Picture not sharp-why ?


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photo2k

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Mar 29, 2004
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#1
Hello,
I am using Nikon 28-200mm. I noticed that some of my pictures the background scenery was sharp but the subject in front was soft. The picture was taken at 28mm with F stop of 7.1
I am using Aperture Priority. When I was took the picture, I focus on the subject not the scenery. With the same setting, some pictures turn out to be sharp for both subject and scenery.
What have I done wrong ? Hope to get some valuable advise from Gurus out there.

Cheers.
 

VR2

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Dec 17, 2005
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#2
sample of yr pic taken will be great help.. ;)
 

jumbocrab

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Jun 27, 2004
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#3
Yes, show us a picture of what you mean. You should also include some parameters like whether you are using AF-C or AF-S, where is your focusing point etc etc.
 

#6
I believed in your case you were using AF-C, which focuses continually (predictive focusing) on a moving subject. Try using the following technique:
[in AF-S/ Manual mode]

1) Focus on your subject, meter your exposure and press the shutter button HALFWAY. Remember to set your zoom accordingly and "lock" the focal length before pressing the shutter button. To ensure that your exposure stays, use the exposure lock function.

2) With the shutter halfway pressed, the focus should lock. At this point RECOMPOSE your picture/frame and remember to keep the shutter button pressed halfway.

3) Press the shutter fully and behold your beautiful masterpiece on your LCD screen:lovegrin:

Hope it helps. Personally I use the above for most of my composition of pictures. I suggest using f8 or f11 rather than f7.1 as the earlier 2 are the "sweetspot"s of focus.
 

Nikonnew

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May 31, 2005
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#7
Sorry to hijack this thread, for fairly large aperture setting like 4.0, is there a minimal distance that we need to have between the subject and the cam inorder to have a sharp image of the subject?
 

#9
Nikonnew said:
Sorry to hijack this thread, for fairly large aperture setting like 4.0, is there a minimal distance that we need to have between the subject and the cam inorder to have a sharp image of the subject?
It's all dependent on your lens if i am not wrong. Macro lens allows you to go close, normal lens there is a minimum distance at which you can focus on.

To all others, please correct this if it's wrong. I am here to learn to;p
 

westwest1

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Feb 25, 2006
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#10
photo2k said:
Hello,
I am using Nikon 28-200mm. I noticed that some of my pictures the background scenery was sharp but the subject in front was soft. The picture was taken at 28mm with F stop of 7.1
I am using Aperture Priority. When I was took the picture, I focus on the subject not the scenery. With the same setting, some pictures turn out to be sharp for both subject and scenery.
What have I done wrong ? Hope to get some valuable advise from Gurus out there.

Cheers.
NPNT:sticktong Post them or not very hard for people to figure out what you trying to say ya....
 

Nikonnew

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May 31, 2005
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#11
moriahphotos said:
It's all dependent on your lens if i am not wrong. Macro lens allows you to go close, normal lens there is a minimum distance at which you can focus on.

To all others, please correct this if it's wrong. I am here to learn to;p

I was using film cam and does not have a scanner, so would not be able to post any pictures, but theoretically, will there be any diff between the two following situation

Subject is about 5m away

1) F 4.0, 1/1000 s
2) F 8 , 1/500s

The above exposure is only hypotetical,

I understand the latter will give more DOV, so the background will be more in focus, but will this make a diff in the focus of the foreground subject?
 

Artosoft

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Aug 31, 2005
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#13
Nikonnew said:
I was using film cam and does not have a scanner, so would not be able to post any pictures, but theoretically, will there be any diff between the two following situation

Subject is about 5m away

1) F 4.0, 1/1000 s
2) F 8 , 1/500s

The above exposure is only hypotetical,

I understand the latter will give more DOV, so the background will be more in focus, but will this make a diff in the focus of the foreground subject?
First, let me correct you if you don't mind: DoF (Depth of Field). Another one is FoV (Field of View) / AoV (Angle of View).
DoF (Depth of Field): http://en.wikipedia.org/wiki/Depth_of_field.
FoV (Field of View) / AoV (Angle of View): http://en.wikipedia.org/wiki/Angle_of_view.

From your example, yes, aperture give you different DoF. f/4 is more shallow than f/8. While, shutter speed will give no different in DoF.

DoF is govern by 4 factors:
1) Lens' aperture.
2) Focus Distance between camera and subject.
3) Lens' Focal Length.
4) CoC: http://en.wikipedia.org/wiki/Circle_of_confusion.

Hope above help ;) .

Regards,
Arto.
 

Nikonnew

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May 31, 2005
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#14
Artosoft said:
First, let me correct you if you don't mind: DoF (Depth of Field). Another one is FoV (Field of View) / AoV (Angle of View).
DoF (Depth of Field): http://en.wikipedia.org/wiki/Depth_of_field.
FoV (Field of View) / AoV (Angle of View): http://en.wikipedia.org/wiki/Angle_of_view.

From your example, yes, aperture give you different DoF. f/4 is more shallow than f/8. While, shutter speed will give no different in DoF.

DoF is govern by 4 factors:
1) Lens' aperture.
2) Focus Distance between camera and subject.
3) Lens' Focal Length.
4) CoC: http://en.wikipedia.org/wiki/Circle_of_confusion.

Hope above help ;) .

Regards,
Arto.
Sorry if I sounded confused, but I assume a smaller aperture requires a slower shutter speed most of the time??? but I do agree with Ortega, I also feel it might be a focusing problem....
 

#15
moriahphotos said:
I believed in your case you were using AF-C, which focuses continually (predictive focusing) on a moving subject. Try using the following technique:
[in AF-S/ Manual mode]

1) Focus on your subject, meter your exposure and press the shutter button HALFWAY. Remember to set your zoom accordingly and "lock" the focal length before pressing the shutter button. To ensure that your exposure stays, use the exposure lock function.

2) With the shutter halfway pressed, the focus should lock. At this point RECOMPOSE your picture/frame and remember to keep the shutter button pressed halfway.
If you are able to select the focussing point on your cam, do so. ie, if your cam have 7 focus points, select the focus point nearest to the subject, then recompose if necessary.
Focussing is more accurate, IMHO
 

Artosoft

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Aug 31, 2005
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#16
Nikonnew said:
Sorry if I sounded confused, but I assume a smaller aperture requires a slower shutter speed most of the time??? but I do agree with Ortega, I also feel it might be a focusing problem....
That's related to exposure, but not to DoF (Depth of Field).

Regards,
Arto.
 

Artosoft

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Aug 31, 2005
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#17
codling said:
If you are able to select the focussing point on your cam, do so. ie, if your cam have 7 focus points, select the focus point nearest to the subject, then recompose if necessary.
Focussing is more accurate, IMHO
Hmmm...

I don't know about how the rest prefer, but I prefer to put focus point on the center. Half press the shutter release button with the subject on the center, after the focus is achieved, compose the photo. Full press the shutter release button.

Regards,
Arto.
 

yowch

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Oct 16, 2002
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#18
Nikonnew said:
Subject is about 5m away

1) F 4.0, 1/1000 s
2) F 8 , 1/500s

The above exposure is only hypotetical,
Just to point out, F4.0 1/1000 is equivalent to F8.0 1/250 or F5.6 1/500. When we talk about DOF, we should keep the EV constant to simplify discussion.

In any case, go down to a good photo book shop, say Riceball, get a basic book for $30 to $60 and read it all up. That's what everyone should do first.

The focus on subject, lock focus and recompose before shooting routine works well with telephoto range, but at wide angles, you'll have planar differences that will cause off focus. If you get a book and read this up, you'll know what I mean.

And modern matrix metering will be thrown VERY far off with the focus, recompose, shoot routine because matrix metering will take focus distance, exposure of various segments and ambient lighting into consideration. Again, think a bit about this or read up matrix metering to understand more.
 

ortega

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Nov 2, 2004
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#19
Artosoft said:
Hmmm...

I don't know about how the rest prefer, but I prefer to put focus point on the center. Half press the shutter release button with the subject on the center, after the focus is achieved, compose the photo. Full press the shutter release button.

Regards,
Arto.
I do the same, i do not like to let the camera choose the focusing point
it slows me down
 

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