Digital blending

Exposure bracketing with under and over exposure 1.5 stops apart. Lock the exposure and use a tripod if possible.

Open both under and over exposed files in PS and paste one as a background layer on the other. If you have file problems try working in 8bits instead of 16.

Painted Mask

Layer->Add layer mask->Hide all. With a large paintbrush paint over the light part of the image, removing the overexposed part revealing the darker part. Do the meeting line with a small brush.

The layer mask

After pasting the images, add a Layer Mask. Click on the background layer and select the whole image. Copy it to the clipboard. Now hold down the ALT key (Option on the Mac) and click on the white mask rectangle on the Layer 1 palette.

The whole image will now turn white. Next paste the contents of the clipboard onto the white mask. You will now see a B&W mask image. With the B&W mask displayed go to Filter / Blur / Gaussian Blur and set the Radius to about 40 pixels. Click on the Background Layer and you're done. You may want to select the background layer and add an appropriate curve to brighten up the dark area a bit prior to flattening the layers.

via: Luminous Landscape