Sometimes cameras struggle to cope with the range of brightness in an image - the human eye is far superior in this respect. So, on a sunny day you can appreciate the beautiful sky while still being able to see things in shadow. Photographs often turn out disappointing under these circumstances - the pictures aren't as colourful as you remember the scene being.
This is less of a problem for old-fashioned cameras than digital ones. Colour negative film has more "latitude" than digital sensors, especially for slower film speeds. As digital cameras took over, it became increasingly difficult to buy 100ASA (slow) film, as most shops stocked only faster film, 400 ASA or 800 ASA. This is more suitable for cheap cameras with fixed focus and a small aperture to permit a half-decent depth of field.
Anyway, I've been experimenting with different methods of adjusting the exposure of photographs to get improved results.
The pictures above were taken at Loch Lomond in October 2008 on a gloriously sunny Autumn day. The first one was taken with the exposure set to automatic. It illustrates one of the problems I have - the clouds lack detail. It is possible to darken the sky in the computer, but it is likely to end up an unnatural greeny-blue colour (as in the second picture). Basically, the light is so bright that the camera sensor has become saturated. Very bright shades end up as the same colour, and no amount of computer processing can restore lost information.
Many cameras feature some way of adjusting the exposure at the time of taking the picture. One method is to automatically reduce the exposure for all pictures, which would improve the sky, but might make the ground too dark. I've done this in the past, using Photoshop to adjust the ground later and make it less dark. Unfortunately, I reckon this gives poorer results than sticking with the standard exposure and darkening the sky. I often try it both ways and pick the one which comes out better, unless the lab automatically readjusts the exposure and they come out almost identical.
On this occasion, I tried a different approach. The bracketing function on my camera allows you to take extra pictures with different exposures. With this feature enabled, you take three pictures of everything. I had it set up so that the first picture was exposed normally, the second was overexposed by 1 stop (twice the exposure time), and the third underexposed by one stop (half the time), hence the three photographs above. The sky came out beautifully in the underexposed shot, while the trees and foreground were better in the other two. I cut the foreground from the second picture, so that I could be sure of getting all the shadow detail, and pasted it on top of the third photograph. I adjusted the two halves separately. Some work was needed on the tops of some of the trees, as I used a soft edge at the join, and this gave a slight double image in places where the two parts of the picture didn't quite match up. Using a tripod would help, but I'm getting good at holding the camera steady enough for this trick.
The picture below shows the final photograph.
What do you think? I reckon it looks quite good on its own, and the bright colours have a lot of impact. On the other hand, next to the first picture above it looks a bit freaky. The next step would be to try printing it, but getting the printing to work out is a whole new problem...