I've recently released a new freeware exposure and focus blending program
called TuFuse.

TuFuse is based on the same image fusion algorithm as Enfuse, but works a
little differently. It performs a "two stage" fusion process that is designed
to perform focus blending and exposure blending in two stages. Enfuse uses a
single stage fusion algorithm that works well for either focus blending or
exposure blending, but isn't optimally suited to addressing both
simultaneously. For example, If one input image contains a well exposed, but
poorly focused, pixel, it will still contribute to the final composite, even if
a well exposed and well focused pixel is available in another input image.

Tufuse performs focus blending and exposure blending in two different stages to
create a better result. It is able to determine which images ought to be focus
blended and which ought to be exposure blended without user input.

TuFuse has a few other differences, and includes an "auto-bracketing" feature
to create fused images from a single input image, similar to "pseudo HDR"
images created from a single exposure.

TuFuse is a stand-alone Windows command line program, and is released as
freeware:

http://www.tawbaware.com/tufuse.htm

TuFuse is also distributed with PTAssembler 4.0 (and later) as its default
image stacking plugin program. (PTAssembler 4.0 also supports Enfuse and
CombineZM as stacking plugins). PTAssembler acts as a GUI for TuFuse (and any
other stacking plugins), to align (register) images before stacking.

More information about TuFuse/PTAssembler:

1. http://www.tawbaware.com/forum2/viewtopic.php?t=4797
2. http://www.tawbaware.com/ptasmblr_help_stack_example.htm

Max