Many of the features on a digital camera are there for marketing purposes. You won’t use them. Chips are usually about 100 ISO film speed, which is the same as old-fashioned medium speed film. In bright sunshine the exposure is 1/125 sec at f11. If you shot this subject at that on an old film camera with Ilford FP4 black and white film you would get perfect results. It’s the same on a digital camera. The only other thing you need to do is set the focus.

The table above shows a list of shutter speeds and f-stops that will be familiar to anyone who has used an old film camera. If you switch a digital camera to "M" for manual exposure you will see the same numbers, but with in-between numbers too, just to confuse you.

In the shutter speed column it is pretty obvious that 1/30th second lets in twice as much light as 1/60th. It is the same in the aperture column too - f11 lets in twice as much light as f16. These twice as much, or half as much light intervals are called a "stop". The term goes back to the days before the iris diaphragm, when strips of brass with different sized holes in them were inserted in the side of the lens to stop the light.

Film speed, also known as ISO, is the other variable we need to take into account. To get the best quality set your digital camera to it's lowest ISO setting (smallest number). Depending on the model this might be 64 ISO, 100 ISO or 200 ISO. 200 ISO is one stop (2x) faster than 100 ISO. If you were working at 200 ISO, the exposure for bright sunlight would be 1/250th at f11.

On 100 ISO these setting would give you good results:

Bright sunshine - 1/125th f11

Cloudy bright - 1/60 f8

Cloudy dark ( black clouds in summer, or an average December day) - 1/30 f4.

It is important to realise that your camera, despite all it's sophisticated electronics, is only making an educated guess, the same as you are!

There is more than one way to achieve the correct exposure, as you can see above. All of these settings would give the same exposure. 1/15th at f16 would render both the foreground and the background sharp, but you would need to hold the camera very still. This would be OK with a wide angle lens. To make the most of all this depth of field, focus one third of the way through the subject. If you were using a telephoto lens, which is more prone to camera shake, you would be better off forgetting about depth of field, and using 1/250th at f4.

Alan Tucker