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Thread: what's wrong with these photos?

  1. #1

    Wink what's wrong with these photos?

    I'm looking to take a picture of everything that is sharp, so I tried turning up the f stop (increasing the number) but still it isnt very sharp.

    My setup: Nikon D90 with kit lens
    Took at my HDB neighbourhood at 10am.

    Click the following pictures to expand.


    Looking from bottom, it still seems fine, but as you progress to the top, it starts to blur out.
    F number: 20
    Exposure: 1/40
    ISO: 100


    Focal length: 18
    Exposure: 1/40
    ISO: 100
    Only car seems to be in good focus, but I would like everything to be in focus.


    Many thanks!

  2. #2

    Default Re: what's wrong with these photos?

    not sure what f stop the kit lens is sharp at, but a good bet will be f/6.7 - f/11.

    beyond a certain point, something called DIFFRACTION sets in, and your image starts to soften despite your getting more DOF.

    you can wikipedia this effect, it is well documented.

    for first picture, i don't see what you mention, what top begins to blur out.

    for second , looks like corner softness problem. go and google what this is about.

  3. #3

    Default Re: what's wrong with these photos?

    my advice is to learn proper composition, and then you will realise that most of the time, in well composed pictures, nothing of much importance is going to be at the corners.

    so it is a much smaller issue than you think it is.

    also, sharpness is overrated.

  4. #4
    Senior Member
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    Default Re: what's wrong with these photos?

    Is these taken with a tripod or handheld?

    If handheld, with the shutterspeed of 1/40, there will be handshake. Try using a tripod.
    Also with such small aperture, diffraction might occurs which affects sharpness.

    Bottomline is, use a tripod, use the correct aperture and can apply some USM in Photoshop to sharpen the image further.

  5. #5

    Default Re: what's wrong with these photos?

    Hi Hyperous,

    Your foto is plenty sharp. Using Kit Lens, one cannot expect perfect clarity across the frame. Even wif expensive L lenses, u still get distortion at the edges.

    Some points to note:

    - Use a higher shutter speed maybe 1/80 or 1/100. (Actually, your 1/40 is shutter speed, not exposure, exposure is what u get factoring the shutter, aperture & ISO).
    - Use a tripod if u prefer 1/40 shutter.
    - Use a prime lens, tamron 17-50, 17-55, 10-22mm or other lenses well knowned for sharpness.

    Hope the above helps.

    Mettalife
    http://www.mettalifephotography.com/

  6. #6

    Default Re: what's wrong with these photos?

    The picture is actually sharp, it is just that the resizing has probably caused the image to soften. Do another slight sharpen after resize.

  7. #7

    Default Re: what's wrong with these photos?

    1st photo: top is extremely sharp. I can easily see the lines of beams and aircon unit.

    2nd photo: I'm guessing if you do a 100% crop of both the car tyre rim, and the block number, you will find that both are similarly sharp.

    Try to find the sweet spots (best performance) of your particular lens at different focal lengths, and if you're methodical, under different conditions (low contrast, evenly lit scene / medium contrast scenes / high contrast front and backlit scenes). That way you will have a database of your lense's strengths and weaknesses at different focal lengths, apertures and under what sort of conditions. The key word is 'Methodical'. But if you're not so inclines, just try to be more observant and remember how your lens performs in general.

    I won't pretend to be an expert on composition, but I would say that if you shoot and learn more, you would realize that corners and sides can also be used effectively to improve or add interest to a composition. In most situations, you want to avoid placing a subject in a corner, but in others, you may deliberately want to place a prominent or supporting subject/object right into a corner/side of a frame, and that's where a lens' corner performance can be vital.
    Last edited by Dream Merchant; 20th October 2009 at 06:06 PM.

  8. #8

    Default Re: what's wrong with these photos?

    1/40 is the problem.

    use a shutter speed about 1.5 to 2 times of your middle focal length for picture to be sharp - thats the rule i follow.

    e.g middle focal length of 18-55 is around 35 so at least 1/60 or faster

    or use a tripod

  9. #9
    Deregistered shaoken's Avatar
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    Default Re: what's wrong with these photos?

    Sorry, OT a little.
    From the pic, these shots are taken @ Clementi/Dover area.

  10. #10

    Default Re: what's wrong with these photos?

    Quote Originally Posted by hyperous View Post
    Looking from bottom, it still seems fine, but as you progress to the top, it starts to blur out.

    Only car seems to be in good focus, but I would like everything to be in focus.


    Many thanks!
    From your post you seem to be suspecting a depth of field issue. While reducing the the aperture increases the dof, you can only do so much if the objects are at widely different distances.

    You can try the hyperfocal distance http://www.dofmaster.com/hyperfocal.html to get as much dof as possible but there is a limitation if the nearest object is very near. Otherwise you should focus somewhere inbetween the nearest and furthest point that you want to be in focus.

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