Sorry, I posted this in the wrong forum before:
I hope some one can tell me what I’m doing wrong here. I want to create a background image for use with lightcaps. I have cropped an image so that is has a ratio of 2:1 and made it the same height as the document. I create a new background in the lights menu, then import the image. Each time I import it, the image is much bigger than the document, despite having the same height. No matter how small I make the image it is always much bigger than the document. Also, in the ZBrush documentation it says you should press the camera button in the transform menu to snap the image to the document, but my camera button is always greyed out. Can anyone help with this, please? 
When you create a background in the Light palette you are creating an all-round background. That’s why you only see a small part of it in the document window. For best results you need to use a panorama type image, such as the one that is included in the Texture palette (Texture 01). When the Rotate With Object switch is on, rotating around your object will rotate the view of the background. That typev of image is best if you want to use it for creating a LightCap. Because the image is all around the object the resulting lights in the LightCap will be all around the object too.
If all you want to do is have an image in the background then you could use the Image Plane plugin to load the image. If your model is in Edit mode then the image will be placed behind the model. If you want the image to fill the document window then make the document to same size or proportions as the image.