Sunday, July 1, 2012

Shooting In Low Light Condition

After being bombarded by people recently on how to shoot in low light, I figured this would be a good topic to do a post on. Most of the question centred around shooting people in low light and the problems of getting a blur when the photograph was taken. Those who were a bit more advanced, talked about grainy images with high ISO. Let's tackle both of these.

Blur Caused by Camera Shake
Getting rid of the blur. There are two kinds of blur which a photographer will face when the take photos in low light, blur caused by camera shake and motion blur. Camera shake happens when your hand moves while the shutter is still open, there by creating a blur in the image. Image on the left.


You can compensate for this if your camera/lens has image stabilization. It is basically a mechanism where the lens elements or the sensor move counter to your hand movements, countering the camera shake and keeping the subject in one place. This is known by many terms, Image Stabilization, Vibration reduction, optical stabilizations, vibration compensation, stead shot etc. You get the point. Usually if this exists then you should get about 3 stops of light so you are shooting at 1/50th, you can shoot hand held 1/6. (Though I would not be so keen on doing that. My hands are not so steady hence even with this technology enabled I do not go so low.)  In more technical terms you can shoot with a really slow shutter speed


Now, if you don't have this technology then take a deep breath, hold the camera stead and then take the image. That should work. If you are one of those people who plan ahead then, you can bring a tripod or a mono-pod along with you for such situations. When you shoot at a really slow shutter speed it will create the second problem, motion blur. More on that a bit later. Another way to avoid camera shake is to increase shutter speed and to get a proper exposure increase the ISO( which will create the grain problem which we will look into after motion blur)

The Motion blur problem- This occurs when the shutter is left long enough that the subject moves before the shutter closes and it creates a blur. Here is an example. 
Motion Blur. The Car has moved before the shutter closes
This would typically happen if you shoot auto or semi auto - aperture priority. In this case the camera will determine the shutter speed for a correct exposure.  (though it can happen in full manual as well in which case the person behind the camera made an error in calculation) Invariably you will get motion blur if the shutter speed falls below 1/50th of a second. Getting rid of this blur is easy, increase the shutter speed. Shooting close to 1/125 should be fast enough to capture most movements. You can go slower to 1/50th of a second but that depends on the situation. In that case you would need a tripod/stead hands or image stabilization.

Moving up the ISO. - ISO is the sensitivity of your sensor/film to light. Higher the ISO more sensitive the sensor/film to light. In an ideal world we could all just move the ISO up and be happy. We would be able to  shoot with a faster shutter speeds and capture the moment without any problem. Sadly in the real world, we get ISO noise or colour noise. The higher the ISO the more the noise. There are a few ways you can compensate for this. If you light your subject well even at high ISO you will not notice much noise.


Adding light. You could use you camera flash to illuminate the subject. However on camera flash creates very flat and not so pleasing images. If you are mounting a flash then you can bounce the light and make the light source a bit bigger and make the image more pleasing.
Another way to add light is to get closer to the light source. It may be a street lamp or light on the wall or maybe light coming in from a window. More light equals less noise, lower ISO and a higher shutter speed.


Some other techniques


Post Processing: You can use techniques in photoshop/gimp, Noise Ninja, Lightroom or few other software's to get rid of the the noise. Except for Gimp which is free the others are paid. 


Converting to Black and White. Most of the noise and grain looks ugly because the colours start to distort. If you convert the image to black and white /sepia the grain will make the image look more artistic. You can actually use this to your advantage and use it as an effect.


Shoot raw. If you shoot raw you have more options in post processing. Raw images store more light information and you can salvage an under exposed image in post processing. Also if you have this information, in the future when technology gets better you may be able to get rid of the noise better as compared to a jpeg .


Fast glass. This is another option you could use. Use a lens where the aperture opens up wide really wide f2.8 or f1.4. Now most of these are expensive but there is always plastic fantastic or the fast fifty. These retail for about Rs 5000 or Rs 6000. All manufactures make one and these are usually f1.8. One thing you need to keep in mind when you open the aperture so wide is you lose Depth of field (DOF). If get close to the subject then the DOF will be smaller, if you get further away then you will have more DOF. 


Shallow DOF. The Wide open Aperture
causes the doll in the background to blur out

The same image as above shot from a different angle.
Distance between the car and the doll is very small




In low light you could use the extended exposure technique I had talked about earlier.


If all else fails. Leave your camera and just enjoy the moment.


Some additional resources

Low Light Photography Tips


How To Get Better Digital Photos In Low Light Conditions Without Using A Flash


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