Picture of the week 12.05

Birds flapping over the small canal.

Set the shutter speed low enough for the flapping to be not frozen, 1/6s in this case.

Blown highlights

Have you ever been annoyed with this in one of your pictures?

Blown highlights in the cloudy sky.

This is a common problem in digital photography where either the selected exposure or the camera sensor itself will push whole regions of the picture into complete white. This is why it is called blown highlights, as the highlights, i.e. the light parts of the picture, become totally white, hence "blown".

The question is, why does this happen and how can you prevent it?

This can happen because of two main reasons:

Over-exposure

If the picture is overexposed, you will see this effect. That means, if you let the sensor have much more light for a scene than is necessary, than it will interpret a light blue as completely white. This is because the sensor thinks the color is much brighter because of the over exposure. Generally, the rest of the scene will also look very washed out. Correcting this is quite easy, just correct your exposure compensation down a little bit. This will make the whole picture a bit darker and hence get the lighter colors to show instead of pure white. Here is an over exposed shot and a corrected one:

Lack of dynamic range

Dynamic range is used to describe the range of darkness and brightness that a sensor can detect.It is usually referred to in "stops". Think of it as a doubling of light intensity with each stop. The problem goes something like this. If a sensor with 7 stops of dynamic range is looking at a scene with 9 or 10 stops of range, the following happens. It cannot recognize all of the different steps and will in-effect truncate.
Make a picture of steps of range in powerpoint, and another range for the sensor.
If the sensor has a smaller dynamic range, it cannot distinguish the very light colors from the very very light colors, and thinks that it is all solid white. You then end up with the ugly complete white sky like the picture above. This is called blown highlights and occurs with small sensors. Larger sensors are much more likely to preserve the highlights, ending up with much nicer skies, as a result of their greater dynamic range.

Picture of the week 12.04

Defiant piece of grass in the middle of the road

Find a nice lump of grass with a clear stretch of road ahead. Lie on your tummy. Make sure the road is really empty, for personal safety! Compose the frame tight enough to avoid getting anything else in the frame that might compete for attention.

Picture of the week 12.03

Colorful spinning carnival ride. Altstadt, Dusseldorf.

The colors made this an obvious choice. Then it was simply a matter of finding the right shutter speed to get the desired amount of motion blur.

Picture of the week 12.02

Birds on a frozen lake.

Taken with a Sony H-1 at maximum zoom, pretty good quality from such a small sensor.