|Lone Tree, Zion National Park, Utah|
Using a focal length of 150MM presents a few hurdles if one wants a sharp image from near to far. To counteract this one makes several exposures moving the focus so all parts of the image were in focus, albeit on different exposures. I then blend all of these images in a third party application, Helicon Focus. Helicon will create one focused image from however many partially focused images you capture.
Well worth looking into. Helicon will also control focus on many DSLR cameras particularly when doing macro photography. Check out the link above.