will increase depth of field also decrease sharpness?


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darrrrrrrrrr

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Sep 19, 2006
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#2
stopping down from wide-open will improve overall lens sharpness. after a certain point, diffraction effects will diminish overall sharpness.
 

night86mare

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#3
sharpness overall and/or sharpness of the focal point? :think:
depends on the lens, only lens test will be able to tell you for sure.

but few lenses are at their sharpest wide open. stopping down 1 -2 stops usually renders exponential sharpness.

for most lenses, beyond f/16 you get degradation of sharpness, due to the diffraction thing that darren has mentioned.
 

baggiolee

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Dec 7, 2006
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hmmm icic. thx! i'm using nikkor DX 18-55mm VR lens...maybe i shouldn't go beyond f/12 to be safe.
 

Dec 28, 2008
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#6
i read that my 18-55mm IS is most sharp at f/8 - f/11 ... however I would like to ask if the sharpness difference very obvious if lets say I compare an f/8 shot to like f/16?

i initially had the wrong impression that stopping down to like f/18 would give me sharper images :(
 

thenomad

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#7
How far you can stop it down depends on how dense the pixels are.
The denser it is, the less you can stop it down.
So I believe, full frame sensors allow stopping down more than sub-frame.
 

giantcanopy

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Feb 11, 2007
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#8
It is a tradeoff . But I would not lose too much sleep over the percieved slight drop in sharpness if I needed the dof. I have done f16 a plenty on the APS-C too.

Ryan
 

Dec 28, 2008
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#9
It is a tradeoff . But I would not lose too much sleep over the percieved slight drop in sharpness if I needed the dof. I have done f16 a plenty on the APS-C too.

Ryan
ah cool thanks for the answer. i guess i am more curious about how much of sharpness do i really lose. if i may, lemme use examples. these 2 shots were shot at f/18.





im still kinda learning from all these, so the question here would, are these pictures considered sharp enough? and would it have been better stopping them up to f/8 and f/11?

thanks!

----

* have posted the larger versions of the pictures, sorry about that!
 

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Blur Shadow

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Sep 17, 2005
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I doubt any CSer can comment much on your picture, since the resolution is currently 730 x 487.

You can have a look at it yourself. Honestly, you'd have to view your picture at 100% or more, or print at S8R or more to tell the difference. You can barely spot the difference if you tend to post small 600 x 400 pictures online or print 4R.

If you'd really like to have some comments from CSers, please don't post a full size 12MP picture either; just provide a 100% crop of a portion of the picture. (typically an area with a lot of details)
 

thenomad

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#11
If most of the subjects in your frame are on more or less the same plane, then you don't need so much DOF. In this case around f/8 is good for maximum sharpness.

But if you have subjects in the foreground and background, and they are quite far apart, you'll notice how far the DOF goes in the frame. Sometimes the background is not sharp, or sometimes the foreground. In this case you probably need around f/16, more or less depending on the subjects.

If you want to check whether you have enough DOF, have a look at the extreme planes, i.e. extreme foreground or background. If they get sharper when you stop down your aperture, that means you gain in sharpness due to the increased DOF.

If you stop down and you don't get increased sharpness, that means you have enough DOF to cover the entire scene.

Play around with the aperture to see which setting is just right for the particular scene. That way you can maximise the balance between DOF and sharpness.
 

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