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DPChallenge Forums >> Photography Discussion >> Pictures are not sharply in focus
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 01/19/2007 01:50:07 PM · #1
Picture from my Nikkor 18 - 70 zoom on my D70s are not as sharply in focus as are the pics from my AF Nikkor Micro 60mm f2.8D. Can anyone explain why, and is there anything I can do to make the zoom lens sharper besides changing the settings within the camera itself.
 01/19/2007 01:52:38 PM · #2
most prime lenses blow away zoom lenses. The only ways to maximize sharpness are to use a tripod, use a fast shutters speed, and stop the lens down to the sweet spot which is usually around F8.
 01/19/2007 02:00:31 PM · #3
Most of the Nikon Micro lenses are the epitome of sharpness that is what they are designed for. Hard to compare sharpness against those specific lenses. However, the 18-70 should be plenty sharp enough. Perhaps if you have an example, that might show if there is a lens problem or not?
 01/19/2007 03:15:35 PM · #4
I have actually almost stopped using the 18-70. When I switch from the primes, the 35-70 or 70-200 -> the 18-70 just looks horribly soft. While it actually is a pretty good lens.


01/19/2007 03:19:59 PM · #5
It is a bit soft compared to the 50mm 1.8 for example, but it's not that bad.

I would, however, stay away from in-camera sharpening (if you shoot JPEG). It's much better IMO to sharpen later, not in camera. Your best bet (again IMO) is to shoot RAW, use the F8 - F11 range (where the 18-70 is clearest) and correct for sharpness with software.
 01/19/2007 03:43:43 PM · #6
Originally posted by kyebosh:
most prime lenses blow away zoom lenses. The only ways to maximize sharpness are to use a tripod, use a fast shutters speed, and stop the lens down to the sweet spot which is usually around F8.


So f8 to f11 will be sharper than f25 or higher? I always thought the higher the fstop the better the focus. Or, is it just dof that increases? And, if that't true, what is the difference between dof and focus?
 01/19/2007 03:54:13 PM · #7
Originally posted by cogerox:
Originally posted by kyebosh:
most prime lenses blow away zoom lenses. The only ways to maximize sharpness are to use a tripod, use a fast shutters speed, and stop the lens down to the sweet spot which is usually around F8.


So f8 to f11 will be sharper than f25 or higher? I always thought the higher the fstop the better the focus. Or, is it just dof that increases? And, if that't true, what is the difference between dof and focus?


I'm not going to go in depth into this because there are better people on the forum to explain this. However, "generally" a lens is sharpest 2-3 stops below it's widest aperature. That would put you around f8 for you lens. If you use a 1.2 or a 1.4, sometimes you see the sharpest aroudn f4 or even f2.8. This really varies between lenses.

DOF just determines how much in a given plain is in focus. DOF does not determine sharpness in the truest sense. Higher f-stops will give you more things in focus as far as front to back, but not neccessarily sharper image.

Hope that helps.
 01/19/2007 04:04:47 PM · #8
Originally posted by jaysonmc:
Originally posted by cogerox:
Originally posted by kyebosh:
most prime lenses blow away zoom lenses. The only ways to maximize sharpness are to use a tripod, use a fast shutters speed, and stop the lens down to the sweet spot which is usually around F8.


So f8 to f11 will be sharper than f25 or higher? I always thought the higher the fstop the better the focus. Or, is it just dof that increases? And, if that't true, what is the difference between dof and focus?


I'm not going to go in depth into this because there are better people on the forum to explain this. However, "generally" a lens is sharpest 2-3 stops below it's widest aperature. That would put you around f8 for you lens. If you use a 1.2 or a 1.4, sometimes you see the sharpest aroudn f4 or even f2.8. This really varies between lenses.

DOF just determines how much in a given plain is in focus. DOF does not determine sharpness in the truest sense. Higher f-stops will give you more things in focus as far as front to back, but not neccessarily sharper image.

Hope that helps.


I usually shoot at the highest f stops to get dof. I'm going to try it at the lower stops and see what difference it makes. Thanks for the info
 01/19/2007 04:07:38 PM · #9
Testing focus website. I believe there are other websites listed in the forums but this is the first that I found.
 01/19/2007 04:08:49 PM · #10
One other to mention too is diffraction limits on DSLRs. Generally you will start running into these around f11/f13/f16. Depending on the scene if you shoot higher than these you will notice a drop of in quality no matter the lens. This is strictly a digital sensor issue (due to photosites and what not).
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