Ever wondered why your DSLR couldn’t take night shots as good as you wanted or how is that dreamy blur effect is taken, the answer is “long exposure”.
I am not going to brag about the theoretical definition, instead I am targeting readers who always wished for a simple explanation. Before jumping on the bandwagon of technical terms, let us understand how an image is developed by your camera.
How do Sensors work?
Digital cameras have a photosensitive chip, so it is sensitive to light. When you click the shutter button all the light that is being projected on the subject from a light source like sun or such is again reflected from the subject to the camera’s lens. Now lenses have something called Aperture which is nothing but just an opening or a hole which allows light to pass through, aperture is there because it lets you control what amount of light passes through the lens (that is where f-stop number comes in action, lower the number bigger the opening and more light gets through and vice versa).
After the subject’s reflected light is directed from aperture it hits the shutter and here your fingers come in the role. Until this point, the process of light reflection is constantly happening the moment you removed the lens cap. Now when you press the shutter button that light passes through and hits the sensor.
Sensors, as they are photo-sensitive records light based on the amount of heat bouncing on the chip itself. After that with some magic that analogue signal is converted into the digital image (with the help of image processor off-course) and is then saved to your memory card.
My camera suck at night shots!
If you ever felt like this after taking a shot then you are in for a treat. The long exposure will not only help you deal with this situation but will also provide creative ways to shoot amazing images. Most of the time its the limitation of the lens aperture that bounds the amount of light into your camera.
Long exposure allows you to let in more light even if your camera’s aperture doesn’t allow you to do so. You simply increase the duration of your shutter and give enough time for the sensor to capture adequate light. The picture ain’t clear yet, right?
Let me present you with an example, suppose normally you point your camera to the subject and press the shutter. What happens there is you digital processor identifies the scene and based on the lens capability opens up the shutter for say 0.5 sec but this limits the light that got in, assuming you are taking the image at night which generally results in dark image. Now with the long exposure you increase the duration of your shutter for say 1 sec adequate enough to get in proper light for the sensor to create the clear image but this comes with a price, shaky shots. Yup! you have seen it.
The science is that when the camera identifies that the light source is not enough the shutter is kept open for more than usual and as we don’t have steady hands the image gets distorted and blurry while the image was being recorded, the only solution here is to breath like a sniper or resort to a tripod.
So, how do you do it practically?
All DSLRs have Shutter-Priority, Canon reads as “Tv” and Nikon as “S” on their dial. Put your camera on that particular mode and experiment with different shutter speeds. No text can teach you better that experimenting.
How to blow one’s mind?
Now comes the exciting side and my favourite one as well. Taking creative shots with long exposure.
The key here is finding a stagnant subject with the environment in motion. Initially, you experiment with different shutter speeds until you find the exact number, which does not blur the main subject but in the same time blurs the surroundings. With time, you will know just my looking at the environment what shutter speed to choose for the shots.
There are varied subjects that can be benefited with long exposure.
Star trails and traffic.
Photo Credit: Matt Molloy
To get this shot you set-up your camera on a tripod and set the shutter for quite some time.
Shots of traffic won’t take more that 30 odd seconds but star trails are something that needs patience and knowledge, most of the time you’ll end up spending hours or so developing one image not to mention you need nature’s approval as well for a beautiful clear sky.
Smooth and foggy water.
Photo Credit: Wilf
Street photography depicting busy city life and rush, titled: The Other Side.
Photo Credit: Jianwei Yang
One of the best subjects for beginners to experiment with,
Photo Credit: Joits
There are tons of questions to explain and tons of shots to experiment, but I feel they better be a topic of another post.
If you have any queries about long exposure fell free to ask in comments.