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The basics of sharp photos
Article written by Steve
Many people struggle to get sharp photos from their camera and while some would think that it should be quite easy to get a good result every time, when you begin to understand how many things can effect the sharpness you’ll soon see that on the occasions that you do get it correct many factors had to be right and it wasn’t by accident.
In this article I will discuss some of those factors, the ways they affect the outcome and several techniques that should help even the beginner travel the road to pin sharp images.
The first thing to consider is the Focus, it may seem obvious but unless you have perfect focus then everything else will not matter. As cameras become more advanced so do the auto focus systems, however unlike the user, these are not intelligent and cannot think or make a decision.
Do you see the first problem?
If you are photographing a table with three subjects on, we can use a lamp, a flower and a bowl for our example and align them in a diagonal line with the lamp at the front, the flower next and finally the bowl at the back. Now for our shot we want to have the flower (which is in the middle of the other two subjects) in focus then its likely that as most auto focus systems are centre weighted (give more preference to the centre area of the picture) in the majority of cases you will get a good focus lock where you want it and a good result with the flower perfectly in focus.
Now if we want to be a little more creative and want the bowl to be in focus (remember this is further away at the back of the shot) then as it is at the back of the other two items there is no way the camera could know that you wanted that as the main focus point. In most cases the camera would again focus on the flower and your results would not be as you wanted.
There are few ways around this... The first is to use manual focus (if available) and focus the lens on the bowl yourself.
The second is to frame the shot with the bowl in the centre of the picture, half depress the shutter to get focus lock and then recompose the shot to how you want it before completely pressing the shutter to take the shot. The problem with this method is that some cameras will also set the exposure of the framing at the time that you half press the shutter and it can (often) result in either a dark or a blown out picture once you have re-composed the shot.
The third may only be available on some more advanced cameras. Some cameras will allow you to select the focus point and by selecting the one closest to your subject when viewing the shot through the viewfinder. The camera will then use this and get the right spot to focus on hopefully returning you the correct results.
I did all that but my camera does not get focus lock?
This is the second problem, and to understand why you’ll need to know the basics of how camera auto focus systems work. To keep it very simple the camera uses the contrast of light between light and dark areas of the subject to get the focus lock. If there is little light or more importantly very low contrast in the subject, then its likely that the camera will not get an accurate focus lock. In more severe cases it will ‘hunt’ back and forth not getting any lock at all. More advanced (and expensive) cameras are more sensitive and able to auto focus in less light but even they will begin to suffer once the contrast goes and light begins to fade.
There are many ways to work around this problem, using manual focus is perhaps the easiest as the human eye is much more sensitive than any camera’s AF system. Increasing the contrast in the shot by adding lighting, thus allowing the AF system to work properly is probably the second most common fix. This can be by using flash (but this will also introduce shadows) or some cameras have an AF assist light that fires as you focus and will light the area until the camera gets focus lock. After this you can either deactivate the flash manually (on some cameras) and/or switch to manual focus to keep the focus locked and take the shot.
One other method (that involves no added gadgets and is usually possible with every camera) involves focusing on another subject that has more contrast or is better lit as your intended subject. You would do this then recompose the shot on your main subject and take the picture. If you use this method it is very important that both subjects are exactly the same distance (on the same focal plane) as each other otherwise the focus will be wrong.
So now you know how the AF systems work and about lighting, what else can go wrong?
How about camera shake?
You can have perfect focus but if you move the camera when you take the shot there is a good change that the end result will be blurred. Photographers have for years battled with this issue especially when shooting in difficult or challenging circumstances. The factors that effect this are the movement of the camera and the amount of time that the shutter is open to capture the image (shutter speed).
There are two solutions at hand for this little issue...
The first one is to attempt to use a shutter speed that is fast enough to prevent camera shake. The problem with this is that everyone is different and some people are much steadier than others, enabling them to use slower shutter speeds and still get good results, while others less fortunate will need much faster speeds for the same circumstances. Also to make the situation slightly more complicated camera shake is also affected by the shutter speed in relation to the focal length (or amount of zoom you are using) just working with one factor and ignoring the other will lead to poor results.
So how do I work it out then?
Here is a simple rule of thumb...this means that in the majority of cases it will work and it is meant as a guide only, if you are one of the steady people you can probably go slower, if you one of the less fortunate ones, you’ll need faster shutter speeds.
The rule states "The minimum shutter speed should equal your focal length".
60mm handheld you shoot using a shutter speed of 1/60th sec minimum.
100mm handheld you shoot using a shutter speed of 1/100th sec minimum.
200mm handheld you shoot using a shutter speed of 1/200th sec minimum.
400mm handheld you shoot using shutter speed of 1/400th sec minimum.
This is really simple to remember as both numbers always match up.
As usual it is not all as simple as it first appears though, first if you are using a basic camera you may not have control over manually setting the shutter speed. In circumstances like that most cameras have "sports shooting" mode (symbol of a person running on the mode dial). This will give you a faster shutter speed generally, but the camera will still be in control. For the more advanced using DSLR’s there is a good chance that crop factors will become involved. These basically alter the effective focal lengths and should be considered in the above calculations. We already have a chart showing the Effective focal lengths of digital cameras, this can be referred to for reference.
The second alternative is to use remove the human element.
You can shoot at much slower shutter speeds without getting any camera shake if you use a solid object to support the camera. The obvious one is a tripod but many people will also use monopods (just like a tripod but with only one leg) or if you don’t like carrying the extra weight, you can use any solid objects that are available at the location. In the past I have used everything from rocks, gateposts, and fences through to seats, park benches, car roofs etc. anything that is solid will do. You will get much more flexibility using a tripod but in a tight spot use whatever you have available. Also some third party manufacturers now make and sell bean bags. The 'bean bag' will form a shape that is much easier to work with and besides supporting your camera better will also offer an extra degree of protection too. These can be used in exactly the same circumstances as previously described to give a good mounting (on a wall, post, fence, rock etc).
In addition to removing the need for the human element using the self timer (if your camera has one) for static and unchanging scenes also reduces the chance of moving the camera when the shutter is released, as you don't have to be touching the camera after initiating the self timer.
Also If you can't find something at the right height to put the camera on, you can often find something you can brace yourself against, (tree, wall, car) and by holding the camera as steady as you can (wedge your elbow, arms against your chest without using too firm a grip), breathe in and hold your breath when you release the shutter. Using this method can often return great results while shooting at much slower shutter speeds than you would normally attempt.
Ok so I understand light/contrast requirements, I have focus, I have eliminated all chance of camera shake but my shots are still blurred?
The last possible issue could be the subject itself. Just as you get blurring from the camera moving, you can also get blurring from your subject moving too.
Shooting flowers being blown in the wind at 1/60th sec will not return sharp results, neither will trying to photograph a Formula 1 car going past at 200 mph. You will need to adjust your shutter speeds (and in some cases shooting technique) to enable you to get sharp results for different subjects. There is also the issue of your full size pictures being sharp but when you reduce their size for display on the web or to email to friends, you lose detail.
Unfortunately these are both subjects that deserves separate article in their own right.
You can check back in the future and I may just have put something together.
With grateful thanks to the following Pixalo members - Dabhand 16, Markulous and Sonsey who all contributed content.