Imperfection in Images - I Soft is bad

Saturday, January 06, 2007

Often I get to talk to people who are just beginning to learn and try their hands on photography. They do some ground work, try to understand about the skills and techniques, get an idea of what makes a good composition but still come back home wondering why they are not able to make arresting images. I can often spot some basic flaws in the images. Thats when I realized that it is easy to read about what to shoot and how to make great images, but few people get to read about what makes a bad image and what should not be done. Here is an attempt to fill that gap. This is a multipart series on imperfections that can appear in an image.

SOFT IMAGES ARE BAD IMAGES

There are several occasions when you could have taken a picture and loved it's composition. When you see in a smaller size no bigger than the screen of 1024x768, it might look fine. For the trained eye, even 640x480 image is sufficient to evaluate the sharpness, but a beginner might mis-judge it. But if the full-blown image shows any signs of camera shake, or that you find your subject out of focus or if the depth of field is insufficient, the only place that the image deserves to go to is the trash can.

It may look fine to post on the web at a smaller resolution, or to print a post card size image, but soft images do not do good for professional use, or to make big prints. And as you start processing a soft digital image, you will see that it deteriorates faster than a sharp image. A soft image also means there is no way to make good prints. Besides, if you take two shots of the same subject, with one slightly soft(introduced by camera shake or because the subject is slightly out of foucs) and one perfectly sharp image, you will always notice that the sharp ones looks distinctly better than the soft one. This is true even in smaller sizes when the softness of the image may not be obvious.

Look at the example below. These images were made on different days and composition is slightly different, but it should do good to show the difference. The first image was taken on a day when there was a dramatic colorful sunset, but I did not have a tripod. The image came out soft but it is not obvious in the small version here.



Next, look at the image below. I did not have a colorful sky when I took this, but I had placed the camera on a sturdy professional tripod. You can see that the clarity and appeal of this image exceeds the first image, even when this image is made when the sky is not so colorful.



To demonstrate further, I have taken a small section of full-sized image to show how much difference can sharpness make. The latter image is in fact also better exposed, but even when you compare sharpness alone, you will know that a sharp image makes significant contribution to the overall quality of the image.



HOW TO MAKE SHARP IMAGES?

Unfortunately, there is no better way to make a sharp image than carrying around a bulky and sturdy professional tripod and shoot with the camera mounted on it. But there are ways to improve.

1. Learn the correct way to handhold the camera. I keep my left hand below the lens and support it. My right hand holds the camera, with an adequate grip(not too tight, not too loose) making a comfortable support. When I am taking a picture, I breath in, hold my breath while I click.
2. Click gently. This is the time when you induce maximum vibration in the camera. Do not make a fast/rapid movement of fingers which can shake the camera. With camera in single-frame mode, click gently, hold it depressed for a short time and then release. Do not release instantly. Essentially practice to click with little movement of hand except for the forefinger which depresses the shutter button.
3. It is generally recommended that you do not shoot at shutter speeds below inverse of focal length. That is, if your lens is 200mm, stay at shutter speeds faster than 1/200sec. Though practically you can manage to shoot at slower shutter speeds, this is a safe bet.
4. Use lenses with image stabilization where possible. IS lenses are no match to using a tripod, but very useful when shooting handheld. But remember to turn off IS when the camera or the lens is mounted on a tripod.
5. Always keep a watch on the shutter speed. If it is going too low, it is preferable to shoot at a higher ISO than get a blurred image.
6. The best way to get sharp images is to make it a habit to shoot with tripod. And to make best use of the sharpness that you can get from a tripod, use a cable release or remote release. Using the Mirror Lock-Up also helps. And it is important to ensure that you buy only good professional quality tripod and a matching head. Inexpensive tripods do not really do much in keeping the camera sturdy.
7. More expensive, professional lenses make images that are a great deal sharper than cheap kit lenses. Buy them if you can afford them!

You can also use software tools for sharpening an image, such as Photoshop Unsharp Mask. They can help sharpen the images to some extent, but are of little use if you have started with a bad image. Such tools can be useful when you do not have expensive lenses that can make sharp images. Keep in mind that software tools are no replacement to making a sharp photograph when you are taking it.