Let’s say you’re having a hard time getting sharp images with your new DSLR. After getting my Nikon D7000 I was starting to hear complaints from other photographers who claimed they were having focus problems with this camera. So, after doing research, I discovered many people were having focus issues, not just with the Nikon D7000 but other models and brands as well. In fact, focus problems were even evident in the days of the view camera, when it was discovered the film holders were out of spec with the ground glass on certain cameras. The problem of images being out of focus at the film or the sensor plane is as old as photography itself.
There are many things that can cause an images to be out of focus or blurry. In fact, one can probably write a book and go into great detail about the mechanical aspects that can cause focus problems that would include an auto focus system to struggle to find focus, or the auto focus system may not be mounted exactly where it needs to be and may be out of spec or alignment. There can also be small variations in the lens to sensor distance, the lens mount may be slightly deeper or shallower than spec, the mirror in an SLR may not come to rest in it’s exact position. With the combination of manufacturing tolerances of camera and lens design the list goes on and on.
However, before we go blame the manufacturers, many focus and blur problems are caused by user error. What did I just say? Yes, user error! You, me, anyone of us, some of us, even all of us have at some time or another misfocused, or how many times have we shot outside the capabilities of the camera or lens. What about image blur? When we shoot at incorrect settings, using improper tools & techniques causing motion blur when we were after a tack sharp image.
There are so many variables that can have an effect on how sharp your image will be, so let’s discuss some of the things you can do to assure you’re doing everything possible to come up with a sharp image. Please understand that some knowledge in basic photography may be of considerable help and should be understood such as f-stop, shutter speed and how it relates to the image.
1. Keep in mind that your f-stop (lens opening) determines your depth of field and is even more apparent when using telephoto lenses. As an example, an 85mm f1.4 lens has a very shallow depth of field so focus is critical. You may want to stop the lens down a bit, say to f2.8 or more, if you need a greater plane of focus such as if you are photographing two people.
2. Check that the distance you are shooting from is within the minimum focus range of the lens. (Minimum Focus Distance 4.6 ft. (1.4m) of 70-200mm). As Clint Eastwood said, “A good man always knows his limitations”. I think he was referring to photographers, knowing the minimum focus distance of their lens.
Camera Shake and Motion Blur
3. Camera Shake
When it comes to camera shake it means the camera is not being held steady by the photographer. This is very apparent when using slower shudder speeds. Even though you may think the shutter speed is set fast enough but one little jerk at the moment the shutter is depressed and surprise, you end up with a blurry image. The degree of blurriness is determined by the amount of camera shake or movement. I believe this to be a major problem and bad habit when watching some photographers jerk the camera as they press the release.
Vibration Reduction on Nikon lenses and Image Stabilization on Canons may help but even then you have limitations. I remember when I was first studying photography, I learned of different ways to hold your camera steady, even held my breath as I pressed the shutter release button, something I do even to this day. With technology improvements in being able to use high ISOs has really helped but camera shake is still evident in many images I see today. Another way to eliminate or reduce risk of camera shake is to use a tripod or monopod.
Another possibility to eliminate unsharp images is to use mirror lock-up. In a nutshell, this is a practice where one presses the shutter release which moves the mirror out of the way before the actual exposure is made. Then the mirror returns to its normal position after the exposure is made. Some tests show no difference in sharpness but it could be a benefit in doing night photography or longer exposures.
4. Motion Blur
This is another reason why images do not appear sharp. It is evident more among beginner or amateur photographers. Now, I realize sometimes image blur has it’s advantages and is appropriate to give the images it’s impact, if that is what you are trying to accomplish. But, image blur should not be the result of incompetence.
There are many ways motion blur can be used in creating a dynamic image. A good example would be when a part of the image is in focus while another part goes blurry. Panning would be an example when photographing sports to convey a sense of speed such as an automobile race. The photographer uses a slow enough shutter speed while panning (following) the automobile while the background blurs and gives us the look of motion.
Another good example would be waterfalls as water has the look of motion because it is moving and by using a slow shutter speed and a tripod, the resulting image conveys the look of water flowing as the surrounding bank and trees remain still and in focus.Just as motion blur can be effective in some instances, it could also be unsuccessful if not controlled correctly. So, in a nutshell, if you are after tack sharp images, be sure to set your lens speed fast enough to freeze the action and if needed, use a monopod or tripod for smooth panning.
If you have mastered the above techniques and you are sure the unsharp image problem is not the operator, then you may have a defective DSLR or lens that needs to be repaired or recalibrated by the manufacturer. Most likely this would not be the case but could be a possibility. A greater possibility, however, would be since most lenses are massed produced there may not be a perfect match with your camera body causing manufacturing tolerances to be slightly off or slightly out of calibration. If that is the case, then you may want to check your auto focus by doing a test then if necessary, an AF fine tune adjustment.