Geesaman uses a technique that I believe was invented, or at least made popular, by photographer Michael Orton. The technique involves sandwiching two slides of the same scene which are overexposed, with one out of focus. When combined, the photo exhibits an interesting mixture of high and low detail areas, and a "dreamy" quality that is somewhat different than soft focus. To see some of Geesaman's work, click here.
Of course, not being a film photographer, I have researched how to reproduce the effect using digital photos and software. I have found two recipes online that I like, plus one that I came up with on my own. Of the three, none works the same on every photo. I usually end up making a version with each recipe, and then choose which one I like best. The photo below from a cemetery in Charleston, SC was done with my recipe, although mine doesn't always win.
Cross and Azaleas, Charleston, SC - 2013
(Click on photo to enlarge.)