We're conditioned to think that a blurry photo is a bad photo, but that isn't always the case
It wasn't that long ago that we published a article here on Photocritic running through five points to help you achieve sharply focused images. We talk about the perils of vibration and camera-shake elsewhere, and plenty of our tutorials recommend making use of a tripod. We even have a how-to showing you the steps to fashion an emergency tripod from a piece of string if you're desperate. So you'd think that blur is the constant enemy and your photos always need to be pin-sharp.
That's true most of the time, but not always.
On occasion, a little softness it desired. Blur can inject a sense of motion and movement into your photos. It can be suggestive of mystery in an abstract photo. Effectively deployed, blur can reduce the prevalence of distracting elements in your frame, thereby drawing attention to your point of focus. And with some techniques, for example pinhole photography, blur is evocative of the medium.
Properly handled, blur is a meaningful tool; it isn't necessarily suggestive of poor camera handling.
Using long exposures will allow you to capture a sense of motion and movement within your frame, bringing a sense of dynamism to your photos.
The classic examples of motion blur in long exposure shots are the rear lights of cars, trailing off into the distance or a flowing stream of milky-smooth water.
You can use blur to ensure that the viewer's eye is directed precisely to the subject, rather than being distracted by an intrusive background. At its simplest, you can accomplish this sort of effect by using a very large aperture and focusing on your subject carefully.
You can, however, take this further by using a selective focus lens, for example a Lensbaby.
Or you could use the long exposure technique to isolate a static subject and emphasise the busyness around her, him, or it by capturing that in a state of motion blur.
Blur by design
Using a pinhole lens will almost certainly produce a blurred image, unless your subject is able to hold perfectly still, because a longer exposure is the only way to introduce sufficient light to the film or sensor to create an exposure.
In many respects, these images are beautifully impressionistic, and the lack of detail is what makes them so appealing.
And of course, the lengthy exposures and subsequent blur of pinhole photos can be what makes the photo itself. For a wonderful example of blur being a part of the photographic process, take a look at Katie Cooke's wonderful series Balancing Act.
Or a blurred look to an image, whether shot with a pinhole camera or not, is part of the story of the photograph.
But still in need of tripod
The chances are, if you intend to create evocative and appealing blur-filled images that look deliberately created, rather than accidental, you will need to use a tripod. Camera-shake and motion blur are different beasts. Remember, blur can be a story-telling technique, camera shake requires better camera-handling.