Sharpness and exposure on D90 : 18-200

Discussion in 'Nikon' started by andiamo_s, Oct 21, 2014.

  1. Am started to get a little concerned about the sharpness of the shots I am able to capture on a recently procured preowned 18-200 lens.

    Irrespective of Shutter / Apperture / Manual modes used, shots get hazy especially under low light conditions.

    Getting diffucult to maintain the low ISO while still giving enough exposure time to get a crisp shot. Bumping apperture width or shutter time is not helping on many occassions.

    Below are a few samples which have started me to get concerned
    The 3rd shot showing the SF Bay Bridge has by far been the softest I have seen under reasonably good conditions a few minutes pas sunset.

    The last two shots for instance wonder why everything else but the numbers 7,8 are darkened out.

    The shot before, the letters in BLUE that I can focus and read clearly on my 50 mm lens is not seen one bit when I set it to the same focal length on the 18-200
    Is it something with my settings or the lens that's giving up... confused !
    Any help would be appreciated !
  2. What tripod & head were you using for these shots?
    Kent in SD
  3. What tripod are you using? If none, the question is answered.
    EDIT: Kent and I posted at the same moment.
  4. None, I was'nt using a tripod for any of these shots. But did have VR enabled, was hoping to atleast get better sharpness on the images.
    Have had the opportunity to take a few sharper shots under similar conditions elsewhere using an 18-200 I had rented earlier.
    Wonder if softness and lack of sharpness could solely attributed to the tripod alone. Just need to make sure there's nothing wrong with the front elements or my settings or the camera configuration per se.
    Thanks for your advise.
  5. These look normal for that lens, camera and no tripod. You're not going to be able to get good image quality in dark
    conditions because the small aperture will force you to use slow shutter and/or high aperture, and the combination of the
    small aperture and the AF system that's not incredibly sensitive is going to lead to missed or imperfect focus.
  6. your bridge shot is 1/80 and 5.6. in those exposure conditions you needed a longer exposure and a deeper DoF, which necessitates a tripod. VR will help with camera shake but wont let more light into your camera, and the 18-200 is at its sharpest at f/8-11. the previous shot, of the houses on the hill, is indeed hazy, but that could be atmospheric haze or fog from shooting at long distance. also f/14 is an aperture at which sharpness will be reduced due to diffraction. there's no EXIF on the first shot, but it looks reasonably sharp for that lens, and suggests haze or fog could indeed be the culprit for the similar shot. as for shot #4, it's just too dark. you would have needed a much slower shutter to capture anything there, since you're wide open at f/4.5 and ISO 1600. ditto for #5.
    The last two shots for instance wonder why everything else but the numbers 7,8 are darkened out.​
    either there's reflective material on those signs or they're illuminated.

    the last two photos look better because the lighting and framing are better. conditions are different enough though. the hillside shot is at base ISO, a reasonable aperture, and a fast shutter, with focus squarely in the foreground. and it looks like there's more illumination on that building in the other shot. incidentally, looked at some shots with your 50mm on your flickr photostream. that lens looks sharper because it is sharper. the 18-200 is an 11x zoom which trades sharpness for convenience; it will never match the 50 for sharpness at common apertures.

    if i were you'd i'd test your new lens in more favorable lighting conditions, with a tripod. it is possible you got a dud, but it's not possible to know that for sure, based on those shots.
  7. The 18-200 was a very competent lens on my 6MP D50. As soon as I upgraded to a D90 I relegated the 18-200 to the D50 only and then eventually sold it.
    The softness above 135 at every aperture (yes, it's best between f8 and f11) is always there. AT 50mm it actually isn't so bad, but your 50mm prime will kill it every time.
    That said, if you add a tripod, you might find that the photos are okay for whatever you are going to use them for, but in this case only if you use a good solid tripod.
    In short, for sure, you need a tripod and probably careful manual exposure to take these kind of night shots.
    How big do you print, how tight do you crop, how are you going to use these photos?
  8. May I add one comment? Have you ever had your D90 in for a check up?
  9. You have bad vignetting in the 3rd shot. Do you have the hood on wrong or using one or more filters?
  10. Testing lens sharpness in darkness or complicated light conditions doesn't really reveal a lot. The second photo in the first post looks like no lenshood, or the sun just striking from front-right, giving the washed-out look. Could also be the effect of a (cheap/bad) filter. The fourth shot looks like a complete mis-focus. In all low-light cases, aperture is wider than ideal (so depth of field might be insufficient). There is more than one single reason why an image can be seeming less sharp - it's more often than not user error, not a lens problem.
    Wonder if softness and lack of sharpness could solely attributed to the tripod alone - Valid question, but until you rule out the tripod (=use one), there is no way to answer. As it is, the lack of tripod is more likely a real problem than the lens is. So, use a good, solid tripod, not a cheap $50 floppy one and test the lens properly (lens hood on, no filters), with good light.
    Overall, your photos are pretty much what I'd expect from this lens. It's a "jack of all trades, master of none"-lens, do not expect it to be as good as a specialised tool (which a 50mm prime is). You have to be realistic about this lens - it's not going to give you the sharpest results, and pixel-peeping it will not hold up as good as some other lenses. You buy this lens for convenience, not because it's an optical masterpiece.
  11. Try to use tripod and no VR, and test again.
    I use to have 18-200mm vr on D200 and was great combo.
  12. It's an 11:1 ratio zoom! How sharp do you really expect it to be?

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