Digital Diversity

One problem you can encounter in photography is lack of dynamic range. The dynamic range is the range of light levels that can be seen from black to white. You will often find that while a photo has well exposed shadows and mid-tones, the light parts of the image are far to light or even blown out (pure white). On the other hand you may have exposed for the highlights in which case the shadows will look overly dark and underexposed. The problem this leaves is that what you see with your eye is certainly not what you get using your camera. The solution here is to take multiple exposures and blend them together to increase the dynamic range of the shot. You can use as many shots as you like but for the purposes of this tutorial it will be done using 3 shots.

There are 2 ways to get the multiple exposures. The first is exposure bracketing. This is when you set your camera up to take multiple shots of the same scene at different exposures. How you would do this depends on your camera. Many DSLRs and also advanced point and shoots have an option for this to be done automatically. You just hold the button down and the camera will take 3 shots, each time adjusting the exposure. You can normally set how much to do this by. If you set it to +/- 1 then it will take 3 shots, one at the original exposure, one a 1 stop above this and one at 1 stop below.

If your camera does not have this option then you will need to use a manual or semi manual mode to do this. For example you can use aperture priority, take the shot then use the exposure compensation to create the other 2 shots needed.
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Its every photographers nightmare. That fuzzy grain and colour dotting that seems you ruin your images. Noise. It lives in the shadows, loves high ISO’s, grows as you correct underexposed images and it destroys detail throughout a shot. So how do you beat it?

Photoshop has the tools necessary to help you here but its a good idea to remember how to minimize noise in the first place:

• Firstly, and most obviously, try and use the lowest ISO value you can get away with. As you increase your ISO noise will rapidly start increasing in your shots. Don’t let this rule hold you back to much because some cameras handle noise a lot better than others. For example, with my Canon 500d, I will comfortably use ISO 1600 when needed and even push to 3200 if I have to. However if I was using my cheap little Ixus I wouldn’t want to be going any higher than ISO 200.

• If indoors a flash can help keep noise values down. But why? well point three answers this.

• Get exposure correct at the time of shooting. I really cant stress this enough. Try it now. Set your camera to a high ISO value and take 2 shots. One with correct exposure and one that’s underexposed by a stop. Now correct the underexposed shot and noise will flood in.

• A way to further reduce noise is to over expose a shot and then correct it in post. This is a proven technique but does have its drawbacks. You will end up with slower shutter speeds and run the risk of blowing any highlights in the shot.

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Learning how to expose photos in anything but automating modes can start to get confusing. When I got my first digital camera (Ixus 75) I didn’t know much about cameras in general, let alone metering modes and correct exposure.

When I upgraded to a superzoom (panasonic fz28) I switched to aperture priority mode. My main reason for this was that I could choose the aperture and change the ISO and exposure compensation to alter my shutter speed. This served me well and a lot of people use this method. I pretty much stayed clear of manual mode as it just sounded to fiddly to be of any use.

Since I got my DSLR (Canon 500D) I have started to think about this more. The only problem I would get with aperture priority was inconsistent exposure. What I mean by this is that say I was photographing my dog. As he runs passed different colour backgrounds this will in turn effect the exposure settings and lead to an over / underexposed shot. This would in turn have effected the shutter speed and can cause unwanted blur. I would also have to use exposure compensation and sometimes I may forget to change it back which would ruin the next shot. Another problem I had was that the exposure lock button never seems to lock the exposure for very long and getting the exposure back to what is was can be a pain.

To escape these problems I needed to step into the realm of manual mode.

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