a DOF at that distance! Now, if you zoom in and now your subject's face is closed enough that your focus square is the size of the eye, focus on the eye - your DOF at the zoomed in distance is shallow enough to make a difference between focusing on the nose or the eye or the ear - so that face that the little focus square stay the same size is by design and a good thing!
Hope that makes sense.

Hello, I understand, thanks for explaining.

 

[Nathan Lanni]

I have been shooting all day with my D7100 and 18-140 zoom. I left it on Full 51pt auto focus just to see how it did. If you watch where the boxes light up it was hitting everything just right. Also the focus was spot on when I went to edit them. In the past I have always used spot focus and may go back to it but it was nice to know the 51 pt auto focus is there if I need it.

Nice photo Don,

I'm curious to know a little more about your photo and if you did any post processing and is it cropped.?

This Thursday I'm taking my d7100 in to the Nikon Service Center here on the west coast to have them look at my autofocus - I think it may be focusing to the left or a little high. There are times when I can images of fantastic IQ but more often it's a little off the mark.

Thanks

Nate

 

[Don Kuykendall_RIP]

Nice photo Don,

I'm curious to know a little more about your photo and if you did any post processing and is it cropped.?

This Thursday I'm taking my d7100 in to the Nikon Service Center here on the west coast to have them look at my autofocus - I think it may be focusing to the left or a little high. There are times when I can images of fantastic IQ but more often it's a little off the mark.

Thanks

Nate

I don't remember if it was cropped that much or not right off hand. The Eagles are very close to where I am standing. And yes, I do post processing on every photo I put up here.

 

[Nathan Lanni]

I don't remember if it was cropped that much or not right off hand. The Eagles are very close to where I am standing. And yes, I do post processing on every photo I put up here.

Yeah I think just about everyone does PP these days, but I don't think I stated my question correctly.

I trying to determine if my d7100 is having an autofocus issue. You may remember that about 6 months I had to have Nikon repair my d7100 because I dropped it. They claimed they fixed everything it but I'm not so sure.

Here's the jest of it: Your photo has excellent IQ so I looked up your AF-S 18-140 on DXO Labs and they rate it a 16 on the d7100. I then compared your image to as couple of mine using a lens DXO Labs rates as a 21. I know there's a lot more to it than just the lens - ISO, shutter speed, aperture, lighting, etc., but frankly I think your image has better sharpness than mine typically do.

Anyway I appreciate your help. My camera will be with Nikon tomorrow so we'll see if it's the gear or just me.

Thanks again.

Nate

 

[Patrick M]

My D7100 is now having focus problems too. In auto it focuses fine with the shutter button half pressed, but then just as I'm about to depress fully, it snaps out of focus. Does this with both my short zooms, so it me or the camera. I'm using A and S while today mostly P. The only things I changed were ISO and exposure as it was bright, with cloudy spells, and I was in woodlands just full of daffodils. Darn irritating.

 

[Horoscope Fish]

My D7100 is now having focus problems too. In auto it focuses fine with the shutter button half pressed, but then just as I'm about to depress fully, it snaps out of focus...

Which AF-mode are you using: AF-A, AF-S or AF-C?

Can you tell if this problem occurs in just one mode, or all three or what have you?