In the olden days, and for those of us who still use film, image graininess was something we tried our best to reduce. If it was impossible, then you tried to integrate the grain into the picture so it added a certain feel to the final composition. Sometimes, the grain was even a planned part of the composition, much like modern film makers use the “8mm” look when they want to achieve that certain edgy and grainy feel to their films. In the digital age we still have this “problem” but it is generally refered to as noise.
Just like with film, the amount of grain/noise is dependent upon the ISO of the camera. In analog (aka film cameras) this was/is determined by the actual film’s ISO, and in digital it is determined by an ISO setting which varies the sensitivity of the sensor. Since most of you are going to be using a digital SLR or point and shoot (P&S) cameras, I am going to focus mainly on the digital realm. Let’s start with the basics of ISO and photography. In a nutshell, the higher the ISO speed the more sensitive to light the sensor becomes. What this does is allows the photographer to shoot at faster shutter speeds in low light, which is excellent for night shots or indoor shots where light is scarce. However, this ability comes at a cost and that cost is more noise/grain in the final image.
Below is an example shot. 
The image was taken with a Nikon D80 through the kit 18-135mm f/3.5-5.6 lens. The left half is set at ISO 200, the right is roughly the equivalent of ISO 1600. I will admit, in this instance, I have faked it in Photoshop, hope you’re OK with that since it’s easier and still gets my point across. As you can see the left is very clear even though the light is very low inside the church. On the other side, there is a very clear grain to the image. As you can see this detracts from the image quite a bit. The sharper half was about a 1/30th second exposure and I hand held it. Obviously, 1/30th second is pushing the lowest speed one can use to get sharp images with hand-held shots, however had I upped the ISO I could have shot at about 1/160th second, which is very acceptable for handheld shots. The downside of this is the horribly grainy image you see on the right side.
You may be asking yourself what you can do about ISO to ensure you get the best quality images every-time you press the shutter release. Well, since higher ISO is bad, you simply need to make sure you keep the ISO is as low as possible. This means moving your camera from the very Safe “Auto” mode. I know, I know, you’re hands are shaking thinking about it, but trust me when I say that with a little practice you can take much better images when you abandon the Auto. most ever other mode on modern cameras will give you access to ISO control. (ie. Aperture Priority, Shutter Priority, or Manual (Av, Tv, and M on the selection dial))
With the sheer number of cameras that are out there I can’t go through all of them explaining how to use yourself, so I suggest a read through your manual. You know … that little book that you tossed in a drawer without looking in it? For those without a manual, you could probably find a PDF of the manual online at your camera’s manufacturer’s website. But, for you DIYer people, here is a basic run down. On a P&S camera there should be an ISO setting under the Menu option. On the DSLRs there is often a “min. ISO” option, you should set this to the lowest available option (usually 50, 100, or 200). This lower ISO will ensure you get as sharp an image as possible, but this usually means a longer exposure time. This of course goes back to Rule #1 about tripods. If you follow that rule, this one will be cake.
OK then, tinker around with your cameras, get those ISOs down and start getting better shots. See ya next post!
Tags: camera, grain, ISO, noise, photography
