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Select the correct ISO speed before shooting

Elvis Elvis

The word photography can be taken to mean drawing with light (this is the word’s origin). Light is the most important component determining your results. (That is the whole reason why taking pictures at dusk or dawn is recommended by so many pros. More about that on the Landscape Photography page.)

Most modern digital SLRs have light sensitivity settings of between 100 and 1600. The higher the number, the less light is needed for you to still have a fairly fast shutter speed. Fast shutter speed’s is of course important for handholding and action photography. It ensures sharp pictures, and a sharp picture is what you want in 99% of cases.

However, the higher the ISO speed selected, the higher the incidence of digital noise, which is a form of image deterioration. Big words for such a small guy Select the correct ISO speed before shooting An image with too much digital noise looks like an image taken with a very grainy film. (I must say that with the introduction of the Canon EOS 20D this has become less of a problem than with the older 10D and 300D.)

I therefore always select my lowest ISO speed possible given the light available. On most SLRs this is 100. At this speed you will get minimal noise. If you are taking pictures at first or last light, in a forest, or on a dark and cloudy day, remember to set your ISO speed higher to allow you to still get sharp images. The extra noise is the price you pay for taking pictures in low light situations.

Select the correct ISO speed before shooting

However, there is an exception to this rule of the lowest light sensitivity setting possible. Digital photography has its advantages. One of these are that at an ISO speed setting of 200 there is little or no difference to an ISO speed setting of 100 (unless you are a real perfectionist, you won’t notice this or it won’t bother you). Shots taken at an ISO setting of 200 are surely fit for publication and in fact I often see shots with way more noise than that being published.

How low can you go? This has been answered above – very low. As I said, it is advisable to keep your ISO speed at one of its lowest settings if the available light allows this. How high can you go? I try to stay at 400 or below, but I have selected 800 in the past for special opportunities in very low light. However, the sacrifice made to image quality does get bothersome at this level.

Having to select a very high ISO speed should still not prevent you from taking pictures if there are special opportunities. If you find a pack of African Wild Dogs quite a bit after dark, set your ISO to its highest level and take a few shots. You never know what the results will be, and it might just be very pleasing. I know of professionals who used to push their film up to 3200 ISO when they felt the need to.

To conclude, you should realise know that the only way you can decide which ISO speed to use is to experiment with it and look at you results. On the newer camera bodies this is not such a serious consideration as it used to be on the first digital SLR camera bodies. Go out! Go play with your settings, and as soon as you have formulated an opinion on this, you will be able to implement it on a regular basis.

When you are in the field, implement ‘ISACA’ or this opinion you have formulated on ISO speed before starting to take pictures. It will improve your results!