This week I thought I’d write about another subject that I am frequently asked about, noise. First let’s take a look at noise as it pertains to photography. What is noise? Well, noise is the pixelation that happens in your images when you use too much ISO.
Many of the new cameras are capable of high ISO settings, some as high as 256,000 believe it or not. Increasing the ISO on your camera allows you to compensate for low light conditions but is not the ideal way to compensate for it. The ISO setting makes your cameras sensor more sensitive to lighting and your exposure. As you move the number higher, you camera is able to pull in more light from the available light in the conditions. The bad part is when you go too high in ISO, you start getting noise introduced into your images and they start to look sloppy instead of having a nice, fine quality.
Even though most modern cameras can go to large ISO settings, it’s not recommended to do so as the quality of your image will suffer. If you ask most any professional photographer, they will tell you that the maximum ISO that anyone should ever use is ISO 800, as once you get above ISO 800, noise really becomes an issue. Ideally, they will go on to tell you that ISO 50 or 100 is the best to use as it offers the finest quality to the final image. So, how do you keep down the noise if you are shooting in less than ideal lighting conditions? By using a better lens, capable of a wider aperture to allow more light to reach your sensor or by using artificial lighting, such as strobes or continuous, hot light kits. Look at this image I shot at ISO3200, notice all the noise?
The wide lens option is the best as a lens with a wider aperture will naturally allow more light in. Thins of the aperture of your lens as being the same as the pupil in your eye. When you are in low light conditions, your pupils enlarge so that your eyes can take in more light and allow you to see better. If it’s a bright, sunny day your pupils will become very small as you don’t need as much light allowed in to see. Aperture works the same way as your pupil, when you have a wide aperture lens, say an F/1.4 your lens is opened up allowing more ambient light into your sensor to make the exposure. The down side of wide aperture lenses is that they are generally expensive. Take the most popular lens from one of my earlier posts, the 70-200mm. As I mentioned in that earlier post the 70-200mm from Canon comes in two apertures, F/4 and F/2.8. The F/4, which I currently own is a fantastic lens and takes beautiful images with outdoor light, but if I needed to shoot indoors, say at a concert or indoor sports like basketball the F/2.8 will work better because it can open wider than the F/4 and let more of the natural light in that environment into my sensor. The difference in price is significant, with the 70-200mm F/4 L lens costing around $800 and the 70-200mm F/2.8 costing around $2,100. Now look at the same image shot at ISO100, notice how much better the quality is?
As I mentioned earlier in this post, the other option to prevent noise is to use artificial lighting such as a Speedlite external flash, or full blown strobes or even hot lights. These will allow you to keep your cameras ISO down really low if the lights are powerful enough to compensate for the poor natural lighting. Flash is not ideal in most low light conditions such as concerts or indoor sports as the flash is distracting, which is why if you are at a basketball game or watching one on TV you will notice that most all of the sports photographers there will have no flash but will instead be using that big fat F/2.8 70-200mm to get the shots they need for sports magazines and websites.
Now, since most of the AI family reading this post are students, I am assuming you are not rich enough to buy all your lenses at F/2.8 or wider as it is very costly. I would recommend to you that you invest in one expensive F/2.8 zoom such as the 70-200mm and buy the rest of your lenses in whatever aperture you can afford and use. If you do want to buy a good 70-200mm F/2.8, then you can always rent one from www.borrowlenses.com or from www.lumoid.com. I personally love Lumoid as they let you try before you buy and if you want to own that lens, they will split that cost up over three months to make it more affordable. I am not certain Borrow Lenses offers the same option as I have never used them but I know Reuben has and he can probably best answer that question.
Now get out there and make some great images.