Focusing and Sharpness problem in Nikon 18-55mm f3.5-5.6

[indrajit]

<p>Hello again!<br>

I am using my Nikon D100 for about a year and now I notice that most of the pictures lacks sharpness and focusing problem. I shot using Nikon 18-55mm f3.5-5.6 kit lens. All the pictures are taken in AF mode and the focus point is at the centre. But when I zoom 100%, I find the focus point is out of focus. Here is some sample pictures. Please tell me whether the lens or me that makes the fault.<br>

Thanks.<br>

IC</p>

<div></div>

[ariel_s1]

<p>I see a very deep depth of field, so I don't think that missed focus is the problem. Rather, you are getting softness due to diffraction. Don't shoot at f/14, try opening your lens up a little more. You will get softness in your image if you use f/11 or more, but try to stay at f/5.6-f/8 for better sharpness. Also, shooting wider open helps keep your shutter speed up.</p>

[LenMarriott]

<p>Indrajit, Your EXFI data shows this one taken at 1\125 @ f7.6 and 50mm (82mm FF equiv) Could be camera shake if a tripod wasn't used. Depends on how steady your hands were at the time of exposure. Any camera shake will be exaggerated at the tele end of the zoom. I would want to do further testing using a tripod. That said, this one responds well (to my eye) to some sharpening in Photoshop. Your call. Best, LM.</p><div></div>

[Tim_Lookingbill]

<p>Lot of busy contrast textures for the focus point to keep refocusing as you press the shutter button.</p>

<p>I'ld suggest you assign a separate button for focus off from shutter activated. You'll have to find this within your own incamera settings. Once done you can lock focus and recompose without any unexpected changes to intended focus.</p>

<p>The issue about this is that you can't hear the slight micro focus adjustments the auto focus lens makes when pressing the shutter so you think you've nailed focus when in fact the focus meter has just found another spot to refocus on with the slightest movement by the user especially in the type of high texture shot you've posted.</p>

<p>With my own Pentax K100D DSLR I'm amazed how sensitive the camera sees things with regard to focus compared to what my eyes see.</p>

[lachaine]

<p>This is a lens which can be very sharp at times, and comic-bookish at other times. I haven't done any precise testing on a brick wall, but it seems to me from using it to take pictures that it's sharper when focused closer, and it degrades when subjects are farther, or when zoomed in to the longer end of the range. As said above, it's also a slow lens to begin with, and even slower at the telephoto end. It doesn't take much to exaggerate the effect of camera shake at telephoto distances and even mores so with the necessary slower shutter speed. Despite what you can read about shutter speeds, 1/125 is not really enough for sharp handheld photography. Try doing things so you can use at least 1/250.</p>

[Tim_Lookingbill]

<p>Just a caveat about assigning separate focus button. You'll have to switch back to shutter activated when shooting sports type event where the subject is moving very quickly where you'll miss the shot due to the delay of separate focusing other than shutter activated.</p>

[Tim_Lookingbill]

<p>I don't think it's a telephoto induced issue. My Pentax 18-55mm kit nails sharpness most of the time especially in the type of lighting shown in the OP's posted image. There's enough contrasty edges for the focus meter to deliver adequate sharpness. If shooting jpegs, just adjust incamera sharpness rendering.</p>

<p>A telltale sign to look for you didn't nail focus but compensated off focus by over cranking incamera sharpness is the odd looking thick halos viewed at 100%. I get that on my camera. Most often you'll have better results doing the sharpening in post using better sharpening algorithms. I'm sure it varies between camera brands.</p>

<p>You can always do a focus test to see if there may be something wrong with the lens or if you can tune the focus with the camera body. There's settings and procedures for doing that with some cameras.</p>

[fmueller]

<p>An important point is that you have to use sharpening at some stage between pressing the shutter release and presenting a jpg on the web. If you are shooting raw or have sharpening disabled in the camera, and never use sharpening in post processing, your jpgs will look blurry, even if taken with the best lens and perfect technique.</p>

[ariel_s1]

<p>Does someone else mind rechecking the EXIF data on this image? I'm showing the photo taken at f/14, aperture priority mode with a D3100, saved straight to jpeg in-camera. Regardless, 1/125s shutter speed with the kit lens at any range is not enough to blur the image unless VERY poor technique was used, and I'm not seeing any camera shake in the photo anyway.</p>

[Tim_Lookingbill]

<p>Nice catch Ariel. I saw the OP's mentioning using a Nikon D100 thinking it had only 6MP resolution over the D3100's 14MP.</p>

<p>But f/14 on a kit lens isn't going to give the best sharpness due to diffraction. At least my kit lens doesn't give very good results at that aperture setting.</p>

[john_tran14]

<p>It seems to me that the camera focused on the kid who is the closest subject in the scene</p>

[indrajit]

<p>First, I apologies that I have wrongly mentioned D100. Actually it is D3100 indeed. (The numeric key 3 on my keyboard has a problem and I overlooked it.) I'm really sorry for it.</p>

<blockquote>

<p>saved straight to jpeg in-camera</p>

</blockquote>

<p>No! I shoot in RAW and convered in jpg in LR.<br>

Form your discussion, I found that the problem is lack of sharpness rather focusing.</p>

[ariel_s1]

<p>Oh, well it is a combination of two things, if you shot RAW. I guess my EXIF reader tells me the current compression format, rather than the format used when shot, thanks for the clarification. Still, my first post in this thread is the main reason. Look up "photography diffraction" in Google and all your questions will be answered. Do not shoot at apertures past f/11 if you don't want this effect to occur. In addition, did you sharpen your RAW in post-processing? If not, that compounds the issue.</p>

[LenMarriott]

<p>Indrajit, Thanks to Ariel for keeping things honest. It was indeed f14! Where did f7.6 come from? Guess I need more practice reading EXIF data. ISO 200 on a sunny day with a normal scene should have alerted me that my calculations were bogus. That said there are lots of valuable insights above to contemplate. I know that if I am hand holding a shot 1\250 sec. is what I need to pull it off most times. Anything lower is riskier. Happy snapping. Best, LM.</p>

[leicaglow]

<p>I was sorely disappointed with my 18-55mm lens (the first version of the lens anyway). I ended up buying the 18-35mm and it was far superior. I just couldn't get sharp images from the 18-55mm, it lacked contrast, and colors tended to be greenish/blue.</p>