For the latest two iPhones, you can choose where the camera focuses on by tapping the screen prior to snapping the picture. If your dealing with dark/light areas, taping will change how the camera sees the whole area. Tapping dark will cause the brighter areas to wash out, tap the lighter area and the dark areas go black.
An app I use all the time when I want to take a picture that had light and dark areas is Pro HDR. I have written about it before. Using the app, you tap the bright area which the camera adjusts for, takes a picture. Then you tap the dark area, the camera adjusts, takes another pic, then marries the two together. It takes a bit longer and an extra couple finger taps but you get images that are just like what you would see with your eyes.
Pro HDR was just updated with an ‘auto’ option. Now, you tap once, the camera adjusts all through the range, goes back and snaps two images on it’s own, merges the two together and gives you a finished image.
iOS4 has given us a much faster camera action, which I enjoy when just snapping pics. When I have a bit more time and there are not moving objects, I use Pro HDR. It does require you stand still for about 10 seconds, but the output is well worth is.
Here is an example of the two images joining. Normally you would choose either outside or inside to be clear (viewable brightness, not focus). Pro HDR also aligns the two images since you most likely move a little between the shots being taken.
After merging and aligning, you are given a chance to adjust the overall new image to tune to what your looking for.
The final image is full size that the iPhone is able to do, no quality and size loss.
The above window shot was just to show something dramatic so you can see what is possible. More along the lines of what I use the app for every day is product and landscape shots. Below, normally you would have the wood or the MiFi bright and the other dark or washed out. With this image, I did crop to fit my need using Photogene. An app that is fast for rotating, scaling and cropping.
Finally, a quick image from downtown. Again, just taking the picture without going through Pro HDR, you would have black trees that look like fuzzy areas or the building would be too bright to appreciate it.