When your subject has a strong light source behind it, the subject is going to appear darker compared to other parts of the scene. Although this is normal in such shooting situations, it is possible to achieve the desired exposure by using the following methods:
- Use a flash.
- Adjust the exposure compensation.
- Use a reflector panel.
- Use a flash extender.
Since you are shooting towards a bright light that is causing your subject to be shadowed, you can try using a flash to compensate. Whether it is a built-in camera flash or external flash doesn't matter, as long as it helps illuminate your subject.
Another option is to adjust the exposure compensation. Depending on what you want to achieve, the exposure compensation can be either increased or decreased. Keep in mind that doing this affects the entire image. It is possible certain objects in the photo may become overexposed when increasing the compensation. Decreasing the compensation causes your subject to silhouette, but also can cause other objects in the background to silhouette as well.
If possible, consider using a reflector panel near your subject. A reflector panel simply bounces some of the light back towards the front of your subject, helping to brighten up the darkened shadow areas caused by the strong light from behind.
In some situations you may find a flash extender to be useful. A flash extender connects to your external flash and magnifies the flash power. It is beneficial for shooting far away subjects.