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I have a 3 month old Nikon D5100. The closer I zoom in, the blurrier the picture. This is on auto. I have two lenses and they are both doing this. Any ideas why?

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Please post a link to an example of an image this issue. You can do this with a website like imgur or dropbox. Once you get more reputation on this website(>10 rep) you can post images directly here. If this is not possible we most certainly will need to know the settings of the camera when one of these images were taken(shutter speed, ISO, aperture, lens, etc.). Thanks! –  dpollitt Apr 7 '13 at 23:55
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The reason we need an example photo is that there is more than one type of blur, and looking at an example photo would probably tell us which type of blur it is instantly. Types of blur include: focus not on subject; subject motion blur; camera shake; and more. –  thomasrutter Apr 8 '13 at 3:07
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Another question, when you say it is on auto, is this the M/A switch on the lens itself, or the dial on the camera? It's the switch on the lens itself that is relevant here. –  thomasrutter Apr 8 '13 at 3:09
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If no example image is posted, at what point would this community like to just turn this into a broad "Why is my image blurry?" question? It has been 24 hours... –  dpollitt Apr 8 '13 at 23:41
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It might not have helped that when the questioner was at a rep of 11 (enough to post an image) someone down voted the question and dropped her back to 9 (not enough to post an image). –  Michael Clark Apr 9 '13 at 0:40

4 Answers 4

Without seeing an example image, it's hard to tell which of the following is the problem.

  • Your lens is on manual focus.

    Note that having the camera's exposure dial on the green "Auto" is not the same thing as auto-focus. Auto-focus is usually controlled on the side of the lens itself with an "A/M" switch.

  • The subject is moving too fast for your shutter speed.

    If you are photographing a person, use a shutter speed of 1/250s or faster. If you are photographing a fast-moving person such as a kid, animal or sports, use 1/500s or faster - that is, if you want to eliminate motion blur.

    If you cannot get to this shutter speed, you probably need more light or a lens that can open to a wider aperture.

  • The camera is shaking.

    If your shutter speed is too slow, even the small movement of your hands on the camera can cause blur due to camera shake. As a general rule, avoid using a shutter speed slower than 1/50s, or if you are zoomed in (telephoto), avoid using a shutter speed slower than 1/(focal length), ie 1/135s if you are zoomed in to 135mm.

    If you cannot get to this shutter speed, you probably need more light or a lens that can open to a wider aperture.

  • Subject is moving out of focus.

    If the subject is moving, then they may have moved out of focus in between the time the autofocus mechanism focused, and the camera took the photo. This is particularly true if you are very close to the subject and they are moving fairly fast toward or away from you.

    Try to get your subject still, or use a wider shot. Some cameras are faster at focusing and exposing than others.

  • You haven't focused on the subject.

    Cameras will only focus on a certain part of the image at once. In full auto mode, it usually picks an area to focus intelligently, which works most of the time but sometimes picks the wrong part of the image to focus on.

    The quickest fix to this is to half-press the shutter to focus while directly pointing at the subject you most want to focus on (most cameras give emphasis to what's in the middle of the frame), keep it half-pressed, and then move the camera to take the picture you originally wanted, then fully-press the shutter. You can also set the camera to choose a specific focus area instead of choosing one automatically, which will make this technique even more effective (and necessary).

  • The subject is too close.

    The lens has a limit to how close you can take photos. This is probably only going to be the case if you are extremely close, say less than 12 inches from the subject on a typical lens. Some lenses can focus very close, say 4cm (2 inches). Others designed for viewing distant objects may have trouble below 2 feet.

    Normally if this is the case, there will be a light or beeping noise (or different/lack of beeping noise) to indicate the autofocus failed.

  • There is not enough light for the autofocus to work well.

    In dark environments such as a dimly lit room, the autofocus sensors in a DSLR may not work as well, may work more slowly, or may not work at all. Even in situations where there is enough light to take a photo (say, using a high ISO or using a flash) there still may not be enough light for the autofocus sensors to work well.

    Many cameras have an autofocus-assist light (orange or red light coming on during autofocus) which you can enable to help with this in some situations. Again, the camera should show a light, or beep (or not beep/beep differently) to indicate that the autofocus is having problems.

    Bonus hint: some cameras have an autofocus sensor in the centre of the frame that is better able to cope with low light than the surrounding autofocus sensors. Try lining up your subject in the centre of the frame on half-press, if you're in a dark environment.

  • The autofocus mechanism in the lens is faulty.

    It's unlikely, but it's possible that the lens focusing mechanism has dirt in it or is jammed. Switch the lens to manual and see if it turns smoothly and freely. If not, it's one sign that there could be something wrong with the lens that would require taking it back to a camera shop.

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Without seeing any sample pictures, it sounds to me like you are having issues with camera movement. The longer the focal length of the lens when you take a picture, the greater effect the same amount of camera movement will have on blur. With many zoom lenses the closer you zoom in, the narrower the maximum f-number will be for the lens and the slower the shutter speed is needed for proper exposure.

There are a few things you can do to reduce the amount of camera movement and the effect it has on your pictures:

  • Use a faster shutter speed (Tv). This probably means taking the camera out of Auto and learning how to use one of the P A S M modes. The old general rule of thumb was to use a Tv no slower than 1/focal length when shooting handheld. With the emergence of DSLRs with sensors smaller than a frame of 35mm film the sensor size must also be taken into account. With your D5100 the sensor has a crop factor of 1.5x, so the formula for the minimum Tv should be 1/(1.5 X focal length). If your lens is at 200mm, that means a Shutter speed of 1/300 second or faster. At 300mm, you need a Tv of 1/450 sec or faster. With a 55mm focal length, 1/80 sec. or faster should work.
  • Increase the ISO sensitivity your camera is using. Most cameras will produce the best image quality (IQ) at ISO 100. Increasing the ISO sensitivity will allow you to use faster shutter speeds at the same aperture, but this will also increase the amount of noise. Your D5100 has pretty good noise reduction (NR), but the higher the ISO setting, the more NR needs to be applied and this affects the overall sharpness of the image.
  • Increase the size of the aperture. The lower the f-number, the wider the aperture. A setting of f/2.8 lets in twice as much light as f/4, which in turn lets in twice as much light as f/5.6. The more light you allow in, the faster the Tv you can use with the same ISO setting. That is why lenses with maximum apertures of around f/2.8 or wider are referred to as fast glass. In the case of kit lenses that come with many cameras, the problem is that at the widest focal lengths they can only open up to f/3.5 or f/4 and at the longer end they are usually at f/5.6.
  • Practice good camera stabilization techniques. Hold the viewfinder up to your eye and keep both elbows in as close to your body as you can. Support the camera with your left hand under the barrel of the lens. Forget the "dirty diaper" grip you probably used with a compact camera. Live View on a DSLR is meant for use with a tripod. Stand with your feet apart and one slightly ahead of the other. Take a deep breath and exhale slowly, taking the shot just before all the air is gone from your lungs. Lean against a sturdy wall, tree trunk, building support pole, etc. to help stabilize your camera.
  • Use Vibration Reduction (VR) if your lens has it. This will allow you to handhold 1 to 3 stops slower than the 1/focal length rule. You will still need to practice good camera stabilization techniques to get the benefit of VR. If you are using a focal length of 200mm, you can now use a Tv as low as 1/80, 1/50, or even 1/40 seconds.
  • Use a stable platform to support your camera. Normally this means a tripod, but you can also use a bean bag on a table or even set the camera directly on a stable surface if it will point in the direction you wish. Activating the shutter via the self-timer or a wired or wireless remote will enable you to use the tripod to its full potential. When a tripod isn't practical or allowed, a monopod can be very helpful and buy you a few more stops.
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Note that vibration reduction does not help subject movement, only camera shake. If you are photographing a person and it's not a studio model shoot, you'll still need 1/250s or 1/500s if they're moving to capture them and minimise motion blur. Vibration reduction is good for situations where camera shake would be a worse problem than subject motion, such as when using a long telephoto lens (which, to be fair, is the example scenario you gave). –  thomasrutter Apr 8 '13 at 5:10
    
This entire answer addresses camera movement, not subject movement. The fact that the pictures are blurrier the closer the original questioner zooms in indicates camera movement issues, not subject movement. But I often shoot people at Tv well below 1/250s. You just need to time the shutter to the right moment. If a person is jumping, catch them in the instant they stop going up before they start back down. Catch the conductor of the orchestra the instant his baton reverses from right to left to left to right. 1/500th will freeze all but the fastest athletes in a full speed run. –  Michael Clark Apr 8 '13 at 8:25

D5100 is a so-called Crop camera. This means that the rule of thumb to ensure that the shutter speed is 1 / focal length needs to be adapted into 1 / 1.5*focal length. So if you shoot at 18mm, you need the shutter to be 1/27 at least. If your hands shake more than average, or your target is moving, you'll want to double that or make it even faster.

If you zoom in to, say, 50mm, you need 1/75 at least.

If you then zoom in to, say, 135mm, you need 1/202 at least.

This is not all there is to it.

If you are using a low end , or midranged zoom lens, and auto exposure. Which is very likely if you just got yours first DSLR, using kit lens and maybe a cheap zoom to go along with it? Then your lens is not a fixed aperture lens, but an F3.5-5.6 lens.

The effect of this 3.5-5.6 aperture is that the fastest aperture (the size of the light tunnel) will shrink as you are zooming in from 3.5 to 5.6, almost quadubling the exposure time, so if the light is enough to make the shutter speed 1/100 at 18mm, which is more than enough, it is only good enough to make the speed 1/35 at 50mm on your kit lens. And you need it to be at least 1/75.

A third issue that might be the case for you is that the depth of field - which is the depth of the infocus subjects as a function of distance from you narrows down as you zoom in. The fact that the aperture gets darker, it counters this effect a bit, but at 2 meters distance, the DOF narrows from 18mm F3.5 DOF=2.15meters, to 55mm F5.6 DOF=0.29meters. This adds pressure on your AF focus mechanism, which btw is seriously limited at F5.6. They work best up to F2.8 and doesnt work at all above F5.6. Looking through your viewfinder, everything might seem in focus, but on the picture it really isn't. So your system is really pushed to its limits here.

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+1 Exactly my thought process on why this is a camera movement issue. Longer focal length + slower Tv due to smaller aperture = more blur. –  Michael Clark Apr 9 '13 at 0:48

I assume your lens is set to 'Manual Focus' (not camera). You need to play around with the focus ring to focus. you'll find the manual A-M switch on the lens near the white mark when you attach your lens.

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